The following is a conversation with David Kipping,
an astronomer and astrophysicist at Columbia University,
director of the Cool Worlds Lab,
and he’s an amazing educator
about the most fascinating scientific phenomena
in our universe.
I highly recommend you check out his videos
on the Cool Worlds YouTube channel.
David quickly became one of my favorite human beings.
I hope to talk to him many more times in the future.
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And now dear friends, here’s David Kipping.
Your research at Columbia is in part focused
on what you call cool worlds
or worlds outside our solar system
where temperature is sufficiently cool
to allow for moons, rings, and life to form
and for us humans to observe it.
So can you tell me more about this idea,
this place of cool worlds?
Yeah, I mean, I think the cool world
is a place where we’re constantly
in contact with the universe.
So we’re constantly in contact with the universe.
So we’re constantly in contact with the universe.
Yeah, the history of discovering planets
outside our solar system was really dominated
by these hot planets.
And that’s just because of the fact
they’re easier to find.
When the very first methods came online,
these were primarily the Doppler spectroscopy method,
looking for wobbling stars,
and also the transit method.
And these two both have a really strong bias
towards finding these hot planets.
Now, hot planets are interesting.
The chemistry in their atmosphere is fascinating.
It’s very alien.
An example of one that’s particularly close to my heart
is TrES-2b, whose atmosphere is so dark,
it’s less reflective than coal.
And so they have really bizarre photometric properties,
yet at the same time,
they resemble nothing like our own home.
And so I said there’s two types of astrophysicists.
The astrophysicists who care about how the universe works.
They wanna understand the mechanics
of the machinery of this universe.
Why did the Big Bang happen?
Why is the universe expanding?
How are galaxies formed?
And there’s another type of astrophysicist,
which perhaps speaks to me a little bit more.
It whispers into your ear.
And that is, why are we here?
Are we alone?
Are there others out there?
And ultimately, along this journey,
the hot planets aren’t gonna get us there.
When we’re looking for life in the universe,
seems to make perfect sense
that there should be planets like our own out there.
Maybe even moons like our own planet
around gas giants that could be habitable.
And so my research has been driven
by trying to find these more traqueous globes
that might resemble our own planet.
So they’re the ones that lurk more in the shadows
in terms of how difficult it is to detect.
They’re much harder.
They’re harder for several reasons.
The method we primarily use is the transit method.
So this is really eclipses.
As the planet passes in front of the star,
it blocks out some starlight.
The problem with that is that not all planets
pass in front of their star.
They have to be aligned correctly from your line of sight.
And so the further away the planet is from the star,
the cooler it is, the less likely it is
that you’re gonna get that geometric alignment.
So whereas a hot Jupiter, about 1% of hot Jupiters
will transit in front of their star,
only about 0.5%, maybe even a quarter of a percent
of Earth-like planets will have
the right geometry to transit.
And so that makes it much, much harder for us.
What’s the connection between temperature of the planet
and geometric alignment,
probability of geometric alignment?
There’s not a direct connection,
but they’re connected via an intermediate parameter,
which is their separation from the star.
So the planet will be cooler
if it’s further away from the star,
which in turn means that the probability
of getting that alignment correct is going to be less.
On top of that,
they also transit their star less frequently.
So if you go to the telescope
and you want to discover a hot Jupiter,
you could probably do it in a week or so
because the orbital period is of order of one, two, three days
so you can actually get the full orbit
two or three times over.
Whereas if you want to detect an Earth-like planet,
you have to observe that star for three, four years.
And that’s actually one of the problems with Kepler.
Kepler was this very successful mission
that NASA launched over a decade ago now, I think.
And it discovered thousands of planets.
It’s still the dominant source of exoplanets
that we know about,
but unfortunately it didn’t last as long
as we would have liked it to.
It died after about 4.35 years, I think it was.
And so for an Earth-like planet,
that’s just enough to catch four transits.
Four transits was kind of seen as the minimum.
But of course, the more transits you see,
the easier it is to detect it
because you build up signal to noise.
If you see the same thing, tick, tick, tick, tick, tick,
the more ticks you get, the easier it is to find it.
And so it was really a shame
that Kepler was just at the limit
of where we were expecting it
to start to see Earth-like planets.
And in fact, it really found zero.
Zero planets that are around stars like the Sun,
that orbit similar to the Earth around the Sun,
and could potentially be similar to our own planet
in terms of its composition.
And so it’s a great shame,
but that’s why it gives astronomers
more to do in the future.
Just to clarify, the transit method
is our primary way of detecting these things.
And what it is, is when the object passes,
occludes the source of light just a tiny bit, a few pixels.
And from that, we can infer something
about its mass, and size, and distance,
and geometry, and all of that.
That’s like trying to tell, what?
At a party, you can’t see anything about a person,
but you can just see by the way they occlude others.
So this is the method.
But is this a super far away?
How many pixels of information do we have, basically?
How high resolution is the signal
that we can get about these occlusions?
You’re right in your description.
I think just to build upon that a little bit more,
it might be almost like your vision is completely blurry.
Like you have an extreme eye prescription,
and so you can’t resolve anything.
Everything’s just blurs.
But you can tell that something was there
because it just got fainter for a short amount of time.
Someone passed in front of a light.
And so that light in your eyes
would just dim for a short moment.
Now, the reason we have that problem
with blurriness or resolution
is just because the stars are so far away.
The closest stars are four light years away,
but most of the stars Kepler looked at
were thousands of light years away.
And so there’s absolutely no chance
that the telescope can physically resolve the star,
or even the separation between the planet and the star
is too small, especially for a telescope like Kepler.
It’s only a meter across.
In principle, you can make those detections,
but you need a different kind of telescope.
We call that direct imaging.
And direct imaging is a very exciting,
distinct way of detecting planets.
But it, as you can imagine,
is going to be far easier to detect planets
which are really far away from their star to do that,
because that’s gonna make that separation really big.
And then you also want the star to be really close to us,
so the nearest stars.
Not only that, but you would prefer that planet
to be really hot,
because the hotter it is, the brighter it is.
And so that tends to bias direct imaging
towards planets which are in the process of forming.
So things which have just formed,
the planet’s still got all of its primordial heat
embedded within it, and it’s glowing.
We can see those quite easily.
But for the planets more like the Earth,
of course, they’ve cooled down,
and so we can’t see that.
The light is pitiful compared to a newly formed planet.
We would like to get there with direct imaging.
That’s the dream, is to have the pale blue dot,
an actual photograph of it,
maybe even just a one-pixel photograph of it.
But for now, the entire solar system is one pixel,
certainly with the transit method
and most other telescopes.
And so all you can do is see where that one pixel,
which contains potentially dozens of planets,
and the star, maybe even multiple stars,
dims for a short amount of time.
It dims just a little bit,
and from that, you can infer something.
Yeah, I mean, it’s like being a detective in the scene,
right, it’s very, it’s indirect clues
of the existence of the planet.
It’s amazing that humans can do that.
We’re just looking out in these immense distances,
and looking, you know,
if there’s alien civilizations out there,
like let’s say one exactly like our own,
we’re like, would we even be able to see an Earth
that passes in the way of its sun and slightly dims?
And that’s the only sign we have
of that alien human-like civilization out there,
is it’s just a little bit of a dimming.
Yeah, I mean, it depends on the type of star we’re talking.
If it is a star truly like the sun,
the dip that causes is 84 parts per million.
I mean, that’s just, it’s like the same as a,
it’s like a firefly flying in front
of like a giant floodlight at a stadium or something.
That’s the kind of the brightness contrast
that you’re trying to compare to.
So it’s extremely difficult detection.
And in the very, very best cases, we can get down to that.
But as I said, we don’t really have any true Earth analogs
that have been in the exoplanet candidate yet.
Unless you relax that definition, you say,
it’s not just, doesn’t have to be a star just like the sun.
It could be a star that’s smaller than the sun.
It could be these orange dwarfs,
or even the red dwarf stars.
And the fact those stars are smaller means that
for the same size planet passing in front of it,
more light is blocked out.
And so a very exciting system, for example, is TRAPPIST-1,
which has seven planets, which are smaller than the Earth.
And those are quite easily detectable,
not with a space-based telescope,
but even from the ground.
And that’s just because the star is so much smaller
that the relative increase in or decrease in brightness
is enhanced significantly because that smaller size.
So TRAPPIST-1e, it’s a planet
which is in the right distance for liquid water.
It has a slightly smaller size than the Earth.
It’s about 90% the size of the Earth, about 80% the mass.
And it’s one of the top targets right now
for potentially having life.
And yet it raises many questions about
what would that environment be like?
This is a star which is one eighth the mass of the sun.
Stars like that take a long time
to come off their adolescence.
When stars first form, like the sun,
it takes them maybe 10, 100 million years
to sort of settle into that main sequence lifetime.
But for stars like these late M dwarfs, as we call them,
they can take up to a billion years or more to calm down.
And during that period,
they’re producing huge amounts of X-rays,
that could potentially rip off the entire atmosphere.
It may desiccate the planets in the system.
And so even if water arrived by comets or something,
it may have lost all that water
due to this prolonged period of high activity.
So we have lots of open-ended questions
about these M dwarf planets,
but they are the most accessible.
And so in the near term,
if we detect anything in terms of biosignatures,
it’s gonna be for one of these red dwarf stars,
it’s not gonna be a true Earth twin,
as we would recognize it as having a yellow star.
Well, let me ask you,
I mean, there’s a million ways to ask this question.
I’m sure I’ll ask it about habitable worlds.
Let’s just go to our own solar system.
What can we learn about the planets and moons
in our solar system that might contain life?
Whether it’s Mars or some of the moons of Jupiter
and Saturn, what kind of characteristics,
because you said it might not need to be Earth-like,
what kind of characteristics might we be looking for?
When we look for life,
it’s hard to define even what life is,
but we can maybe do a better job
in defining the sorts of things that life does.
And that provides some aspects to,
some avenue for looking for them.
In the, classically, conventionally,
I think we thought the way to look for life
was to look for oxygen.
Oxygen is a byproduct of photosynthesis on this planet.
We didn’t always have it.
Certainly if you go back to the Archean period,
there was, you have this period
called the Great Oxidation Event,
where the Earth floats with oxygen for the first time
and starts to saturate the oceans and then the atmosphere.
And so that oxygen, if we detect it on another planet,
whether it be Mars, Venus, or an exoplanet, whatever it is,
that was long thought to be evidence
for something doing photosynthesis.
Because if you took away all the plant life on the Earth,
the oxygen wouldn’t just hang around here
as a highly reactive molecule.
It would oxidize things.
And so within about a million years,
you would probably lose all the oxygen on planet Earth.
So that was conventionally
how we thought we could look for life.
And then we started to realize that it’s not so simple
because A, there might be other things that life does
apart from photosynthesis.
Certainly the vast majority of the Earth’s history
had no oxygen, and yet there was living things on it.
So that doesn’t seem like a complete test.
And secondly, could there be other things
that produce oxygen besides from life?
A growing concern has been these false positives
in biosignature work.
And so one example of that would be photolysis
that happens in the atmosphere.
When ultraviolet light hits the upper atmosphere,
it can break up water vapor.
The hydrogen splits off to the oxygen.
The hydrogen is a much lighter atomic species,
and so it can actually escape,
certainly planets like the Earth’s gravity.
That’s why we don’t have any hydrogen or very little helium.
And so that leaves you with the oxygen,
which then oxidizes the surface.
And so there could be a residual oxygen signature
just due to this photolysis process.
So we’ve been trying to generalize.
And certainly in recent years,
there’s been other suggestions,
things we could look for in the solar system beyond.
Nitrous oxide, basically laughing gas,
is a product of microbes.
That’s something that we’re starting
to get more interest in looking for.
Methane gas in combination with other gases
can be an important biosignature.
Phosphine as well, and phosphine’s particularly relevant
to the solar system because there was a lot of interest
for Venus recently.
You may have heard that there was a claim
of a biosignature in Venus’s atmosphere.
I think it was like two years ago now.
And the judge and jury are still out on that.
There was a very provocative claim and signature
of a phosphine-like spectral absorption.
But it could have also have been some other molecule
in particular, sulfur dioxide, which is not a biosignature.
So this is a detection of a gas in the atmosphere, Venus.
And it might be controversial in several dimensions.
So one, how to interpret that.
Two, is this the right gas?
And three, is this even the right detection?
Is there an error in the detection?
Yeah, I mean, how much do we believe
the detection in the first place?
If you do believe it, does that necessarily mean
there’s life there?
And what gives?
How can you have life in Venus’s atmosphere
in the first place?
That’s been seen as like a hellhole place
for imagining life.
But I guess the counter to that has been that,
okay, yes, the surface is a horrendous place
to imagine life thriving.
But as you go up in altitude,
the very dense atmosphere means that there is a cloud layer
where the temperature and the pressure
become actually fairly similar to the surface of the Earth.
And so maybe there are microbes stirring around
in the clouds, which are producing phosphine.
At the moment, this is fascinating.
It’s got a lot of us reinvigorated about the prospects
of going back to Venus and doing another mission there.
In fact, there’s now two NASA missions,
Veritas and Da Vinci, which are gonna be going back
and before 2030, the 2030s.
And then we have a European mission,
I think, that’s slated now,
and even a Chinese mission
might be coming along the way as well.
So we might have multiple missions going to Venus,
which has long been overlooked.
I mean, apart from the Soviets,
there really has been very little
in the way of exploration of Venus,
certainly as compared to Mars.
Mars has enjoyed most of the activity
from NASA’s rovers and surveys.
And Mars is certainly fascinating.
There’s this signature of methane
that has been seen there before.
Again, there, the discussion is whether that methane
is a product of biology, which is possible,
something that happens on the Earth,
or whether it’s some geological process
that we are yet to fully understand.
It could be, for example, a reservoir of methane
that’s trapped under the surface
and is leaking out seasonally.
So the nice thing about Venus is
if there’s a giant living civilization there,
it’ll be airborne, so you can just fly through
and collect samples.
With Mars and moons of Saturn and Jupiter,
you’re gonna have to dig under to find the civilizations,
dead or living.
Right, and so, yeah, maybe it’s easier then for Venus
because certainly you can imagine just a balloon
floating through the atmosphere,
or a drone or something that would have the capability
of just scooping up and sampling.
To dig under the surface of Mars is maybe feasible-ish,
especially with something like Starship
that could launch a huge digger, basically, to the surface
and you could just excavate away at the surface.
But for something like Europa,
we really are still unclear about how thick the ice layer is,
how you would melt through that huge thick layer
to get to the ocean,
and then potentially also discussions about contamination.
The problem with looking for life in the solar system,
which is different from looking for life with exoplanets,
is that you always run the risk of,
especially if you visit there,
of introducing the life yourself.
Right, it’s very difficult to completely exterminate
every single microbe and spore on the surface of your rover
or the surface of your lander,
and so there’s always a risk of introducing something.
I mean, to some extent, there is continuous exchange
of material between these planets,
naturally, on top of that as well,
and now we’re sort of accelerating that process
to some degree.
And so if you dig into Europa’s surface,
which probably is completely pristine,
it’s very unlikely there has been much exchange
with the outside world for its subsurface ocean,
you are, for the first time,
potentially introducing bacterial spores
into that environment that may compete
or may introduce spurious signatures
for the life you’re looking for.
And so it’s almost an ethical question
as to how to proceed with looking for life
on those subsurface oceans,
and I don’t think we really have a good resolution
for it at this point.
So you mean ethical in terms of concern
for preserving life elsewhere,
not to murder it, as opposed to a scientific one?
I mean, we always worry about a space virus
coming here or some kind of external source,
and we would be the source of that potential contamination.
Or the other direction.
I mean, whatever survives in such harsh conditions
might be pretty good at surviving in all conditions.
It might be a little bit more resilient and robust,
so it might actually take a ride on us back home.
I mean, I’m sure that some people
would be concerned about that.
I think we would hopefully have some containment procedures
as if we did sample return,
or I mean, you don’t even really need a sample return.
These days, you can pretty much send
like a little micro laboratory to the planet
to do all the experiments in situ,
and then just send them back to your planet, the data.
And so I don’t think this is necessary,
especially for a case like that,
where you might have contamination concerns
that you have to bring samples back.
Although, probably if you brought back European sushi,
it would probably sell for quite a bit
with the billionaires in New York City.
I would love from an engineering perspective
just to see all the different candidates
and designs for like the scooper,
for Venus and the scooper for Europa and Mars.
I haven’t really looked deeply into how they actually,
like the actual engineering of collecting the samples,
because the engineering of that is probably essential
for not either destroying life
or polluting it with our own microbes and so on.
So that’s like an interesting engineering challenge.
I usually, for rovers and stuff,
focus on the sort of the mobility aspect of it,
on the robotics, the perception,
and the movement and the planning and the control.
But there’s probably the scooper
is probably where the action is.
The microscopic sample collection.
So basically you have to first clean your vehicle,
make sure it doesn’t have any earth-like things on it.
And then you have to put it into some kind of thing
that’s perfectly sealed from the environment.
So if we bring it back or we analyze it,
it’s not going to bring anything else externally.
Yeah, I don’t know.
That would be an interesting engineering design there.
Yeah, I mean, Curiosity has been leaving
these little pods on the surface quite recently.
There’s some neat photos that you can find online.
And they kind of look like lightsaber hilts,
which is so, yeah, to me,
I think I tweeted something like,
this weapon is your life.
Like, don’t lose it, Curiosity,
because it’s just dumping these little vials everywhere.
And yeah, it is scooping up these things.
And the intention is that in the future
there will be a sample return mission
that will come and pick these up.
But it’s, I mean,
the engineering behind those things is so impressive.
The thing that blows me away the most has been the landings,
especially I’m trained to be a pilot at the moment.
So that’s the sort of,
watching landings has become like my pet hobby
on YouTube at the moment,
and how not to do it,
how to do it with different levels of conditions and things.
But when you think about landing on Mars,
just the light travel time effect
means that there’s no possibility
of a human controlling that descent.
And so you have to put all of your faith
and your trust in the computer code
or the AI or whatever it is that you’ve put on board that thing
to make the correct descent.
And so there’s this famous period called seven minutes of hell
where you’re basically waiting for that light travel time
to come back to know whether your vehicle successfully
landed on the surface or not.
And during that period,
you know in your mind simultaneously
that it is doing these multi-stages
of deploying its parachute, deploying the crane,
activating its jets to come down
and controlling its descent to the surface.
And then the crane has to fly away
so it doesn’t accidentally hit the rover.
And so there’s a series of multi-stage points
where any of them go wrong,
the whole mission could go awry.
And so the fact that we are fairly consistently able
to build these machines that can do this autonomously
is to me one of the most impressive acts of engineering
that NASA have achieved.
Yes, the unfortunate fact about physics
is the takeoff is easier than the landing.
And you mentioned Starship,
one of the incredible engineering feats
that you get to see is the reusable rockets
that take off but they land.
And they land using control and they do so perfectly.
And sometimes when it’s synchronous,
it’s just, it’s beautiful to see.
And then with Starship,
you see the chopsticks that catch the ship.
I mean, there’s just so much incredible engineering.
But you mentioned Starship is somehow helpful here.
So what’s your hope with Starship?
What kind of science might it enable possibly?
There’s two things.
I mean, it’s the launch cost itself,
which is hopefully gonna mean per kilogram,
it’s gonna dramatically reduce the cost of it.
Even if it’s a factor of 10 higher
than what Elon originally promised,
this is gonna be a revolution for the cost to launch.
That means you could do all sorts of things.
You could launch large telescopes,
which could be basically like JWST,
but you don’t even have to fold them up.
JWST had this whole issue with its design
that it’s six and a half meters across.
And so you have to, there’s no fuselage,
which is that large at the time.
The Ares IV wasn’t large enough for that.
And so they had to fold it up
in this kind of complicated origami.
And so a large part of the cost
was figuring out how to fold it up,
testing that it unfolded correctly,
And there was something like 130 fail points
or something during this unfolding mechanism.
And so all of us were holding our breath
during that process.
But if you have the ability to just launch
arbitrarily large masses,
at least comparatively compared to JWST,
and very large mirrors into space,
you can more or less repurpose ground-based mirrors.
The Hubble Space Telescope mirror and the JWST mirrors
are designed to be extremely lightweight,
and that increased their cost significantly.
They have this kind of honeycomb design on the back
to try and minimize the weight.
If you don’t really care about weight,
because it’s so cheap,
then you could just literally grab
many of the existing ground-based mirrors
across telescopes across the world,
four-meter, five-meter mirrors,
and just pretty much attach them to a chassis
and have your own space-based telescope.
I think the Breakthrough Foundation, for instance,
is an entity that has been interested
in doing this sort of thing.
And so that raises the prospects
of having not just one JWST,
that just, you know,
JWST is a fantastic resource,
but it’s split between all of us.
Cosmologists, star formation astronomers,
those of us studying exoplanets,
those of us wanting to study the ultra-deep fields
and the origin of the first galaxies,
the expansion of the universe.
Everyone has to share this resource,
but we could potentially each have one JWST each
that is maybe just studying a handful
of the brightest exoplanet stars
and measuring their atmospheres.
This is important because if you,
and we talked about this planet Trappist-1e earlier,
that planet, if JWST stared at it
and tried to look for biosignatures,
by which I mean oxygen, nitrous oxide, methane,
it would take it of order of 200 transits
to get even a very marginal,
what we’d call two and a half sigma detection of those,
which basically nobody would believe with that.
100 transits, this thing transits once every six days,
so you’re talking about four years
of staring at the same star with one telescope.
There’d be some breaks,
but it’d be hard to schedule much else
because you have to continuously catch
each one of these transits
to build up your signal-to-noise.
And so JWST’s never gonna do that.
In principle, technically, JWST could technically
have the capability of just about detecting a biosignature
on an Earth-like planet around a non-Sun-like star,
but still, impressively,
we have basically the technology to do that,
but we simply cannot dedicate all of its time practically
to that one resource.
And so Starship opens up opportunities like that
of mass-producing these kinds of telescopes,
which will allow us to survey for life in the universe,
which, of course, is one of the grand goals of astronomy.
I wonder if you can speak to the bureaucracy,
the political battles, the scientific battles
for time on the James Webb Telescope.
There must be a fascinating process of scheduling that.
All scientists, they’re trying to collaborate,
figure out what the most important problems are,
and there’s an interesting network
of interfering scientific experiments, probably,
they have to somehow optimize over.
It’s a really difficult process.
I don’t envy the tech
that are gonna have to make this decision.
We call it the tech, the time allocation committee
that make this decision.
And I’ve served on these before, and it’s very difficult.
Typically for Hubble, we were seeing at least 10,
sometimes 20 times the number of proposals
for telescope time versus available telescope time.
For GDST, there has been one call already
that has gone out, we call it cycle one,
and that was oversubscribed by,
I think something like six to one, seven to one.
And the cycle two, which has just been announced
fairly recently, and the deadline
is actually the end of this month,
so my team are totally laser-focused
on running our proposals right now.
That is expected to be much more competitive,
probably more comparable to what Hubble saw.
And so, it’s hard.
More competitive than the cycle one, you said, already?
Because that’s already super competitive.
More competitive than the first cycle.
So I said the first cycle of James Webb
was about six to one, and this will probably be more like
20 to one, I would expect.
So these are all proposals by scientists and so on,
and it’s not like you can schedule at any time,
because if you’re looking for transit times.
Yeah, you have a time-critical element.
Yes, time-critical element.
And they’re conflicting in non-obvious ways,
because the frequency is different,
the duration is different,
there’s probably computational needs that are different,
there’s the type of sensors, the direction pointing,
Yeah, it’s hard, and there are certain programs
like doing a deep field study,
where you just more or less point the telescope,
and that’s pretty open.
I mean, you’re just accumulating photons.
You can just point at that patch of the sky,
whenever the telescope’s not doing anything else,
and just get to your month,
let’s say a month of integration time is your goal
over the lifetime of JWST.
So that’s maybe a little bit easier to schedule.
It’s harder, especially for us looking at cool worlds,
because as I said earlier,
these planets transit very infrequently.
So we have to wait.
If you’re looking at the Earth transiting the Sun,
an alien watching us,
they would only get one opportunity per year
to do that observation.
The transit lasts for about 12 hours.
And so if they don’t get that time, it’s hard.
If it conflicted with another proposal
that wants to use another time-critical element.
It’s much easier for planets like these hot planets
or these close-in planets,
because they transit so frequently,
there’s maybe 100 opportunities.
And so then the TAT can say, okay, they want 10 transits.
There’s 100 opportunities here.
It’s easier for us to give them time.
We’re almost in the worst-case scenario.
We’re proposing to look for exoplanets
around two cool planets.
And so we really only have one bite of the cherry
for each one.
And so our sales pitch has been
that these are extremely precious events.
And more importantly, JWST is the only telescope,
the only machine humanity has ever constructed,
which is capable of finding moons
akin to the moons in our solar system.
Kepler can’t do it.
Even Hubble can’t do it.
JWST is the first one.
And so there is a new window to the universe,
because we know these moons exist.
They’re all over the place in the solar system.
You have the Moon, you have Io, Callisto,
Europa, Ganymede, Titan.
Lots of moons of fairly similar size,
sort of 30% the size of the Earth.
And this telescope is the first one that can find them.
And so we’re very excited about the profound implications
of ultimately solving this journey we’re on in astronomy,
which is to understand our uniqueness.
We want to understand how common is the solar system,
are we the architecture that frequently emerges naturally,
or is there something special about what happened here?
I think this is not the worst case, it’s the best case.
It’s obvious, it’s super rare.
I love scheduling from a computer science perspective.
That’s my background.
So algorithmically, to solve a schedule problem,
I will schedule the rarest things first.
And obviously, JWST is the first thing
that can actually detect a cool world.
So this is a big new thing.
You can show off that new thing.
Happens rarely, schedule it first, it’s perfect.
You should be in the TAC, this is perfect.
I will, I’ll file my application
after we’re done with this.
This part of me is the OCD,
part of me is the computational aspect.
I love scheduling.
Computing device, because you have that kind of scheduling
on supercomputers, that scheduling problem’s fascinating.
How do you prioritize computation?
How do you prioritize science?
Data collection, sample collection,
all that kind of stuff.
That’s actually kind of fascinating,
because data, in ways you expect and don’t expect,
will unlock a lot of solutions
to some fascinating mysteries.
And so collecting the data and doing so
in a way that maximizes the possibility of discovery
is really interesting, from a computational perspective.
I agree, there’s a real satisfaction
extracting the maximum science per unit time
out of your telescope.
That’s the TAC’s job.
But the TAC are not machines,
they’re not a piece of computer code.
They will make their selections based off human judgment.
And a lot of the telescope,
certainly within the field of exoplanets,
because there’s different fields of astronomy,
but within the field of exoplanets,
I think a good expectation is that most of the telescope time
that JWC have will go towards atmospheric retrieval,
which is sort of alluded to earlier,
like detecting molecules in the atmospheres,
not biosignatures, because as I said,
it’s really not designed to do that.
It’s pushing JWST probably too far to expect it to do that.
But it could detect, for example,
a carbon dioxide rich atmosphere on TRAPPIST-1e.
That’s not a biosignature,
but you could prove it’s like a Venus in that case,
or maybe like a Mars in that case,
like both those have carbon dioxide rich atmospheres.
Doesn’t prove or disprove the existence of life either way,
but it is our first characterization
of the nature of those atmospheres.
Maybe we can even tell the pressure level
and the temperature of those atmospheres.
So that’s very exciting.
But we are competing with that.
And I think that science
is completely mind-blowing and fantastic.
We have a completely different objective,
which is in our case to try and look for the first evidence
of these small moons around these planets,
potentially even moons which could be habitable, of course.
So I think it’s a very exciting goal,
but ATT&CK has to make a human judgment
essentially about which science are they most excited by,
which one has the highest promise of return,
the most highest chance of return.
And so that’s hard,
because if you look at a planetary atmosphere,
well, you know most of the time
the planet has an atmosphere already.
And so there’s almost a guaranteed success
that you’re gonna learn something about the atmosphere
by pointing judiciously at it.
Whereas in our case, there’s a harder sell.
We are looking for something
that we do not know for sure exists yet or not.
And so we are pushing the telescope to do something
which is inherently more risky.
Yeah, but the existence, if shown,
already gives a deep lesson
about what’s out there in the universe.
That means that other stars have similar types of variety
as we have in our solar system.
They have an Io, they have a Europa and so on,
which means there’s a lot of possibility
for icy planets, for water,
for planets that enable planets and moons.
I mean, that’s super exciting,
because that means everywhere through our galaxy and beyond
that there is just innumerable possibility
for weird creatures.
You don’t have to convince me.
I mean, NASA has been on this quest for a long time
and it’s sometimes called Eater Earth.
It’s the frequency of Earth-like,
usually they say planets, in the universe.
How common are planets similar to our Earth?
In terms of, ultimately,
we’d like to know everything about these planets
in terms of the amount of water they have,
how much atmosphere they have.
But for now, it’s kind of focused just on the size
and the distance from the star, essentially.
How often do you get similar conditions to that?
That was Kepler’s primary mission
and it really just kind of flirted with the answer.
It didn’t quite get to a definitive answer.
But I always say, look, if that’s our primary goal,
to look for Earth-like, I would say, worlds,
then moons has to be a part of that.
Because we know that Earth-like,
from the Kepler data, the preliminary result
is that Earth-like planets around sun-like stars
is not an inevitable outcome.
It seems to be something like a one to 10% outcome.
So it’s not particularly inevitable that that happens.
But we do often see about half of all sun-like stars
have either a mini-Neptune, a Neptune, or a Jupiter
in the habitable zone of their stars.
That’s a very, very common occurrence that we see.
Yet we have no idea how often they have moons around them,
which could also be habitable.
And so there may very well be,
if even one in five of them has an Earth-like moon
or even a Mars-like moon around them,
then there would be more habitable real estate
in terms of exomoons than exoplanets in the universe.
Essentially, 2x, 3x, 5x, maybe 10x,
the number of habitable worlds out there in the universe.
Our current estimate, like the Drake equation.
So this is one way to increase the confidence
and increase the value of that parameter.
And just know where to look.
I mean, we would like to know
where should we listen for technosignatures?
Where should we be looking for biosignatures?
And not only that, but what role does the moon have
in terms of its influence on the planet?
We talked about these directly imaged telescopes earlier,
these missions that want to take a photo
to quote Carl Sagan, the pale blue dot of our planet,
but the pale blue dot of an exoplanet.
And that’s the dream, to one day capture that.
But as impressive as the resolution is
that we are planning and conspiring to design
for the future generation telescopes to achieve that,
even those telescopes will not have the capability
of resolving the Earth and the moon within that.
It’ll be a pale blue dot pixel,
but the moon’s grayness will be intermixed with that pixel.
And so this is a big problem,
because one of the ways that we are claiming
to look for life in the universe
is a chemical disequilibrium.
So you see two molecules that just shouldn’t be there.
They normally react with each other.
Or even one molecule that’s just too reactive
to be hanging around the atmosphere by itself.
So if you had oxygen and methane hanging out together,
those would normally react fairly easily.
And so if you detected those two molecules
in your pale blue dot spectra,
you’d be like, okay, we have evidence for life.
Something’s metabolizing on this planet.
However, the challenge here is what if that moon was Titan?
Titan has a methane-rich atmosphere.
And what if the pale blue dot
was in fact a planet devoid of life,
but it had oxygen because of water
undergoing this photolysis reaction,
splitting into oxygen and hydrogen separately?
So then you have all of the hallmarks
of what we would claim to be life.
But all along you were tricked.
It was just a moon that was deceiving you.
And so we are never going to,
we’re never going to, I would claim,
really understand or complete this quest
of looking for life by signatures in the universe
unless we have a deep knowledge of the prevalence
and role that moons have.
They may even affect the habitability
of the planets themselves.
Of course, our own moon is freakishly large.
By mass ratio, it’s the largest moon in the solar system.
It’s a 1% mass moon.
If you look at Jupiter’s moons,
they’re like 10 to the power minus four, much smaller.
And so our own moon seems to stabilize
the obliquity of our planet.
It gives rise to tides,
especially early on when the moon was closer,
those tides would have covered entire continents.
And those rock pools that would have been scattered
across the entire plateau
may have been the origin of life on our planet.
The moon forming impact may have stripped
a significant fraction of lithosphere off the Earth,
which without it, plate tectonics may not have been possible.
We’d have had a stagnant lid
because there was just too much lithosphere
stuck on the top of the planet.
And so there are speculative reasons,
but intriguing reasons as to why a large moon
may be not just important,
but central to the question
of having the conditions necessary for life.
So moons can be habitable in their own right,
but they can also play a significant influence
on the habitability of the planets they orbit.
And further, they will surely interfere
with our attempts to detect life remotely from afar.
So taking a tangent upon a tangent,
you’ve written about binary planets.
What’s, and that they’re surprisingly common,
or they might be surprisingly common.
What’s the difference between a large moon
and binary planets?
What are binary planets?
What’s interesting to say here
about giant rocks flying through space
and orbiting each other?
The thing that’s interesting about binary objects
is that they’re very common in the universe.
Binary stars are everywhere.
In fact, the majority of stars
seem to live in binary systems.
When we look at the outer edges of the solar system,
we see binary Kuiper Belt objects all the time.
Asteroids basically bound to one another.
Pluto-Charon is kind of an example of that.
It’s a 10% mass ratio system.
It almost is, by many definitions, a binary planet,
but now it’s a dwarf planet.
So I don’t know what you’d call that now.
But we know that the universe likes to make things in pairs.
So you’re saying our sun is an incel.
It’s looking, so most things are dating,
they’re in relationships, and ours is alone.
It’s not a complete freak of the universe to be alone,
but it’s more common for sun-like stars.
If you count up all the sun-like stars in the universe,
about half of the sun-like star systems
are in binary or trinary systems,
and the other half are single.
But because those binaries are two or three stars,
then cumulatively, maybe a third of all sun-like stars
I’m trying hard to not anthropomorphize
the relationship the stars have with each other.
Yeah, I’ve met those folks also.
So is there something interesting to learn
about the habitability, how that affects the probability
of habitable worlds when they kind of couple up like that
in those different ways?
It depends which way the stars of the planet.
Certainly, if stars couple up,
that has a big influence on the habitability.
Of course, this is very famous from Star Wars.
Tatooine in Star Wars is a binary star system,
and you have Luke Skywalker looking at the sunset
and seeing two stars come down.
And for years, we thought that was purely a product
of George Lucas’s incredibly creative mind,
and we didn’t think that planets would exist
around binary star systems.
It seems like too tumultuous an environment
for a quiescent planetary disc,
circumstellar disc to form planets from.
And yet, one of the astounding discoveries from Kepler
was that these appear to be quite common.
In fact, as far as we can tell,
they’re just as common around binary stars as single stars.
The only caveat to that is that you don’t get planets
close into binary stars.
They have like a clearance region on the inside
where planets, maybe they form there, but they don’t last.
They are dynamically unstable in that zone.
But once you get out to about the distance
that the Earth orbits the Sun,
or even a little bit closer in,
you start to find planets emerging.
And so, that’s the right distance for liquid water,
it’s the right distance for potentially life
on those planets.
And so, there may very well be plenty of habitable planets
around the binary stars.
Binary planets is a little bit different.
Binary planets, I don’t think we have any serious connection
of planet banality to habitability.
Certainly when we investigated it, that wasn’t our drive,
that this is somehow the solution
to life in the universe or anything.
It was really just a, like all good science questions,
a curiosity-driven question.
What’s the dynamic?
Are they legit orbiting each other
as they orbit the star?
So, the formation mechanism proposed here,
because it is very difficult to form two proto-planets
close to each other like this.
They would generally merge within the disk,
and so that’s why you normally get single planets.
But you could have something like Jupiter and Saturn
form at separate distances.
They could dynamically be scattered in towards one another
and basically not quite collide,
but have a very close-on encounter.
Now, because tidal forces increase dramatically
as the distance decreases between two objects,
the tides can actually dissipate the kinetic energy
and bring them bound into one another.
So, that seems, when you first hear that,
you think, well, that seems fairly contrived
that you’d have the conditions just right
to get these tides to cause a capture.
But numerical simulations have shown that about 10%
of planet-planet encounters are shown to produce
something like binary planets,
which is a startling prediction.
And so, that seems at odds with, naively,
the exoplanet catalogue, for which we know of,
so far, no binary planets.
And we propose one of the resolutions to this
might be that the binary planets
are just incredibly difficult to detect,
which is also counterintuitive,
because, remember how they form
is through this tidal mechanism,
and so they form extremely close to each other.
So, the distance that Io is away from Jupiter,
just a few planetary radii,
they’re almost touching one another,
and they’re just tidally locked,
facing each other for eternity.
And so, in that configuration,
as it transits across the star,
it kind of looks like you can’t really resolve
those two planets.
It just looks like one planet to you
that’s going across the star.
The temporal resolution of the data
is rarely good enough to distinguish that.
And so, you’d see one transit,
but in fact, it’s two planets very close together,
which are transiting at once.
And so, yeah, we wrote a paper just recently
where we developed some techniques
to try and get around this problem,
and hopefully provide a tool
where we could finally look for these planets.
The problem of detection of these planets
when they’re so close together.
That was our focus, was how do you get around
this merging problem?
So, whether they’re out there or not,
we don’t know.
We’re planning to do a search for them,
but it remains an open question.
And I think just one of those fun
astrophysics curiosities questions,
whether binary planets exist in the universe.
Because then you have binary Earths,
you could have binary Neptune,
all sorts of wild stuff that would
float the sci-fi imagination.
I wonder what the physics on a binary planet feels like.
It might be trivial.
I have to think about that.
I wonder if there’s some interesting dynamics.
Like, if you have multiple,
or would gravity feel different
at different parts of the surface of the sphere
when there’s another large sphere that’s interesting?
Yeah, I would think that the force
would be fairly similar,
because the shape of the object
would deform to a flat geopotential,
essentially, a uniform geopotential.
But it would lead to a distorted shape
for the two objects.
I think they’d become ellipsoids facing one another.
So, it would be pretty wild when you,
people like flat Earth or spherical Earth,
you fly from space and you see a football-shaped Earth.
It’s your own planet.
Finally, there’s proof.
And I wonder how difficult it would be
to travel from one to the other,
because you have to overcome the one.
No, it might be kind of easy.
Yeah, I mean, they’re so close to each other, that helps.
And I think the most critical factor
would be how massive is the planet?
That’s always, I mean,
one of the challenges with escaping planets,
there was a fun paper one of my colleagues wrote
that suggested that super-Earth planets may be inescapable.
If you’re a civilization that were born on a super-Earth,
the surface gravity is so high
that the chemical potential energy of hydrogen
or methane, whatever fuel you’re using,
simply is at odds with the gravity of the planet itself.
And so you would, you know,
our current rockets, I’m not sure of the fraction,
but maybe like 90% of the rocket is fuel or something
These things would have to be,
like the size of the Giza pyramids of fuel
with just a tiny tip on the top
in order just to escape that planetary atmosphere.
And so it has been argued that if you live on a super-Earth,
you may be forced to live there forever.
There may be no escape
unless you invent a space elevator or something,
but then how do you even build the infrastructure in space
to do something like that
in the absence of a successful rocket program?
And so the more and more we look at our Earth
and think about the sorts of problems we’re facing,
the more you see things about the Earth
which make it ideally suited in so many regards.
It’s almost spooky, right,
that we not only live on a planet
which has the right conditions for life,
for intelligent life,
for sustained fossil fuel industry
just happens to be in the ground.
We have plenty of fossil fuels
to get our industrial revolution going,
but also the chemical energy contained
within those fossil fuels and hydrogen and other fuels
is sufficient that we have the ability
to escape our planetary atmosphere and planetary gravity
to have a space program.
And we also happen to have a celestial body
which is just within reach, the Moon,
which doesn’t also necessarily have to be true.
Were the Moon not there,
what effect would that have had
on our aspirations of a space program in the 1960s?
Would there have ever been a space race to Mars or to Venus?
It’s a much harder, certainly for a human program,
that seems almost impossible with 1960s technology
to ever come to fruition.
It’s almost as if somebody constructed
a set of challenging obstacles before us,
challenging problems to solve.
They’re challenging, but they’re doable.
And there’s a sequence to them.
Gravity is very difficult to overcome,
but we have, given the size of Earth,
it’s not so bad that we can still actually
construct propulsion systems that can escape it.
Yeah, and the same with climate change, perhaps.
I mean, climate change is the next major problem
facing our civilization,
but we know it is technically surmountable.
You know, it does seem sometimes
like there has been a series of challenges laid out
to progress us towards a mature civilization
that can one day perhaps expand to the stars.
I’m a little more concerned about nuclear weapons,
AI, and natural or artificial pandemics,
but yes, climate change.
Yeah, well, there you go.
I mean, plenty of milestones that we need to cross.
And we can argue about the severity of each of them,
but there is no doubt that we live in a world
that has serious challenges
that are pushing our intellects and our will
to the limit of whether we’re really ready
to progress to the next stage of our development.
So thank you for taking the tangent,
and there’ll be a million more,
but can we step back to Kepler-1625b?
What is it?
And you’ve talked about this kind of journey,
this effort to discover exomoons,
so moons out there, or small, cool objects out there.
Where does that effort stand,
and what is Kepler-1625b?
Yeah, I mean, I’ve been searching for exomoons
for most of my professional career,
and I think a lot of my colleagues think
I’m kind of crazy to still be doing it.
You know, after five years of not finding anything,
I think most people would probably
try doing something else.
I even had people say that to me.
They said, you know, professors,
and I remember at a cocktail party,
took me to the side, an MIT professor,
and he said, you know,
you should just look for hot Jupiters.
It’s really, you can write papers.
They’re so easy to find.
And I was like, yeah, but hot Jupiters just,
they’re not interesting to me.
I wanna do something that I feel
intellectually pushes me to the edge,
and it’s maybe a contribution
that not no one else could do,
but maybe is not certainly the thing
that anybody could do.
I don’t wanna just be the first to something
for the sake of being first.
I wanna do something that feels like
a meaningful intellectual contribution to our society.
And so, you know, this exomoon problem
has been haunting me for years to try and solve this.
Now, as I said, we looked for years and years using Kepler,
and the closest we ever got was just a hint
for this one star, Kepler-1625,
has a Jupiter-like planet in orbit of it,
and that Jupiter-like planet is on a 287-day period,
so it’s almost the same distance
as the Earth around the Sun, but for a Jupiter.
So that was already unusual.
I don’t think people realize that Jupiter-like planets
are quite rare in the universe.
Certainly mini-Neptunes and Neptunes are extremely common,
but Jupiters, only about 10% of Sun-like stars
have Jupiters around them, as far as we can tell.
When you say Jupiter, which aspect of Jupiter?
In terms of its mass and its semi-major axis.
So anything beyond about half an AU,
so half the distance of the Earth and the Sun,
and something of order of a tenth of a Jupiter mass,
that’s the mass of Saturn, up to, say, 10 Jupiter masses,
which is basically where you start to get to brown dwarfs,
those types of objects appear to be somewhat unusual.
Most solar systems do not have Jupiters,
which is really interesting, because Jupiter, again,
like the Moon, seems to have been a pivotal character
in the story of the development of our solar system,
perhaps especially having a large influence
on the development of the late heavy bombardment
and the rate of asteroid impacts
that we receive and things like this.
Anyway, to come back to 1625,
this Jupiter-like planet had a hint
of something in the data.
But what I mean by that is when we looked at the transit,
we got the familiar decrease in light
that we always see when a planet tries to confront the star,
but we saw something extra, just on the edges,
we saw some extra dips around the outside.
It was right at the hairy edge of detectability.
We didn’t believe it, because I think one of the challenges
of looking for something for 10 years
is that you become your own greatest skeptic.
And no matter what you’re shown,
you’re always thinking,
I’ve been falling in love so many times,
and it’s not working out.
You convince yourself it’s never gonna happen.
Not for me, this just isn’t gonna happen.
And so I saw that, and I didn’t really believe it,
because I didn’t dare let myself believe it.
But being a good scientist,
we knew we had an obligation to publish it,
to talk about the result, and to follow it up,
and to try and resolve what was going on.
So we asked for Hubble Space Telescope time,
which was awarded in that case.
So we were one of those lucky 20 that got telescope time.
And we studied it for about 40 hours continuously.
And to provide some context,
the dip that we saw in the Kepa data
corresponded to a Neptune-sized moon
around a Jupiter-sized planet,
which was another reason why I was skeptical.
We don’t have that in the solar system.
That seems so strange.
And then when we got the Hubble data,
it seemed to confirm exactly that.
There was two really striking pieces of evidence
in the data that suggested this moon was there.
Another was a fairly clear second dip in light,
pretty clearly resolved by Hubble.
It was about a five-sigma detection.
And on top of that,
we could see the planet didn’t transit
when it should have done.
It actually transited earlier than we expected it to,
by about 20 minutes or so.
And so that’s a hallmark of a gravitation interaction
between the planet and the moon.
We actually expected that.
You can also expect that if the moon transits
after the planet,
then the planet should come in earlier than expected,
because the barycenter, the center of mass,
lives between the two of them,
kind of like on a balancing arm between them.
And so we saw that as well.
So the phase signature matched up.
The mass of the moon was measured to be Neptune mass,
and the size of the moon was measured to be Neptune radius.
And so everything just really lined up.
And we spent months and months trying to kill it.
This is my strategy for anything interesting.
We just try to throw the kitchen sink at it and say,
we must be tricked by something.
And so we tried looking at the centroid motion
of the telescope,
but the different wavelength channels have been observed,
the pixel level information.
And no matter what we did, we just couldn’t get rid of it.
And so we submitted it to Science.
And I think at the time,
Science, which is one of the top journals, said to us,
would you mind calling your paper discovery of an exomoon?
And I had to push back.
And we said, no, we’re not calling it that.
I don’t, even despite everything we’ve done,
we’re not calling it a discovery.
We’re calling it evidence for an exomoon.
Because for me, I’d wanna see this repeat
two times, three times, four times
before I really would bet my house
that this is the real deal.
And I do worry, as I said,
that perhaps that’s my own self-skepticism going too far.
But I think it was the right decision.
And since that paper came out,
there has been continuous interest in the subject.
Another team independently analyzed that star
and recovered actually pretty much exactly
the same results as us, the same dip,
the same wobble of the planet.
And a third team looked at it
and actually got something different.
They saw the dip was diminished compared to what we saw.
They saw a little hint of a dip,
but not as pronounced as what we saw.
And they saw the wobble as well.
So there’s been a little bit of tension
about analyzing the reduction of the Hubble data.
And so the only way in my mind to resolve this
is just to look again.
We actually did propose to Hubble straight after that.
And we said, look, if our model is right,
if the moon is there, it came in late last time.
It transited after the planet.
Because of the orbit,
we can calculate that it should transit
before the planet next time.
If it’s not there, if it doesn’t transit before,
and even if we see a dip afterwards,
we know that’s not our moon.
It’s obviously some instrumental effect with the data.
We had a causal prediction as to where the moon should be.
And so I was really excited about that,
but we didn’t get the telescope time.
And unfortunately, if you go further into the future,
we no longer have the predictive capability
because it’s like predicting the weather.
You might be able to predict the weather next week
to some level of accuracy,
but predicting the weather next year becomes incredibly hard.
The uncertainties just grow and compound
as you go forward into the future more and more.
How were you able to know
where the moon would be positioned?
So you’re able to tell the orbiting geometry and frequency?
Yeah, so basically from the wobbles of the planet itself,
that tells us the orbital motion of the moon.
It’s the reflex motion of the moon on the planet.
Isn’t it just an estimate to where,
like I’m concerned about you making a strong prediction here
because if you don’t get the moon
where the moon leads on the next time around,
if you did get Hubble time,
couldn’t that mean something else if you didn’t see that?
Because you said it would be an instrumental.
I feel the strong urge to disprove your own,
which is a really good imperative.
It’s a good way to do science,
but like this is such a noisy signal, right?
Or blurry signal, maybe.
Low resolution signal, maybe.
Yeah, I mean, it’s a five sigma signal.
That’s at the slightly uncomfortable edge.
I mean, it’s often said that for any detection
of a first new phenomena,
you really want like a 20, 25 sigma detection.
Then there’s just no doubt that what you’re seeing is real.
This was at that edge.
I mean, I guess it’s comparable to the Higgs boson,
but the Higgs boson was slightly different
because there was so much theoretical impetus
as to expect a signal at that precise location.
A Neptune-sized moon was not predicted by anyone.
No one, there was no papers you can find
that expect Neptune-sized moons around Jupiter-sized planets.
So I think we were inherently skeptical
about its reality for that reason.
But this is science in action.
When we fit the wobbles, we fit the dips,
and we have this 3G geometric model
for the motion of the orbit,
and projecting that forward,
we found that about 80% of our projections
led to the moon to be before.
So it’s not 100%.
There was maybe 20% of the cases it was over here.
But to me, that was a hard enough projection
that we felt confident that we could refute the,
which was what I really wanted.
I wanted a refutable,
that’s the basis of science,
a falsifiable hypothesis.
How can you make progress in science
if you don’t have a falsifiable testable hypothesis?
And so that was the beauty of this particular case.
So there’s a numerical simulation with a moon
that fits the data that we observed,
and then you can now make predictions
based on that simulation.
That’s so cool.
These are like little solar systems
that we can simulate on the computer
and imagine their motions.
But we are pushing things
to the very limits of what’s possible,
and that’s double-edged sword.
It’s both incredibly exciting intellectually,
but you’re always risking, to some degree,
the pushing too far.
So I’d like to ask you about the recent paper
an exomoon survey of 70 cool giant exoplanets
and the new candidate Kepler 1708 Bi.
I would say there’s like three or four candidates
at this point,
of which we have published two of them.
And to me, two are quite compelling
and deserve follow-up observations.
And so to get a confirmed detection,
at least in our case,
we would need to see it repeat, for sure.
One of the problems with some of the other methods
that have been proposed
is that you don’t get that repeatability.
So for instance, an example of a technique
that would lack that
would be gravitational microlensing.
So it is possible with a new telescope
coming up in the future
called the Roman Space Telescope,
which is basically a repurpose by satellite
that’s the size of the Hubble mirror
going up into space.
It will stare at millions of stars simultaneously
and it will look to see,
instead of whether any of those stars
get dimmer for a short amount of time,
which would be a transit,
it’ll look for the opposite.
It’ll look to see if anything can get brighter.
And that brightness increase
is caused by another planetary system passing in front
and then gravitationally lensing light around it
to cause a brightening.
This is a method of discovering an entire solar system,
but only for a glimpse.
You just get a short glimpse of it
passing like a ship sailing through the night,
just that one photo of it.
Now the problem with that is that
it’s very difficult.
The physics of gravitational lensing
are not surprisingly quite complicated.
And so there’s many, many possible solutions.
So you might have a solution
which is this could be a red dwarf star
with a Jupiter-like planet around it.
That’s one solution.
But another solution is that it’s a free-floating planet,
a rogue planet like Jupiter
with an Earth-like moon around it.
And those two solutions are almost indistinguishable.
Now, ideally, we would be able to repeat the observation.
We’d be able to go back and see,
well, if the moon really is there,
then we could predict its mass,
it’s predicted its motion
and expect it to be maybe over here next time or something.
With microlensing, it’s a one snapshot event.
And so, for me, it’s intriguing
as a way of revealing something
about the exomoon population.
But I always come back to transits
because it’s the only method we really have
that’s absolutely repeatable,
that we’ll be able to come back and prove everyone,
prove to everyone that, look,
on the 17th of October, the moon will be over here
and the moon will look like this
and we can actually capture that image.
And that’s what we see with, of course, many exoplanets.
So we wanna get to that same point of full confidence,
full confirmation, the slam-dunk detection
of these exomoons.
But yeah, it’s been a hell of a journey
to try and push the field into that direction.
Is there some resistance to the transit method?
Not to the transit method, I just say to exomoons.
So the transit method is by far the most popular method
for looking for exoplanets.
But yeah, as I’ve alluded to,
exomoons is kind of a niche topic
within the discipline of exoplanets.
And that’s largely because there are people,
I think, are waiting for those slam-dunks.
And it was like the,
if you go back to the first exoplanet discovery
that was made in 1995 by Michel Mayor and Didier Queloz,
I think it’s true at the time
that they were seen as mavericks,
that the idea of looking for planets around stars
was considered fringe science.
And I’m sure many colleagues told them,
why don’t you do something more safe,
like study eclipsing stars?
There are two binary star systems, we know those exist.
So why are you wasting your time looking for planets?
You’re gonna get this alien moniker or something,
and you’ll be seen as a fringe maverick scientist.
And so I think it was quite difficult
for those early planet hunters to get legitimacy
and be taken seriously.
And so very few people risked their careers to do it,
except for those that were either emboldened to try
or had maybe the career, maybe like tenure or something,
so they didn’t have to necessarily worry
about the implications of failure.
And so once that happened,
once they made the first discoveries,
overnight, everyone and their dog
was getting into exoplanets,
and all of a sudden the whole astronomy community shifted
and huge numbers of people
that were once upon a time studying eclipsing binaries
changed to becoming exoplanet scientists.
And so that was the first wave of exoplanet scientists.
We’re now in a kind of a second wave,
or maybe a third wave,
where people like me to some degree
grew up with the idea of exoplanets as being normal.
I was 11 years old, I guess,
when the first exoplanet was discovered.
And so to me, it was a fairly normal idea to grow up with.
And so we’ve been trained in exoplanets
from the very beginning.
And so that brings a different perspective
to those who have maybe transitioned
from a different career path.
And so I suspect with exomoons
and probably technosignatures, astrobiology,
many of the topics which are seen
at the fringes of what’s possible,
they will all open up into becoming mainstream one day.
But there’s a lot of people who are just waiting,
waiting for that assuredness
that there is a secure career net ahead of them
before they commit.
Yeah, it does seem to me that exomoons open wider
or open for the first time the door to aliens.
So more seriously, academically studying,
all right, let’s look at alien worlds.
So I think it’s still pretty fringe
to talk about alien life,
even on Mars and the moons and so on.
You’re kind of like, it would be nice,
but imagine the first time you discover a living organism.
That’s gonna change.
Then everybody will look like an idiot
for not focusing everything on this.
Because the possibility of the things will,
it’s possible it might be super boring.
It might be very boring bacteria.
But even the existence of life elsewhere,
I mean, that changes everything.
That means life is everywhere.
If you knew now that in five years, 10 years,
the first life would be discovered elsewhere,
you knew that in advance,
it would surely affect the way
you approach your entire career.
Especially someone junior in astronomy,
you would surely be like,
well, this is clearly gonna be the direction
I have to dedicate my classes and my training
and my education towards that direction.
All the new textbooks, all the-
You have to be written.
And I think there’s a lot of value to hedging,
like allocating some of the time to that possibility.
Because the kind of discoveries we might get
in the next few decades,
it feels like we’re on the verge of a lot of,
getting a lot of really good data
and having better and better tools
that can process that data.
So there’s just going to be a continuous increase
of the kind of discoveries that will open.
But a slam dunk, that’s hard to come by.
Yeah, I think a lot of us are anticipating,
I mean, we’re already seeing it to some degree
with Venus and the phosphine incident.
But we’ve seen it before with Bill Clinton.
It’s on the White House lawn announcing life from Mars.
And there are inevitably gonna be spurious claims,
or at least claims which are ambiguous to some degree.
There will be, for sure, a high profile journal,
like Nature or Science, that will one day publish a paper
saying, by a signature discovered or something like that
on Trappist-1 or some other planet.
And then there will be years of back and forth
in the literature.
And that might seem frustrating,
but that’s how science works.
That’s the mechanism of science at play,
of people scrutinizing the results
to intense skepticism.
And it’s like a crucible.
You burn away all irrelevances
until whatever is left is the truth.
And so you’re left with this product,
which is that, okay, we either believe or don’t believe
that bite signatures are there.
So there’s inevitably gonna be a lot of controversy
and debate and argument about it.
We just have to anticipate that.
And so I think you have to basically have a thick skin,
to some degree, academically, to dive into that world.
And you’re seeing that with phosphine.
It’s been uncomfortable to watch from the outside
the kind of dialogue that some of the scientists
have been having with each other about that, because-
They get a little aggressive.
Yeah, and you can understand why, because-
I don’t know.
That’s me saying, not you.
That’s me talking.
I’m sure there’s some envy and jealousy involved
on the behalf of those who are not part
of the original discovery.
But there’s also, in any case,
just leave the particular people involved in Venus alone,
in any case of making a claim of that magnitude,
especially life, because life is pretty much
one of the biggest discoveries of all time,
you can imagine, scientifically, you can see,
and I’m so conscious of this in myself,
when I get close to, as I said,
even the much smaller goal of setting an exomoon,
the ego creep in.
And so, as a scientist, we have to be so guarded
against our own egos.
You see the lights in your eyes of a Nobel Prize,
or the fame and fortune and being remembered
in the history books, and we all grew up in our training,
learning about Newton and Einstein,
these giants of the field, Feynman, Maxwell,
and you get the idea of these individual contributions
which get immortalized for all time, and that’s seductive.
It’s why many of us with the skillset
to go into maybe banking instead decided,
actually, there’s something about the idea
of being immortalized and contributing towards society
in a permanent way that is more attractive
than the financial reward of applying my skills elsewhere.
So, to some degree, that ego can be a benefit,
because it brings in skillful people into our field
who might otherwise be tempted by money elsewhere.
But, on the other hand, the closer you get
towards when you start flirting
with that Nobel Prize in your eyes,
or you think you’re on the verge of seeing something,
you can lose objectivity.
A very famous example of this is Barnard’s Star.
There was a planet claimed there by Peter van de Kamp,
I think it was in 1968, 69, and at the time,
it would have been the first ever exoplanet ever claimed.
And he felt assured that this planet was there.
He was actually using the wobbling star method,
but using the positions of the stars
to see them to claim this exoplanet.
It turned out that this planet was not there.
Subsequent analyses by both dynamicists and theorists
and those looking at the instrumental data
established fairly unanimously
that there was no way this planet was really there.
But Peter van de Kamp insisted it was there,
despite overwhelming evidence
that was accruing against him.
And even to the day he died,
which was I think in the early 90s,
he was still insisting this planet was there,
even when we were starting to make
the first genuine exoplanet discoveries.
And even at that point, I think Hubble
had even looked at that star
and had totally ruled out any possibility
of what he was talking about.
And so that’s a problem.
How do you get to a point as a scientist
where you just can’t accept
anything that comes otherwise?
Because it starts out with the dream of fame,
and then it ends in a stubborn refusal to ever back down.
Of course, the flip side of that
is sometimes you need that to have the strength
to carry a belief against the entire scientific community
that resists your beliefs.
And so it’s a double-edged sword.
That can happen, but I guess the distinction here
So in this case, the evidence was so overwhelming,
it wasn’t really a matter of interpretation.
It was, you had to collect,
you’d observe this star with the same star,
but with maybe 10, even 100 times greater precision
for prolonged, much longer periods of time.
And there was just no doubt at this point
this planet was a mirage.
And so that’s why you have to be very careful.
I always say, don’t ever name my wife and my daughter,
name this planet after me that you discover.
I’m like, I can’t ever name a planet after you
because I won’t be objective anymore.
How could I ever turn around to you
and say that planet wasn’t real that I named after you?
So you’re somebody that talks about,
and it’s clear in your eyes and in your way of being,
that you love the process of discovery,
that joy, the magic of just, you know,
seeing something, a new observation, a new idea, right?
But I guess the point is, when you have that great feeling,
is to then switch on the skepticism,
like to start testing, what does this actually mean?
Is this real?
What are the possible different interpretations
that could make this a lot less grand
than I first imagined?
So both have the wonder and the skepticism all in one brain.
Yeah, I think generally the more I want something to be true,
the more I inherently doubt it.
I grew up with a religious family
and was just sort of indoctrinated to some degree,
like many children are, that, okay, this is normal,
that there’s a God and this is the way the world is.
God created the Earth.
And then as I became more well-read and illiterate
of what was happening in the world scientifically,
I started to doubt.
And it really just struck me
that the hardest thing to let go of
when you do decide not to be religious anymore,
and it’s not really like a light bulb moment,
but it just kind of happens over sort of 11 to 13,
I think for me it was happening.
But it’s that sadness of letting go of this beautiful dream,
which you had in your mind of eternal life,
for behaving yourself on Earth,
you would have this beautiful heaven
that you could go to and live forever.
And that’s very attractive.
And for me personally,
that was one of the things that pulled me against it,
was this, it’s like, it’s too good to be true.
And it’s very convenient that this could be so.
And I have no evidence directly
in terms of a scientific sense to support this hypothesis.
And it just became really difficult
to reconcile my growth as a scientist.
And I know some people find that reconciliation.
I have not.
Maybe I will one day.
But as a general guiding principle,
which I think I obtained from that experience,
was that I have to be extremely guarded
about what I want to be true,
because it’s going to sway me to say things
which are not true if I’m not careful.
And that’s not what we’re trying to do as scientists.
So you felt from a religious perspective
that there was a little bit of a gravitational field
in terms of your opinions,
like it was affecting how you could be as a scientist.
Like as a scientific thinker, obviously, you were young.
Yeah, I think that’s true,
that whenever there’s something you want to be true,
it’s the ultimate seduction intellectually.
And I worry about this a lot with UFOs and with,
it’s true already with things like Venus,
phosphine and searching for astrobiological signals.
We have to guard against this all the way through
from however we’re looking for life,
however we’re looking for whatever this big question is.
There is a part of us,
I think I would love there to be life in the universe.
I hope there is life in the universe,
but I’m somewhat been on record several times
as being fairly firm about trying to remain consciously
agnostic about that question.
I don’t want to make up my mind about what the answer is
before I’ve collected evidence to inform that decision.
That’s how science should work.
If I already know what the answer is,
then what am I doing?
That’s not a scientific experiment anymore.
You’ve already decided, so what are you trying to learn?
What’s the point of doing the experiment
if you already know what the answer is?
There’s no point.
It’s so complicated because,
so if I’m being honest with myself,
when I imagine the universe,
so first thing I imagine about our world
is that we humans and me certainly
as one particular human know very,
my first assumption is I know almost nothing
about how anything works.
So first of all, that actually applies
for things that humans do know,
like quantum mechanics,
all the things that there’s different expertises
that I just have not dedicated to.
So even that’s starting point.
But if we take all of knowledge as human civilization,
we know almost nothing.
That’s kind of an assumption I have
because it seems like we keep discovering mysteries
and it seems like history,
human history is defined by moments when we said,
okay, we pretty much figured it all out
and then you realize a century later,
when you said that, you didn’t figure out anything.
Okay, so that’s like a starting point.
The second thing I have is I feel like
the entirety of the universe is just filled
with alien civilizations.
Statistically, there’s the important thing
that enables that belief for me
is that they don’t have to be human-like.
They can be anything.
And it’s just the fact that life exists
and just seeing the way life is on Earth,
that it just finds a way.
It finds a way in so many different complicated environments.
It finds a way.
Whatever that force is,
that same force has to find a way elsewhere also.
But then if I’m also being honest,
I don’t know how many hours in a day I spend
seriously considering the possibility that we’re alone.
I don’t know when my heart is in mind
or filled with wonder,
I think about all the different life that’s out there.
But to really imagine that we’re alone,
really imagine all the vastness that’s out there,
we’re alone, not even bacteria.
I would say you don’t have to believe that we are alone,
but you have to admit it’s a possibility
of our ignorance of the universe so far.
You can have a belief about something
in the absence of evidence.
And Carl Sagan famously described that
as the definition of faith.
If you believe something when there’s no evidence,
you have faith that there’s life in the universe.
But you can’t demonstrate,
you can’t prove it mathematically,
you can’t show me evidence of that.
Is there some, so mathematically, math is a funny thing,
is there, I mean, the way physicists think, like intuition,
so basic reasoning, is there some value to that?
Well, I’d say we’re always,
there’s certainly, you can certainly make
a very good argument,
I think you’ve kind of already made one,
just the vastness of the universe
is the default argument people often turn to,
that surely there should be others out there.
It’s hard to imagine.
There are of order of 10 to the 22 stars
in our observable universe.
And so, really the question comes down to
what is the probability of one of those
10 to the 22 planets, let’s say,
Earth-like planets, if they all have Earth-like planets,
going on to form life, spontaneously?
That’s the process of abiogenesis,
the spontaneous emergence of life.
Also, the word spontaneous is a funny one.
Well, okay, maybe we won’t use spontaneous,
but not being, let’s say,
seeded by, say, some other civilization
or something like that, it naturally emerges.
Because even the word spontaneous
makes it seem less likely.
Like there’s just this chemistry
and an extremely random process.
Right, it could be a very gradual process
over millions of years of growing complexity
in chemical networks.
Maybe there’s a force in the universe
that pushes it towards interesting complexity,
pockets of complexity,
that ultimately creates something like life
which we can’t possibly define yet.
And sometimes it manifests itself
into something that looks like humans.
But it could be a totally different
kind of computational information processing system
that we’re too dumb to even visualize.
Yeah, I mean, certainly,
I mean, it’s kind of weird
that complexity develops at all, right?
Because it seems like the opposite
to our physical intuition,
if you’re training in physics,
of entropy, that things should,
complexity’s hard to spontaneously,
or I shouldn’t say spontaneously,
but hard to emerge in general.
And so that’s an interesting problem.
I think there’s been,
certainly from an evolutionary perspective,
you do see growing complexity.
And there’s a nice argument,
I think it’s by Gould,
who shows that if you have
a certain amount of complexity,
it can either become less complex
or more complex through random mutation.
And the less complex things
are stripping away something,
something that was necessary,
potentially, to their survival.
And so in general,
that’s gonna be not particularly useful
in its survival.
And so it’s gonna be detrimental
to strip away a significant amount
of its useful traits.
Whereas if you add something,
the most typical thing that you add
is probably not useful at all.
It’s probably just,
doesn’t really affect its survival negatively,
but neither does it provide any significant benefit.
But sometimes, on rare occasions, of course,
it will be of benefit.
And so if you have a certain level of complexity,
it’s hard to go back in complexity,
but it’s fairly easy to go forward
with enough bites at the cherry.
You will eventually build up in complexity.
And that tends to be why we see complexity
grow in, certainly in an evolutionary sense,
but also perhaps it’s operating
in chemical networks
that led to the emergence of life.
I guess the real problem I have
with the numbers game,
just to come back to that,
is that we are talking about
a certain probability of that occurring.
It may be to go from the primordial soup,
however you want to call it,
the ingredients that the earth started with,
the organic molecules,
the probability of going from that initial condition
to something that was capable
of Darwinian natural selection
that maybe we could define as life,
the probability of that is maybe 1%,
1% of the time that happens,
in which case you’re right.
The universe will be absolutely teeming with life,
but it could also be 10 to the power of minus 10,
in which case it’s one per galaxy,
or 10 to the power of minus 100,
in which case the vast majority of universes even
do not have life within it.
You said 1%,
but it could be 90% if the conditions,
the chemical conditions of a planet are correct
or a moon are correct.
I admit that.
It could be any of those numbers.
And the challenge is we just have no rigorous reason
to expect why 90% is any,
because we’re talking about a probability for probability.
Is 90% more a priori likely
than 10 to the power of minus 20?
Well, the thing is,
we do have an observation, N of one, of Earth.
And it’s difficult to know what to do with that,
what kind of intuition you build on top of that,
because on Earth, it seems like life finds a way
in all kinds of conditions,
in all kinds of crazy conditions.
And it’s able to build up from the basic chemistry.
You could say, okay, maybe it takes a little bit of time
to develop some complicated technology,
like mitochondria, I don’t know, like photosynthesis.
Fine, but it seems to figure it out
and do it extremely well.
Yeah, but I would say you’re describing
a different process.
I mean, maybe I’m at fault
for separating these two processes,
but to me, you’re describing basically natural selection
evolution at that point.
Whereas I’m really describing abiogenesis,
which is, to me, a separate distinct process.
To you, limited to human scientists, yes,
but why would it be a separate process?
Why is the birth of life a separate process
from the process of life?
I mean, we’re uncomfortable with the Big Bang.
We’re uncomfortable with the first thing, I think.
Like, where does this come from?
Right, so I think I would say,
I just twist that question around and say,
you’re saying, why is it a different process?
And I would say, why shouldn’t it be a different process?
Which isn’t really a good defense,
except to say that we have knowledge
of how natural selection evolution works.
We think we understand that process.
We have almost no information about the earlier stages
of how life emerged on our planet.
It may be that you’re right,
and it is a part of a continuum.
It may be that it is also a distinct,
improbable set of circumstances
that led to the emergence of life.
As a scientist, I’m just trying to be open-minded
to both possibilities.
If I assert that life must be everywhere,
to me, you run the risk of experimenter’s bias.
If you think you know what the answer is,
if you look at an Earth-like planet,
and you are preconditioned to think
there’s a 90% chance of life on this planet,
it’s going to, at some level,
affect your interpretation of that data.
Whereas if I, however critical you might be
of the agnosticism that I impose upon myself,
remain open to both possibilities,
then I trust in myself to make a fair assessment
as to the reality of that evidence for life.
Yeah, but I wonder, sort of scientifically,
and that’s really beautiful to hear,
and inspiring to hear.
I wonder scientifically how many firsts we truly know of,
and then we don’t eventually explain
as actually a step number one million in a long process.
So I think that’s a really interesting thing
if there’s truly firsts in this universe.
For us, whatever happened at the Big Bang
is a kind of first, the origin of stuff.
Again, it seems like history shows
that we’ll figure out
that it’s actually a continuation of something.
But then physicists say that time is emergent,
and that our causality in time
is a very human kind of construct,
that it’s very possible that all of this,
so there could be really firsts
of a thing to which we attach a name.
So whatever we call life, maybe there is an origin of it.
Yeah, and I would also say,
I’m open to the idea of it being part of a continuation,
but the continuation maybe is more broader,
and it’s a continuation of chemical systems
and chemical networks.
And what we call this one particular type of chemistry
in this behavior of chemistry life,
but it is just one manifestation
of all the trillions of possible permutations
in which chemical reactions can occur.
And we assert specialness to it,
because that’s what we are.
And so it’s also true of intelligence.
You could extend the same thing
and say we’re looking for intelligent life in the universe,
and then you sort of, where do you define intelligence?
Where’s that continuum of something
that’s really like us, are we alone?
There may be a continuum of chemical systems,
a continuum of intelligences out there,
and we have to be careful of our own arrogance
of assuming specialness about what we are,
that we are some distinct category of phenomena,
whereas the universe doesn’t really care
about what category we are.
It’s just doing what it’s doing
and doing everything in infinite diversity
and infinite combinations is essentially what it’s doing.
And so we are taking this one slice and saying,
no, this has to be treated separately.
And I’m open to the idea
that it could be a truly separate phenomenon,
but it may just be like a snowflake.
Every snowflake’s different.
It may just be that this one particular,
iteration is another variant of the vast continuum.
And maybe the algorithm of natural selection itself
is an invention of earth.
I kind of also tend to suspect that this,
whatever the algorithm is,
it kind of operates at all levels throughout the universe.
But maybe this is a very kind of peculiar thing
that where there’s a bunch of chemical systems
that compete against each other,
somehow for survival under limited resources.
And that’s a very earth-like thing.
We have a nice balance of,
there’s a large number of resources,
enough to have a bunch of different kinds
of systems competing,
but not so many that they get lazy.
And maybe that’s why bacteria
were very lazy for a long time.
Maybe they didn’t have much competition.
I mean, I tried to,
as fun as it is to get into the speculation
about the definitions of life
and what life does
and this gross network of possibilities.
Honestly, for me,
the strongest argument for remaining agnostic
is to avoid that bias in assessing data.
I mean, we’ve seen it.
I mean, Percival Lowell,
I talked about on my channel maybe last year
or two years ago,
he’s a very famous astronomer who in the 19th century
was claiming the evidence of canals on Mars.
And from him, from his perspective,
and even at the time, culturally,
it was widely accepted that Mars would,
of course, have life.
I mean, I think it seems silly to us,
but it was kind of similar arguments
to what we’re using now about exoplanets,
that, well, of course there must be life in the universe.
How could it just be here?
And so it seemed obvious to people
that when you looked at Mars with its polar caps,
even its atmosphere, had seasons,
it seemed obvious to them
that that too would be a place
where life not only was present,
but had emerged to a civilization,
which actually was fairly comparable
in technology to our own,
because it was building canal systems.
Of course, a canal system
seems a bizarre technosignature to us,
but it was a product of their time.
To them, that was the cutting edge in technology.
It should be a warning shot, actually,
a little bit for us,
that if we think solar panels or building star links
or whatever, space mining
is like an inevitable technosignature,
that may be laughably antiquated
compared to what other civilizations
far more advanced than us may be doing.
And so anyway, Percival Lowell,
he, I think, was a product of his time
that he thought life was there.
Inevitably, he even wrote about it extensively.
And so when he saw these lines,
these lineae on the surface of Mars,
to him, it was just obvious they were canals.
And that was experimenters’ bias playing out.
He was told, for one,
that he had basically the greatest eyesight
out of any of his peers.
An ophthalmologist had told him that in Boston,
that his eyesight was absolutely spectacular.
So he just was convinced everything he saw was real.
And secondly, he was convinced there was life there.
And so to him, it just added up.
And then that kind of wasted decades of research,
of treating the idea of Mars being inhabited
by this canal civilization.
But on the other hand, it’s maybe not a waste
because it is a lesson in history
of how we should be always on guard
against our own preconceptions and biases
about whether life is out there.
And furthermore, what types of things life might do
if it is there.
If I were running this simulation,
which we’ll also talk about
because you make the case against it,
but if I were running a simulation,
I would definitely put you in a room with an alien
and just to see you mentally freak out for hours at a time.
Oh, that’d be great.
You for sure would have thought
you will be convinced that you’ve lost your mind.
I mean, no, not that.
But I mean, if we discover life,
we discover interesting new physical phenomena,
I think the right approach is definitely
to be extremely skeptical and be very, very careful
about things you want to be true.
That’s really admirable.
I’m not some extreme denialist of evidence.
If there was compelling evidence
for life on another planet,
I would be the first one to be celebrating that
and be shaking hands with the alien
on the White House lawn or whatever.
I grew up with Star Trek and that was my fantasy
was to be Captain Kirk
and fly across the stars meeting other civilizations.
So there’s nothing more I’d want to be true as I’ve said,
but we just have to guard against it
when we’re assessing data.
But I have to say I’m very skeptical
that we will ever have that Star Trek moment.
Even if there are other civilizations out there,
they’re never gonna be at a point
which is in technological lockstep with us,
similar level of development,
even intellectually the idea
that they could have a conversation with us
even through a translator.
I mean, we can’t communicate with humpback whales.
We can’t communicate with dolphins in a meaningful way.
We can sort of bark orders at them,
but we can’t have abstract conversations
with them about things.
And so the idea that we will ever have
that fulfilling conversation, I’m deeply skeptical of.
And I think a lot of us are drawn to that.
I think it is maybe a replacement for God to some degree,
that Father figure civilization that might step in,
teach us the air of our ways
and bestow wisdom upon our civilization.
But they could equally be a giant fungus
that doesn’t even understand the idea of socialization
because it’s the only entity on its planet.
It just swells over the entire surface.
And it’s incredibly intelligent
because maybe each node communicates with each other
to create essentially a giant neural net.
But it has no sense of what communication even is.
And so alien life is out there,
surely can be extremely diverse.
I’m pretty skeptical that we’ll ever get
that fantasy moment I always had as a kid
of having a dialogue within the civilization.
So dialogue, yes.
What about noticing them?
What about noticing signals?
Do you hope…
So one thing we’ve been talking about
is getting signatures, biosignatures,
technosignatures about other planets.
Maybe if we’re extremely lucky in our lifetime
to be able to meet life forms,
get evidence of living or dead life forms on Mars
or the moons of Jupiter and Saturn.
What about getting signals from outer space,
What would those signals potentially look like?
That’s a hard question to answer
because we are essentially engaging in xenopsychology
to some degree.
What are the activities of another civilization?
A lot of that is inevitable.
What does the word xenopsychology,
I apologize to interrupt, mean?
Maybe I’m just fabricating that word, really,
but trying to guess at the machinations
and motivations of another intelligent being
that was completely evolutionary divorced from us.
So it’s like you said, exo-moons,
it’s exopsychology, extrasolar psychology.
Yeah, alien psychology is another way
of maybe making it more grounded.
But we can’t really guess at their motivations too well,
but we can look at the sorts of behaviors we engage in
and at least look for them.
We’re always guilty that when we look for biosignatures,
we’re really looking for,
and even when we look for planets,
we’re looking for templates of Earth.
When we look for biosignatures,
we’re looking for templates of Earth-based life.
When we look for tetanus signatures,
we tend to be looking for templates of our own behaviors
or extrapolations of our behaviors.
So there’s a very long list of tetanus signatures
that people have suggested we could look for.
The earliest ones were, of course, radio beacons.
That was sort of Project Osma
that Frank Drake was involved in,
trying to look for radio signatures,
which could either be just like blurting out
high-power radio signals saying, hey, we’re here,
or could even have encoded within them
galactic encyclopedias for us to unlock,
which has always been the allure of the radio technique.
But there could also be unintentional signatures.
For example, you could have something
like the satellite system that we’ve produced
around the Earth, the artificial satellite system,
Starlink-type systems we mentioned.
You could detect the glint of light across those satellites
as they orbit around the planet.
You could detect a geostationary satellite belt,
which would block out some light
as the planet transited across the star.
You could detect solar panels,
potentially spectrally, on the surface of the planet.
Heat island effects.
New York is hotter than New York State
by a couple of degrees
because of the heat island effect of the city.
And so you could thermally map different planets
and detect these.
So there’s a large array of things that we do
that we can go out and hypothesize we could look for.
And then on the furthest end of the scale,
you have things which go far beyond our capabilities,
such as warp drive signatures, which have been proposed.
You get these bright flashes of light
or even gravitational wave detections
from LIGO could be detected.
You could have Dyson spheres.
The idea of covering, basically,
a star’s completely covered by some kind of structure
which collects all the light from the star
to power the civilization.
And that would be pretty easily detectable to some degree
because you’re transferring all of the visible light.
Thermodynamically, it has to be re-emitted
so it would come out as infrared light.
So you’d have an incredibly bright infrared star,
yet one that was visibly not present at all.
And so that would be a pretty intriguing
signature to look for.
Well, is there efforts to look for something like that
for Dyson spheres out there
for the strong infrared signal?
There has been.
Yeah, there has been.
And there’s been, I think in the literature,
there was one with the IRAS satellite,
which is an infrared satellite.
They targeted, I think, of order of 100,000 stars,
and found no convincing examples
of what looked like a Dyson sphere star.
And then Jason Wright and his team extended this,
I think, using WISE,
which is another infrared satellite,
to look around galaxies.
So could an entire galaxy have been converted
into Dyson spheres,
or a significant fraction of the galaxy?
Which is basically the Kardashev Type III, right?
This is when you’ve basically mastered
the entire galactic pool of resources.
And again, out of 100,000 nearby galaxies,
there appears to be no compelling examples
of what looks like a Dyson galaxy,
if you want to call it that.
So that by no means proves that they don’t exist
or don’t happen,
but it seems like it’s an unusual behavior
for a civilization to get to that stage of development
and start harvesting the entire stellar output.
And I mean, LIGO is super interesting
with gravitational waves.
If that kind of experiment could start seeing some weirdness,
some weird signals that compare
to the power of cosmic phenomena.
I mean, it’s a whole new window to the universe,
not just in terms of astrophysics,
but potentially for technosignatures as well.
I have to say, with the warp drives,
I am skeptical that warp drives are possible
because you have kind of a fundamental problem in relativity.
You can either really have relativity,
faster than light travel, or causality.
You can only choose two of those three things.
You really can’t have all three in a coherent universe.
If you have all three,
you basically end up with the possibility
of these kind of temporal paradoxes
and time loops and grandfather paradoxes.
Well, can’t there be pockets of causality?
Something like that?
Like where there’s like pockets of consistent causality.
You could design it in that way.
You could be, you know,
if you had a warp drive or a time machine,
essentially you could be, you know,
you could be very conscious
and careful of the way you use it
so as to not to cause paradoxes
or just do it in a local area or something.
But the real fundamental problem is
you always have the ability to do it.
And so in a vast cosmic universe,
if time machines were all over the place,
there’s too much risk of someone doing it, right?
Of somebody having the option
of essentially breaking the universe with this.
So this is a fundamental problem.
Hawking has this chronology protection conjecture
where he said that essentially this just can’t be allowed
because it breaks all our laws of physics
if time travel is possible.
Current laws of physics, yes.
And so we need to rip up relativity.
I mean, that’s the point is the current laws of physics.
So you’d have to rip up our current law of relativity
to make sense of how FTL could live in that universe
because you can’t have relativity, FTL and causality
sit nicely and play nicely together.
But we currently don’t have quantum mechanics
and relativity playing nice together anyway.
So it’s not like everything is all a nice little fabric.
It’s certainly not the full picture.
There must be more to go.
So it’s already ripped up,
so might as well rip it up a little more.
And in the process, actually try to connect the two things.
Because maybe in the unification of the standard model
and general relativity, maybe there lies
some kind of new wisdom about warp drives.
So by the way, warp drives is somehow messing
with the fabric of the universe
to be able to travel faster than the speed of light?
Yeah, you’re basically bending space-time.
You could also do it with a wormhole or a tachy.
Some of the hypothetical FTLs,
this doesn’t have to necessarily be the Alcubierre drive,
the warp drive.
It could be any faster than light system.
As long as it travels superluminally,
it will violate causality.
And presumably that will be observable with LIGO.
Potentially, yeah, potentially.
Depends on, I think, the properties
of whatever the spacecraft is.
I mean, one problem with warp drives is,
there’s all sorts of problems with warp drives.
But when it-
Like the start of that sentence,
one problem, the warp drive.
There’s just this one minor problem
that we have to get around.
But when it arrives at its destination,
it basically collects this vast,
basically has like an event horizon
almost at the front of it.
And so it collects all this radiation
at the front as it goes.
And when it arrives,
all that radiation gets dumped on its destination,
would basically completely exterminate
the planet it arrives at.
That radiation is also incident within the shell itself.
There’s Hawking radiation occurring within the shell,
which is pretty dangerous.
And then it also has,
it raises all sorts of exacerbations
of the Fermi paradox, of course, as well.
So you might be able to explain
why we don’t see a galactic empire.
I mean, even here it’s hard.
You might be able to explain
why we don’t see a galactic empire
if everybody’s limited to Voyager 2 rocket speeds
of like 20 kilometers per second or something.
But it’s a lot harder to explain
why we don’t see the stars populated by galactic empires
when warp drive is eminently possible
because it makes expansion so much more trivial
that it makes our life harder.
There’s some wonderful simulation work
being done out of Rochester
where they actually simulate all the stars in the galaxy
or a fraction of them.
And they spawn a civilization in one of them
and they let it spread out at sub-light speeds.
And actually the very mixing of the stars themselves,
because the stars are not static,
they’re in orbit of the galactic center
and they have crossing paths with each other.
If you just have a range of even like five light years
and your speed is of order of a few percent,
the speed of light is the maximum you can muster,
you can populate the entire galaxy
within something like 100,000,
about a million years or so.
So a fraction of the lifetime of the galaxy itself.
And so this raises some fairly serious problems
because if any civilization in the entire history
of the galaxy decided to do that,
then either we shouldn’t be here
or we happen to live in this kind of rare pocket
where they chose not to populate to.
And so this is sometimes called fact A, Hart’s fact A.
As the fact A is that a civilization is not here now,
an alien civilization is not in present occupation
of the Earth.
And that’s difficult to resolve with the apparent ease
at which even a small extrapolation of our own technology
could potentially populate a galaxy
in far faster than galactic history.
So to me, by the way,
the Fermi paradox is truly a paradox for me.
But I suspect that if aliens visit Earth,
I suspect if they are everywhere,
I think they’re already here and we’re too dumb to see it.
But leaving that aside,
I think we should be able to, in that case,
have very strong, obvious signals
when we look up at the stars,
at the emanation of energy required.
We would see some weirdness
that like where these are these kinds of stars
and these are these kinds of stars
that are being messed with,
like leveraging the nuclear fusion of stars
to do something useful.
The fact that we don’t really see that,
like maybe you can correct me,
wouldn’t we be able to,
if there is like alien civilizations running galaxies,
wouldn’t we see weirdnesses from an astronomy perspective
with the way the stars are behaving?
Yeah, I mean, it depends exactly what they’re doing.
But I mean, the Dyson Sphere example is one
that we already discussed
where a survey of 100,000 nearby galaxies
find that they have all been transformed
into Dyson Sphere collectors.
You could also imagine them doing things like,
we wrote a paper about this recently, of star lifting,
where you can extend the life of your star
by scooping mass off the star.
So you’d be doing stellar engineering, essentially.
Space, if you’re doing a huge amount of asteroid mining,
you would have a spectral signature
because you’re basically filling the solar system with dust
by doing that.
There’d be debris from that activity.
And so there are some limits on this.
Certainly we don’t see bright flashes,
which would be,
one of these consequences of warp drives, as I said,
is as they decelerate,
they produce these bright flashes of light.
We don’t seem to see evidence of those kinds of things.
We don’t see anything obvious around the nearby stars
or the stars that we’ve surveyed in detail beyond that
that indicate any kind of artificial civilization.
The closest maybe we had was Boyajian star
that there was a lot of interest in.
There was a star that was just very peculiarly
dipping in and out its brightness.
And it was hypothesized for a time
that that may indeed be some kind of Dyson-like structure.
So maybe a Dyson sphere that’s half built.
And so as it comes in and out,
it’s blocking out huge swaths of the star.
It was very difficult to explain it
really with any kind of planet model at the time.
But an easier hypothesis that was proposed
was it could just be a large number of comets
or dust or something,
or maybe a planet that had broken apart.
And as its fragments orbit around,
it blocks out starlight.
And it turned out with subsequent observations of that star,
which especially the amateur astronomy community
made a big contribution to as well,
that the dips were chromatic,
which was a real important clue
that that probably wasn’t a solid structure then
that was going around it.
It was more likely to be dust.
Dust is chromatic.
By chromatic, I mean it looks different in different colors.
So it blocks out more red light than blue light.
If it was a solid structure, it shouldn’t do that.
It should be opaque, right?
A solid metal structure or something.
So that was one of the clear indications.
And the behavior of, and the way the light changed
or the dips changed across wavelength
was fully consistent with the expectations
of what small particulates would do.
And so that’s very hard.
I mean, the real problem with alien hunting,
the real problem-
The technical term.
This is the real-
The one problem.
The one problem with the warp drive
and the one problem with the alien hunting, yes.
But well, actually I’d say there’s three big problems for me
with any search for life,
which includes UFOs or the way to fossils on Mars,
is that aliens have three unique properties as a hypothesis.
One is they have essentially
unbounded explanatory capability.
So there’s almost no phenomena I can show you
that you couldn’t explain with aliens to some degree.
You could say, well, the aliens just have
some super high-tech way of creating that illusion.
The second one would be unbounded avoidance capacity.
So I might see a UFO tomorrow,
and then the next day, and then the next day,
and then predict I should see it on Thursday
at the end of the week, but then I don’t see it.
But I could always get out of that and say,
well, that’s just because they chose not to come here.
You know, they have this-
They can always avoid future observations fairly easily.
If you survey an exoplanet for biosignatures
and you don’t see oxygen, you don’t see methane,
that doesn’t mean there’s no one living there.
They could always be either tricking their atmosphere,
engineering it, we actually wrote a paper about that,
how you can use lasers to hide your biosignatures
as advanced civilization.
Or you could just be living underground
or underwater or something where there’s no biosignatures.
So you can never really disprove there’s life
on another planet or on another star.
It has infinite avoidance.
And then finally, the third one is that we have
incomplete physical understanding of the universe.
So if I see a new phenomena,
which Boyajian’s star was a good example of that,
we saw this new phenomena of these strange dips
we’d never seen before.
It was hypothesized immediately this could be aliens.
It’s like a god of the gaps,
but it turned out to be incomplete physical understanding.
And so that happens all the time.
In the first pulsar that was discovered, same story.
Jocelyn Bell kind of somewhat tongue-in-cheek
called it Little Green Man 1
because it looked a lot like the radio signature
that was expected from an alien civilization.
But of course, it turned out to be
a completely new type of star that we had never seen before,
which was a neutron star with these two jets
coming out the top of it.
And so that’s a challenge.
Those three things are really, really difficult
in terms of experimental design
for a scientist to work around.
Something that can explain anything, can avoid anything,
so it’s almost unfalsifiable,
and could always just be, to some degree, as you said,
we have this very limited knowledge
of the infinite possibilities of physical law,
and we’re probably only scratching the surface.
Each time, and we’ve seen it so often in history,
we may just be detecting some new phenomena.
Well, that last one, I think I’m a little more okay
with making mistakes on.
Yeah, because it’s exciting still.
Because no matter, so you might exaggerate
the importance of the discovery,
but the whole point is to try to find stuff
in this world that’s weird,
and try to characterize that weirdness.
Sure, you can throw a little green man as a label on it,
but eventually, it’s as mysterious and as beautiful,
as interesting as a little green man.
Like, we tend to think that there’s some kind of threshold,
but there’s all kinds of weird organisms on this Earth
that operate very differently than humans
that are super interesting.
The human mind is super interesting.
I mean, weirdness and complexity is as interesting
in any of its forms as what we might think from Hollywood
what aliens are.
So that’s okay.
Looking for weirdnesses on Mars.
That’s one of the best sales pitches
to do technosignature work,
is that we always have that as our fallback,
that we’re gonna look for alien signatures.
If we fail, we’re gonna discover
some awesome new physics along the way.
And so, any kind of signature that we detect
is always going to be interesting.
And so, that compels us to have not only the question
of looking for life in the universe,
but it gives us a strong scientific grounding
as to why this sort of research should be funded
and should be executed,
because it always pushes the frontiers of knowledge.
I wonder if we’ll be able to discover
and be open enough to a broad definition of aliens,
where we see some kind of technosignature,
basically like a Turing test,
like this thing is intelligent.
Like it’s processing information in a very interesting way.
But you could say that about chemistry.
You could say that about physics.
Maybe not physics, chemistry.
Like interesting, complex chemistry,
you could say that this is processing.
This is storing information.
This is propagating information over time.
So, I mean, it’s a gray area
between a living organism that we would call an alien,
and a thing that’s super interesting
and is able to carry some kind of intelligence.
Yeah, information is a really useful way
to frame what we’re looking for, though,
because then you’re divorced from making assumptions
about even a civilization, necessarily,
or anything like that.
So, any kind of information-rich signature,
indeed, you can take things like the light curve
from Boyajian’s star and ask,
what is the minimum number of free parameters
the minimum information content
that must be encoded within this light curve?
And the hope is that maybe from,
a good example would be from a radio signature.
You detect something that has 1,000 megabytes
of parameters, essentially, contained within it.
That’s pretty clearly, at that point,
not the product of a natural process,
or it’s any natural process that we could possibly imagine
with our current understanding of the universe.
And so, thinking that even if we can’t decode,
which, actually, I’m skeptical we’d be able
to ever decode it in our lifetimes.
It would probably take decades to fully ever figure out
what they’re trying to tell us.
But if there was a message there,
we could at least know
that there is high information content,
and there is complexity,
and that this is a attempt at communication
and information transfer,
and leave it to our subsequent generations
to figure out what exactly it is they’re trying to say.
What, again, a wild question,
and thank you for…
I really, really appreciate that.
But what kind of signal in our lifetime,
what kind of thing do you think might happen,
could possibly happen,
where the scientific community would be convinced
that there’s alien civilizations out there?
Like what, so you already said,
maybe a strong infrared signature
for something like a Dyson sphere.
Yeah, that’s possible,
but that’s also to some degree a little bit ambiguous,
That’s the challenge, sorry to interrupt,
is where your brain would be,
like you as a scientist,
would be like, I know it’s ambiguous,
but this is really weird.
I think if you had some,
I can imagine something like a prime number sequence,
or a mathematical sequence,
like the Fibonacci series,
something being broadcasted.
Mathematically provable that this is not
a physical phenomenon.
Right, I mean, yeah,
prime numbers is a pretty good case,
because there’s no natural phenomena
that produces prime number sequences.
It seems to be a purely an abstract mathematical concept,
as far as I’m aware.
And so if we detected a series of radio blips
that were following that sequence,
it would be pretty clear to me,
or it could even be Carl Sagan suggested
that pi could be encoded in that,
or you might use the hydrogen line,
but multiply it by pi,
like some very specific frequency of the universe,
like a hydrogen line,
but multiply it by a abstract mathematical constant
that would imply strongly
that there was someone behind the scenes operating that.
Sorry, stored in which phenomena, though?
In that case, I think of a radio wave.
But the information, I mean,
we kind of toyed with this idea
in a video I did about hypothetical civilization
on my channel.
But one kind of fun way,
I do want to bring this conversation
towards time a little bit,
and thinking about not just looking
for life and intelligence around us right now,
but looking into the past and even into the future
to some degree, or communicating with the future.
And so we had this fun experiment
of imagining a civilization that was born
at the beginning of the history of the galaxy
and being the first and what it would be like for them.
And they were desperately searching for evidence of life,
but couldn’t find it.
And so they decided to try and leave something behind
for future civilizations to discover,
to tell them about themselves.
But of course, a radio scene’s just not gonna work there
because it has to have a power source,
and that’s a piece of machinery.
It’s gonna eventually break down.
It’s gonna be hard to maintain that
for billions of years timescale.
And so you wanted something that was kind of passive,
that doesn’t require an energy source,
but can somehow transmit information,
which is hard to think about something
that satisfies those criteria.
But there was a proposal
by one of my colleagues, Luke Arnold,
which inspired a lot of us in Technosignatures.
And he suggested that you could build artificial transitors.
So you could build sheets of material
that transit in front of the star.
Maybe one thin sheet passes across first,
then two, then three, then five, then seven,
so you could follow the prime number sequence of these.
And so there’d be a clear indication
that someone had manufactured those,
but they don’t require any energy source
because they’re just sheets of material in orbit of the star.
They would eventually degrade from micrometeorites,
and maybe they always would become destabilized,
but they should have lifetimes far exceeding
the lifetime of any battery or mechanical electronic system
that we could, at least with our technology,
conceive of building.
And so you could imagine then extending that,
and how could you encode not just a prime number sequence,
but maybe in the spatial pattern
of this very complex light curve we see,
you could encode more and more information
through 2D shapes and the way those occultations happen.
And maybe you could even encode messages
and in-depth information from that.
You could even imagine it being
like a lower layer of information,
which is just the prime number sequence,
but then you look closely and you see
the smaller divots embedded within those
that have a deeper layer of information to extract.
And so to me, something like that
would be pretty compelling,
that there was somebody who had,
unless it’s just a very impressive hoax,
that would be a pretty compelling evidence
for this civilization.
And actually, the methods of astronomy right now
are kind of marching towards being able
to better and better detect a signal like that.
Yeah, I mean, to some degree,
it’s just building bigger aperture in space.
The bigger the telescope,
the finer ability to detect those minute signals.
Do you think the current sort of the scientific community,
another weird question,
but just the observations that are happening now,
do you think they’re ready for a prime number sequence?
In the sort of, if we’re using the current method,
the transit timing variation method,
like do you think you’re ready?
Do you have the tools to detect the prime number sequence?
Yeah, for sure.
I mean, there’s 200,000 stars that Kepler monitored
and it monitored them all the time.
It took a photo of each one of them every 30 minutes,
measured their brightness,
and it did that for four and a half years.
And so you have already,
and Tess is doing it right now, another mission.
And so you have already an existing catalog
and people are genuinely scouring
through each of those light curves
with automated machine learning techniques.
We even developed some in our own team
that can look for weird behavior.
We wrote a code called the weird detector, for instance.
You know, it was just the most generic thing possible.
Don’t assume anything about the signal shape.
Just look for anything that repeats.
The signal shape can be anything
and we kind of learn the template of the signal
from the data itself.
And then it’s like a template matching filter
to see if that repeats many, many times in the data.
And so we actually applied that
and found a bunch of interesting stuff,
but we didn’t see anything
that was the prime number sequence,
at least on the Kepler data.
That’s 200,000 stars, which sounds like a lot,
but compared to 200 billion stars in the Milky Way,
it’s really just scratching the surface.
So one, because there could be something
much more generalizable than the prime number sequence,
it’s ultimately the question of a signal
that’s very difficult to compress
in the general sense of what compress means.
So maybe as we get better and better
in machine learning methods
that automatically figure out, analyze the data
to understand how to compress it,
you’ll be able to discover data
that for some reason is not compressible.
But then, you know, compression really is a bottomless pit
because that’s really what intelligence is,
is being able to compress information.
Yeah, and to some degree, the more you,
I would imagine, I don’t work in compression algorithms,
but I would imagine the more you compress your signal,
the more assumptions that kind of go
on behalf of the decoder,
the more skilled they really have to be.
You know, a prime number sequence
is completely unencoded information, essentially.
But if you look at the Arecibo message,
they were fairly careful with their pixelation
of this simple image they sent
to try and make it as interpretable as possible
to be that even a dumb alien would be able to figure out
what we’re trying to show them here
because there’s all sorts of conventions
and rules that are built in
that we tend to presume when we design our messages.
And so if your message is assuming
they know how to do an MP3 decoder,
a particular compression algorithm,
I’m sure they could eventually reverse engineer it
and figure it out,
but you’re making it harder for them to get to that point.
So maybe, I always think, you know,
you probably would have a two-tier system, right?
You’d probably have some lower-tier key system,
and then maybe beneath that,
you’d have a deeper compressed layer
of more in-depth information.
What about maybe observing actual physical objects?
So first, let me go to your tweet
as a source of inspiration.
You tweeted that it’s interesting to ponder
that if Oort clouds are ever mined
by the systems of alien civilizations,
mining equipment from billions of years ago
could be in our Oort cloud
since the Oort clouds extend really, really, really,
really far outside the actual star.
So, you know, mining equipment,
just basic, boring mining equipment out there.
I don’t know if there’s something interesting to say
about Oort clouds themselves that are interesting to you
and about possible non-shiny light-emitting mining equipment
from alien civilizations.
Yeah, I mean, that’s kind of the beauty
of the field of technosignatures and looking for life
is you can find inspiration and intellectual joy
in just the smallest little thing
that starts a whole thread of building upon it
and wondering about the implications.
And so in this case, I was just really struck by,
we kind of mentioned this a little bit earlier,
the idea that stars are not static.
We tend to think of the galaxy as having stars
in a certain location from the center of the galaxy
and they kind of live there.
But in truth, the stars are not only orbiting
around the center of the galaxy,
but those orbits are themselves changing
over time, they’re processing.
And so in fact, the orbits look more like a spirograph
if you’ve ever done those as a kid,
they kind of whirl around and trace out
all sorts of strange patterns.
And so the stars intersect with one another.
And so the current closest star to us is Proxima Centauri,
which is about 4.2 light years away.
But it will not always be the closest star
and over millions of years,
it will be supplanted by other stars.
In fact, stars that will come even closer than Proxima
within just a couple of light years.
And that’s been happening, not just we can project
that will happen over the next few million years,
but that’s been happening presumably
throughout the entire history of the galaxy
for billions of years.
And so if you went back in time,
there would have been all sorts of different nearest stars
at different stages of the Earth’s history.
And those stars are so close that their Oort clouds
do intermix with one another.
So the Oort cloud can extend out to even a light year
or two around the Earth.
There’s some debate about exactly where it ends.
It probably doesn’t really have a definitive end,
but kind of more just kind of peters out
more and more and more as you go further away.
By the way, for people who don’t know an Oort cloud,
I don’t know what the technical definition is,
but a bunch of rocks that kind of, no,
objects that orbit the star.
And they can extend really, really, really far
because of gravity.
These are objects that probably are mostly icy rich.
They were probably formed fairly similar distances
to Jupiter and Saturn, but were scattered out
through the interactions of those giant planets.
We see a circular disk of objects around us,
which kind of looks like the asteroid belt,
but just further away called the Kuiper belt.
And then further beyond that,
you get the Oort cloud.
And the Oort cloud is not on a disk.
It’s just a sphere.
It kind of surrounds us in all directions.
So these are objects that were scattered out
through three-dimensionally in all different directions.
And so those objects are potentially resources for us,
especially if you were planning
to do an interstellar mission one day,
you might want to mine the water
that’s embedded within those and use that
as either oxygen or fuel for your rocket.
And so it’s quite possible.
There’s also some rare earth metals
and things like that as well,
but it’s quite possible that a civilization
might use Oort cloud objects as a jumping off point.
Or in the Kuiper belt,
you have things like planet nine even.
There might even be objects beyond in the Oort cloud,
which are actually planet-like that we just cannot detect.
These objects are very, very faint.
So that’s why they’re so hard to see.
I mean, even planet nine, it’s hypothesized to exist,
but we’ve not been able to confirm its existence
because it’s at something like a thousand AU away from us,
a thousand times the distance of the earth from the sun.
And so even though it’s probably larger than the earth,
the amount of light it reflects from the sun,
the sun just looks like a star at that point,
so far away from it that it barely reflects anything back.
It’s extremely difficult to detect.
So there’s all sorts of wonders
that may be lurking out in the outer solar system.
And so this leads you to wonder,
you know, in the Oort cloud,
that Oort cloud must have intermixed
with other Oort clouds in the past.
And so what fraction of the Oort cloud truly belongs to us,
belongs to what was scattered from Jupiter and Saturn,
what fraction of it could in fact be interstellar visitors?
And of course, we’ve got excited about this recently
because of Oumuamua, this interstellar asteroid,
which seemed to be at the time
the first evidence of an interstellar object.
But when you think about the Oort cloud intermixing,
it may be that a large fraction of comets,
comets are seeded from the Oort cloud
that eventually come in.
Some of those comets may indeed
have been interstellar in the first place
that we just didn’t know about through this process.
There even is an example, I can’t remember the name,
there’s an example of a comet
that has a very peculiar spectral signature
that has been hypothesized
to have actually been an interstellar visitor,
but one that was essentially sourced
through this Oort cloud mixing.
And so this is kind of intriguing.
And also, the outer solar system is just such a,
it’s like the bottom of the ocean.
We know so little about what’s on the bottom
of our own planet’s ocean,
and we know next to nothing
about what’s on the outskirts of our own solar system.
It’s all darkness.
So like, that’s one of the things
is to understand the phenomenon, we need light.
And we need to see how light interacts with it
or what light emanates from it.
But most of our universe is darkness.
So it’s, there could be a lot of interesting stuff.
I mean, this is where your interest is
with the cool worlds and the interesting stuff
lurks in the darkness, right?
Basically all of us, you know, 400 years of astronomy,
our only window into the universe has been light.
And that has only changed quite recently
with the discovery of gravitational waves.
That’s now a new window.
And hopefully, well, to some degree, I guess,
solar neutrinos we’ve been detecting for a while,
but they come from the sun, not interstellar space.
But we may be able to soon detect neutrino messages
has even been hypothesized as a way of communicating
between civilizations as well,
or just do neutrino telescopes to study the universe.
And so there’s a growing interest
in what we’d call multi-messenger astronomy now.
So not just messages from light,
but messages from these other physical packets
of information that are coming our way.
But when it comes to the outer solar system,
light really is our only window.
There’s two ways of doing that.
One is you detect the light from the Oort cloud object
itself, which as I just said, is very, very difficult.
There’s another trick,
which we do in the Kuiper belt especially,
and that’s called an occultation.
And so sometimes those objects will just pass in front
of a distant star, just coincidentally.
These are very, very brief moments.
They last for less than a second.
And so you have to have a very fast camera to detect them,
which conventionally astronomers
don’t usually build fast cameras.
Most of the phenomena we observe occurs on hours,
minutes, days even.
But now we’re developing cameras which can take,
you know, thousands of images per second,
and yet do it at the kind of astronomical fidelity
that we need for this kind of precise measurement.
And so you can see these very fast dips.
You even get these kind of diffraction patterns
that come around, which are really cool to look at.
And that’s, I kind of love it
because it’s almost like passive radar.
You have these pinpricks of light.
Imagine that you live in a giant black sphere,
but there’s these little pinholes that have been poked.
And through those pinholes,
almost laser light is shining through.
And inside this black sphere,
there are unknown things wandering around,
drifting around that we are trying to discover.
And sometimes they will pass in front of those
little pencil-thin laser beams, block something out.
And so we can tell that it’s there.
And it’s not an active radar
because we didn’t actually beam anything out
and get a reflection off,
which is what the sun does.
The sun’s light comes off and it comes back.
That’s more like an active radar system.
There’s more like a passive radar system
where we are just listening very intently.
And so I’m kind of so fascinated by that,
the idea that we could map out the rich architecture
of the outer solar system just by doing something
that we could have done potentially for a long time ago,
which is just listening in the right way,
just tuning our instrumentation
to the correct way of not listening,
but viewing the universe to catch those objects.
Yeah, I mean, it’s really fascinating.
It seems almost obvious that your efforts,
when projected out in over like 100, 200 years,
will have a really good map,
through even methods like basically transit timing,
high-resolution transit timing,
but basically the planetary
and the planet satellite movements
of all the different star systems out there.
Yeah, and it could revolutionize
the way we think about the solar system.
I mean, that revolution has happened several times
in the past when we discovered Vesta in the 19th century.
That was, I think, the seventh planet for a while
or the eighth planet when it was first discovered.
And then we discovered Ceres
and there was a bunch of asteroid objects, Janus.
And so for a while, the textbooks had,
there was something like 13 planets in the solar system.
And then that was just a new capability
that was emerging to detect those small objects.
And then we ripped that up and said,
no, no, we’re gonna change the definition of a planet.
And then the same thing happened
when we started looking at the outer skirts
of the solar system.
Again, we found Eris, we found Sedna,
these objects which resembled Pluto.
And the more and more of them we found, make, make.
And eventually we, again, had to rethink
the way we even contextualize what a planet is
and what the nature of the outer solar system is.
So regardless as to what you think about the debate
about whether Pluto should be devoted or not,
which I know often evokes a lot of strong feelings,
it is an incredible achievement
that we were able to transform our view
of the solar system in a matter of years
just by basically charge-coupled devices,
the things that’s in cameras.
Though the invention of that device
allowed us to detect objects
which were much further away, much fainter,
and revealed all of this stuff that was there all along.
And so that’s the beauty of astronomy.
There’s just so much to discover,
and even in our own backyard.
Do you ever think about this?
Do you imagine what are the things
that will completely change astronomy
over the next 100 years?
Like if you transport yourself forward 100 years,
what are the things that will blow your mind
when you look at, wait, what?
Would it be just a very high-resolution mapping of things?
Like, holy crap.
Like one surprising thing might be,
holy crap, there’s like Earth-like moons everywhere.
And another one could be
just totally different devices for sensing.
Yeah, I think usually astronomy moves forward dramatically,
and science in general,
when you have a new technological capability
come online for the first time.
And we kind of just gave examples of that there
with the solar system.
So what kind of new capabilities
might emerge in the next 100 years?
The capability I would love to see is not just,
I mean, in the next 10, 20 years,
we’re hoping to take these pale blue dot images
we spoke about.
So that requires building something like JWST,
but on an even larger scale,
and optimize for direct imaging.
You’d have to have either coronagraph
or a starshade or something to block out the starlight
and reveal those pale blue dots.
So in the next sort of decades,
I think that’s the achievement
that we can look forward to in our lifetimes
is to see photos of other Earths
going beyond that, maybe in our lifetimes,
towards the end of our lifetimes, perhaps.
I’d love it if we,
and I think it’s technically possible
as Breakthrough Starshot
are giving us a lot of encouragement with,
to maybe send a small probe to the nearest stars
and start actually taking high resolution images
of these objects.
There’s only so much you can do from far away
if you want to have,
and we can see it in the solar system.
I mean, there’s only so much you can learn about Europa
by pointing Hubble Space Telescope at it.
But if you really want to understand that moon,
you’re gonna have to send something to orbit it
to hopefully land on it and drill down to the surface.
And so the idea of even taking a flyby
and doing a snapshot photo that gets beamed back
that could be,
doesn’t even have to be more than 100 pixels by 100 pixels.
Even that would be a completely game-changing capability
to be able to truly image these objects.
And maybe at home in our own solar system,
we can certainly get to a point
where we produce crude maps of exoplanets.
One of the, kind of the ultimate limit
of what a telescope could do is governed by its size.
And so the largest telescope you could probably ever build
would be one that was the size of the sun.
There’s a clever trick for doing this
without physically building a telescope
that’s the size of the sun,
and that’s to use the sun as a gravitational lens.
This was proposed, I think, by Von Eschlemann in like 1979,
but it builds upon Einstein’s theory of general relativity,
of course, that there is a warping of light,
a bending of light from the sun’s gravitational field.
And so a distant starlight, it’s like a magnifying glass.
Anything that bends light is basically,
can be used as a telescope.
It’s gonna bend light to a point.
Now it turns out the sun’s gravity is not strong enough
to create a particularly great telescope here
because the focus point is really out in the Kuiper belt.
It’s at 550 astronomical units away from the earth.
So 550 times further away from the sun than we are.
And that’s beyond any of our spacecraft have ever gone.
So you have to send a spacecraft to that distance,
which would take 30, 40 years,
even optimistically improving
our chemical propulsion system significantly.
You’d have to bound it into that orbit,
but then you could use the entire sun as your telescope.
And with that kind of capability,
you could image planets to kilometer scale
or resolution from afar.
And that really makes you wonder.
I mean, if we can conceive, maybe we can’t engineer it,
but if we can conceive of such a device,
what might other civilizations be currently observing
about our own planet?
And perhaps that is why nobody is visiting us,
because there is so much you can do from afar
that to them, that’s enough.
Maybe they can get to the point
where they can detect our radio leakage,
they can direct our terrestrial television signals,
they can map out our surfaces,
they can tell we have cities,
they can even do infrared mapping of the heat island effects
and all this kind of stuff.
They can tell the chemical composition of our planet.
And so that might be enough.
Maybe they don’t need to come down to the surface
and study, do anthropology
and see what our civilization is like.
But there’s certainly a huge amount you can do,
which is significantly cheaper to some degree
than flying there,
just by exploiting cleverly
the physics of the universe itself.
So your intuition is, and this very well might be true,
that observation might be way easier than travel.
From our perspective, from an alien perspective,
like we could get very high resolution imaging
before we could ever get there.
It depends on what information you want.
If you want to know the chemical composition
and you want to know kilometer scale maps of the planet,
then you could do that from afar
with some version of these kind of gravitational lenses.
If you want to do better than that,
if you want to image a newspaper
sat on the porch of somebody’s house,
you’re going to have to fly there.
There’s no way, unless you had a telescope
the size of such a star or something,
you just simply cannot collect enough light
to do that from many light years away.
So there is certainly reasons
why visiting will always have its place,
depending on what kind of information you want.
We’ve proposed in my team, actually,
that the sun is the ultimate pinnacle of telescope design,
but flying to 1,000 AU is a real pain in the butt
because it’s just going to take so long.
And so a more practical way of achieving this
might be to use the Earth.
Now, the Earth doesn’t have anywhere near enough gravity
to create a substantial gravitational lens,
but it has an atmosphere,
and that atmosphere refracts light, it bends light.
So whenever you see a sunset,
just as the sun’s setting below the horizon,
it’s actually already beneath the horizon.
It’s just the light is bending through the atmosphere.
It’s actually already about half a degree down beneath,
and what you’re seeing is that curvature of the light path.
And your brain interprets it, of course,
to be following a straight line
because your brain always thinks that.
And so you can use that bending.
Whenever you have bending, you have a telescope.
And so we’ve proposed to my team
that you could use this refraction
to similarly create an Earth-sized telescope.
Called the Terrascope.
The Terrascope, yeah.
We have a great video on this.
Do you have a paper on the Terrascope?
I do, yeah.
Sometimes I get confused with this
because I’ve heard of an Earth-sized telescope
because of the,
maybe you’ve heard of the Event Horizon Telescope,
which took an image of,
well, it’s taking an image right now
of the center of our black hole.
And it’s very impressive,
and it previously did Messier 87,
a nearby supermassive black hole.
And so those images were interferometric.
So they were small telescopes scattered across the Earth,
and they combined the light paths together,
to create effectively an Earth-sized angular resolution.
Telescopes always have two properties.
There’s the angular resolution,
which is how small of a thing you can see on the surface,
and then there’s the magnification,
how much brighter does that object get
versus just your eye or some small object.
Now, what the Event Horizon Telescope did,
it traded off amplification or magnification
for the angular resolution.
That’s what it wanted.
It wanted that high angular resolution,
but it doesn’t really have much photon-collecting power
because each telescope individually is very small.
The Telescope is different
because it is literally collecting light
with a light bucket,
which is essentially the size of the Earth.
And so that gives you both benefits, potentially,
not only the high angular resolution
that a large aperture promises you,
but also actually physically collects all those photons.
So you can detect light from very, very far away,
the very outer edges of the universe.
And so we propose this as a possible future
technological way of achieving these extreme goals,
ambitious goals we have in astronomy.
It’s a very difficult system to test
because you essentially have to fly out
to these focus points,
and these focus points lie beyond the moon.
So you have to have someone who is willing
to fly beyond the moon
and hitchhike an experimental telescope onto it
and do that cheaply.
If it was something doing low Earth orbit, it’d be easy.
You could just attach a CubeSat
to the next Falcon 9 rocket or something and test it out.
It’d probably only cost you a few tens of thousands of
dollars, maybe a hundred thousand dollars.
There’s basically no one who flies out that far
except for bespoke missions,
such as like a mission that’s going to Mars or something
that would pass through that kind of space.
And they typically don’t have a lot of leeway
and excess payload that they’re willing to strap on
for radical experiments.
So that’s been the problem with it.
In theory, it should work beautifully,
but it’s a very difficult idea to experimentally test.
Can you elaborate why the focal point is that far away?
So you get about half a degree bend
from the Earth’s atmosphere
when you’re looking at the sun at the horizon
and you get that two times over
if you’re outside of the planet’s atmosphere
because it comes, you know,
the star is half a bend to you still on the horizon
and half a degree back out either way.
So you get about a one degree bend.
You take the radius of the Earth,
which is about 7,000 kilometers
and do your arctan function,
you’ll end up with a distance that’s about two,
it’s actually the inner focal point is about two thirds
of the distance of the Earth-moon system.
The problem with that inner focal point is not useful
because that light ray path
had to basically scrape the surface of the Earth.
So it passes through the clouds,
it passes through all the thick atmosphere,
it gets a lot of extinction along the way.
If you go higher up in altitude, you get less extinction.
In fact, you can even go above the clouds
and so that’s even better
because the clouds obviously are gonna be a pain in the neck
for doing anything optical.
But the problem with that is that the atmosphere,
because it gets thinner at higher altitude,
it bends light less.
And so that pushes the focal point out.
So the most useful focal point
is actually about three or four times the distance
of the Earth-moon separation.
And so that’s what we call one of the Lagrange points,
essentially, out there.
And so there is a stable orbit,
it’s kind of the outermost stable orbit
you could have around the Earth.
So the atmosphere does bad things to the signal.
Yeah, it’s absorbing light.
Is it possible to reconstruct, to remove the noise,
whatever, so it’s just strength, it’s nothing else?
It’s possible to reconstruct.
I mean, to some degree we do this,
there’s a technology called adaptive optics
that can correct for what’s called wavefront errors
that happen through the Earth’s atmosphere.
The Earth’s atmosphere is turbulent,
it is not a single plane of air of the same density,
there’s all kind of wiggles and currents in the air.
And so that each little layer is bending light
in slightly different ways.
And so the light actually kind of follows a wiggly path
on its way down.
What that means is that two light rays,
which are traveling at slightly different
spatial separations from each other,
will arrive at the detector at different times,
because one maybe goes on more or less a straight path
and the one wiggles down a bit more before it arrives.
And so you have an incoherent light source.
And when you’re trying to do imagery construction,
you always want a coherent light source.
So the way they correct for this is that this,
if this path had to travel a little bit faster,
the straight one goes faster
and the wiggly one takes longer,
the mirror is deformable.
And so you actually bend the mirror on this,
on the straight one down a little bit
to make it an equivalent light path distance.
So the mirror itself has all these little actuators,
it’s actually made up of like thousands of little elements,
almost looks like a liquid mirror,
because they can manipulate it in kind of real time.
And so they scan the atmosphere with a laser beam
to tell what the deformations are in the atmosphere
and then make the corrections to the mirror
to account for it.
So you could, you could do something like this
for the terrascope, but it would be-
It’s cheaper and easier to go above the atmosphere
and just fly out.
I think so.
It would be very, it’s a very,
that’s a very challenging thing to do.
And normally when you do adaptive optics, as it’s called,
you’re looking straight up.
So you’re, or very close to straight up.
If you look at the horizon,
we basically never do astronomical observations
on the horizon,
because you’re looking through more atmosphere.
If you go straight up,
you’re looking at the thinnest portion of atmosphere
But as you go closer and closer towards the horizon,
you’re increasing what we call the air mass,
the amount of air you have to travel through.
So here it’s kind of the worst case
because you’re going through the entire atmosphere
in and out again with a terrascope.
So you’d need a very impressive adaptive optics system
to correct for that.
So yeah, I would say it’s probably simpler,
at least for proof of principle,
just to test it with having some satellite
that was at a much wider orbit.
Now, speaking of traveling out into deep space,
you already mentioned this a little bit.
You made a beautiful video
called The Journey to the End of the Universe.
And sort of at the start of that,
you’re talking about Alpha Centauri.
So what would it take for humans
or for human-like creatures to travel out to Alpha Centauri?
There’s a few different ways of doing it, I suppose.
One is, it depends on how fast your ship is.
That’s always gonna be the determining factor.
If we devised some interstellar propulsion system
that could travel a fraction of the speed of light,
then we could do it in our lifetimes,
which is, I think, what people normally dream of
when they think about interstellar propulsion and travel,
that you could literally step onto the spacecraft.
Maybe a few years later,
you step off an Alpha Centauri B,
you walk around the surface
and come back and visit your family.
There would be, of course,
a lot of relativistic time dilation
as a result of that trip.
You would have aged a lot less than people back on Earth
by traveling close to the speed of light
for some fraction of time.
The challenge of this, of course,
is that we have no such propulsion system
that can achieve this.
But do you think it’s possible?
Like, so you have a paper called The Halo Drive,
fuel-free relativistic propulsion of large masses
via recycled boomerang photons.
So do you think, first of all, what is that?
And second of all,
how difficult are alternate propulsion systems?
Yeah, so before I took on The Halo Drive,
there was an idea,
because I think The Halo Drive
is not gonna solve this problem.
I’ll talk about The Halo Drive in a moment,
but The Halo Drive is useful for a civilization
which is a bit more advanced than us,
that has spread across the stars,
and is looking for a cheap highway system
to get across the galaxy.
For that first step,
because just to context that,
The Halo Drive requires a black hole.
So that’s why you’re not gonna be able to do this
on the Earth right now.
But there are lots of black holes in the Milky Way,
so that’s the good news.
So we’ll come to that in a moment.
But if you’re trying to travel to Alpha Centauri
without a black hole,
then there are some ideas out there.
There was a Project Daedalus and Project Icarus
that were two projects
that the British Interplanetary Society conjured up
on sort of a 20, 30 year timescale.
And they asked themselves,
if we took existing and speculatively,
but realistic attempts at future technology
that are emerging over the next few decades,
how far could we push into that travel system?
And they settled on fusion drives in that.
So if we had the ability to essentially either detonate,
you can always imagine that kind of nuclear fission
or nuclear fusion bombs going off behind the spacecraft
and propelling it that way,
or having some kind of successful nuclear fusion reaction,
which obviously we haven’t really demonstrated yet
as a propulsion system,
then you could achieve something like 10%
the speed of light in those systems.
But these are huge spacecrafts.
And I think you need a huge spacecraft
if you’re gonna take people along.
The conversation recently has actually switched
and that idea is kind of seems a little bit antiquated now.
And most of us have kind of given up on the idea
of people physically, biologically
stepping on board the spacecraft.
And maybe we’ll be sending something
that’s more like a microprobe
that maybe just weighs a gram or two.
And that’s much easier to accelerate.
You could push that with a laser system to very high speed,
get it to maybe 20% the speed of light.
It has to survive the journey.
Probably a large fraction of them won’t survive the journey,
but they’re cheap enough
that you could maybe manufacture millions of them.
And some of them do arrive and able to send back an image
or maybe even if you wanted to have a person there,
we might have some way of doing like a telepresence
or some kind of delayed telepresence
or some kind of reconstruction of the planet
which is sent back
so you can digitally interact with that environment
in a way which is not real time,
but representative of what that planet
would be like to be on the surface.
So we might be more like digital visitors to these planets,
certainly far easier practically to do that
than physically forcing this wet chunk of meat
to fly across space to do that.
And so that’s maybe something
we can imagine down the road.
The Halo Drive, as I said, is thinking even further ahead.
And if you did want to launch large masses,
large masses could even be planet-sized things
in the case of the Halo Drive,
you can use black holes.
So this is kind of a trick of physics.
You know, I often think of the universe
as like a big computer game
and you’re trying to find cheat codes, hacks,
exploits that the universe didn’t intend for you to use.
But once you find them,
you can address all sorts of interesting capabilities
that you didn’t previously have.
And the Halo Drive does that with black holes.
So if you have two black holes,
which is a very common situation,
a binary black hole,
and they’re in spiraling towards each other,
LIGO has detected, I think, dozens of these things,
maybe even over a hundred at this point.
And these things, as they merge together,
the pre-merger phase,
they’re orbiting each other very, very fast,
even close to the speed of light.
And so Freeman Dyson, before he passed away,
I think in the 70s,
he had this provocative paper called Gravitational Machines,
and he suggested that you could use neutron stars
as a interstellar propulsion system.
And neutron stars are sort of the lower mass version
of a binary black hole system, essentially.
In this case,
he suggested just doing gravitational slingshot,
just fly your spacecraft into this very compact
and relativistic binary system.
And you do need neutron stars
because if there were two stars,
they’d be physically touching each other.
So the neutron stars are so small,
like 10 kilometers across,
they can get really close to each other
and have these very, very fast orbits
with respect to each other.
You shoot your spacecraft through,
right through the middle,
like it’s flying through the eye of a needle,
and you do a slingshot around one of them,
and you do it around the one
that’s coming sort of towards you.
So one will be coming away,
one will be coming towards you at any one point.
And then you could basically steal
some of the kinetic energy in the slingshot.
In principle, you can set up to twice the speed.
You can take your speed,
and it becomes your speed
plus twice the speed of the neutron star in this case.
And that would be your new speed after the slingshot.
This seems great because it’s just free energy, basically.
You’re not doing any,
you’re not generating to have a nuclear power reactor
or anything to generate this,
you’re just stealing it.
And indeed, you can get to relativistic speeds this way.
So I loved that paper,
but I had a criticism.
And the criticism was that this is like
trying to fly your ship into a blender, right?
This is two neutron stars,
which have huge tidal forces.
And they’re whipping around each other
once every second or even less than a second.
And you’re trying to fly your spaceship
and do this maneuver that is pretty precarious.
And so it just didn’t seem practical to me
to have to do this, but I loved it.
And so I took that idea,
and this is how science is.
You take a previous great man’s idea
and you just sort of maybe slightly tweak it and improve it.
That’s how I see the Hiller drive.
And I just suggested,
why not replace those out for black holes?
Which is certainly very common.
And rather than flying your ship
into that hell hole of a blender system,
you just stand back and you fire a laser beam.
Now, because black holes
have such intense gravitational fields,
they can bend light into complete 180s.
They can actually become mirrors.
So the sun bends light by maybe a fraction of a degree
through gravitational lensing,
but a compact object like a black hole can do a full 180.
In fact, obviously, if you went too close,
if you put the laser beam too close,
the black hole would just fall into it
and never come back out.
So you just kind of push it out, push it out, push it out
until you get to a point
where it’s just skirting the event horizon.
And then that laser beam skirts around and it comes back.
Now, the laser beam wants to do a,
I mean, it is doing a gravitational slingshot,
but laser, I mean, light photons can’t speed up
unlike the spaceship case.
So instead of speeding up,
the way they steal energy is they increase their frequency.
So they become higher energy photon packets, essentially.
They get blue shifted so that you send
maybe a red laser beam that comes back blue.
It’s got more energy in it.
And because photons carry momentum,
which is somewhat unintuitive in everyday experience,
but they do, that’s how solar sails work.
They carry momentum, they push things.
You can even use them as laser tweezers
and things to pick things up.
Because they push,
it comes back with more momentum than it left.
So you get an acceleration force from this.
And again, you’re just seeing energy
from the black hole to do that.
So you can get up to the same speed.
It’s basically the same idea as Freeman Dyson,
but doing it from a safer distance.
And there should be of order of a million or so
or 10 million black holes in the Milky Way galaxy.
Some of them would be even as close
as sort of 10 to 20 light years
when you do the occurrence rate statistics
of how close you might expect, feasibly want to be.
They’re of course difficult to detect because they’re black.
And so they’re inherently hard to see.
But statistically, there should be plenty out there
in the Milky Way.
And so these objects would be natural waypoint stations.
You could use them to both accelerate away
and to break and slow down.
And on top of all this,
you know, we’ve been talking about astronomy and cosmology.
There’s been a lot of exciting breakthroughs
in detection and exploration of black holes.
So the boomerang photons that you’re talking about,
there’s been a lot of work on photon rings
and just all the fun stuff going on outside the black holes.
So all the garbage outside is actually might be the thing
that holds a key to understanding what’s going on inside.
And there’s the Hawking radiation.
There’s all kinds of fascinating stuff like,
I mean, there’s trippy stuff about black holes
that I can’t even, well, most people don’t understand.
I mean, the holographic principle with the plate
and the information being stored potentially outside
of the black hole.
I don’t even, I can’t even comprehend
how you can project a three-dimensional object
onto a 2D and somehow store information
where it doesn’t destroy it.
And if it does destroy it, challenging all the physics.
All of this is very interesting,
especially for kind of more practical applications
of how the black hole can be used for propulsion.
Yeah, I mean, it may be that black holes are used
in all sorts of ways by advanced civilizations.
I think, again, it’s been a popular idea
in science fiction or science fiction trope
that Sagittarius A star, the supermassive black hole
in a centrified galaxy could be the best place
to look for intelligent life in the universe
because it is a giant engine in a way.
You know, a unique capability of a black hole
is you can basically throw matter into it
and you can get these jets that come out,
the accretion disks and the jets that fly out.
And so you can more or less use them to convert matter
into energy V equals MC squared.
And there’s pretty much nothing else
except for annihilation with its own antiparticle
as a way of doing that.
So they have some unique properties.
You could perhaps power a civilization
by just throwing garbage into a black hole, right?
Just throwing asteroids in and power your civilization
with as much energy as you really would ever plausibly need.
And you could also use them to accelerate
away across the universe.
And you can even imagine using small artificial black holes
as thermal generators, right?
So the Hawking radiation from them
kind of exponentially increases
as they get smaller and smaller in size.
And so a very small black hole,
one that you can almost imagine like holding in your hand
would be a fairly significant heat source.
And so that raises all sorts of prospects
about how you might use that in an engineering context
to power your civilization as well.
Oh, you have a video
on becoming a Kardashev Type I civilization.
What’s our hope for doing that?
We’re a few orders of magnitude away from that.
Yeah, it is surprising.
I think people tend to think
that we’re close to this scale.
The Kardashev Type I is defined as a civilization
which is using as much energy
as is essentially incident upon the planet from the star.
So as of order, I think for the Earth
of something like 10 to the five terawatts
or 10 to the seven terawatts
is a gigantic amount of energy.
And we’re using a tiny, tiny, tiny fraction
of that right now.
So if you became a Kardashev Type I civilization,
which is seen not necessarily as a goal into itself,
I think people think, well, why are we aspiring
to become this energy hungry civilization?
Surely our energy needs might improve our efficiency
or something as time goes on.
But ultimately the more energy you have access to,
the greater your capabilities will be.
I mean, if you wanna lift Mount Everest into space,
there is just a calculable amount of potential energy change
that that’s going to take in order to accomplish that.
And the more energy you have access to as a civilization,
then clearly the easier that energy achievement
is going to be.
So it depends on what your aspirations are
as a civilization.
It might not be something you wanna ever do, but.
Well, but we should make clear
that lifting heavy things isn’t the only thing.
It’s just doing work.
So it could be computation.
It could be more and more and more and more sophisticated
and larger and larger and larger computation,
which is, it does seem where we’re headed
with the very fast increase in the scale
and the quality of our computation
outside the human brain, artificial computation.
Yeah, I mean, computation is a great example of,
I mean, already I think something like 10%
of US power electricity use
is going towards the supercomputing centers.
There’s a vast amount of current energy needs
which are already going towards computing
and will surely only increase over time.
If we start ever doing anything like mind uploading
or creating simulated realities,
that cost will surely become almost a dominant source
of our energy requirements at that point
if civilization completely moves over
to this kind of post-humanism stage.
And so it’s not unreasonable that our energy needs
would continue to grow.
Certainly historically, they always have
at about 2% per year.
And so if that continues,
there is gonna be a certain point
where you’re running up against the amount of energy
which you can harvest
because you’re using,
even if you cover the entire planet in solar panels,
there’s no more energy to be had.
And so there’s a few ways of achieving this.
I sort of talked about in the video
how there were several renewable energy sources
that we’re excited about,
like geothermal, wind power, waves,
but pretty much all of those
don’t really scratch the surface
or don’t really scratch the itch
of getting to a Kardashev type one civilization.
They’re meaningful now.
I would never tell anybody don’t do wind power now
because it’s clearly useful
at our current stage of civilization,
but it’s gonna be a pretty negligible fraction
of our energy requirements
if we got to that stage of development.
And so there has to be a breakthrough
in either our ability to harvest solar energy,
which would require maybe something like a space array
of solar panels of beaming the energy back down,
or some developments and innovations in nuclear fusion
that would allow us to essentially
reproduce the same process
of what’s producing the solar photons, but here on Earth.
But even that comes with some consequences.
If you’re generating the energy here on Earth
and you’re doing work on it on Earth,
then that work is gonna produce waste heat,
and that waste heat is gonna increase
the ambient temperature of the planet.
And so even if this isn’t really a greenhouse effect
that you’re increasing the temperature of the planet,
this is just the amount of computers that are churning.
You put your hand to a computer,
you can feel the warmth coming off them.
If you do that much work of literally
the entire instant energy of the planet is doing that work,
the planet’s gonna warm up significantly
as a result of that.
And so that clearly indicates
that this is not a sustainable path,
that civilizations, as they approach Kailashev Type I,
are gonna have to leave planet Earth,
which is really the point of that video,
to show that it’s, a Kailashev Type I civilization,
even though it’s defined as instant energy upon a planet,
that is not a species that is gonna still be living
on their planet, at least in isolation.
They will have to be harvesting energy from afar,
they will have to be doing work on that energy
outside of their planet,
because otherwise you’re gonna dramatically change
the environment in which you live.
Well, yeah, so the more energy you create,
the more energy you use,
the more, the higher the imperative
to expand out into the universe,
but also not just the imperative, but the capabilities.
And you’ve kind of, as a side on your lab page,
mentioned that you’re sometimes interested
in astroengineering, so what kind of space architectures
do you think we can build to house humans
that are interesting things outside of Earth?
Yeah, I mean, there’s a lot of fun ideas here.
One of the classic ideas is an O’Neill cylinder,
or a Stanford torus.
These are like two rotating structures
that were devised in space.
They’re basically using the centrifugal force
as artificial gravity, and so these are structures
which tend to be many kilometers across
that you’re building in space,
but could potentially habitat millions of people
in orbit of the Earth.
Of course, you could imagine putting them,
if the expanse does a pretty good job, I think,
of exploring the idea of human exploration
of the solar system and having many objects,
many of the small near-Earth objects and asteroids
inhabited by mining colonies.
One of the ideas we’ve played around with our group
is this technology called a quasite.
A quasite is an extension, again,
we always tend to extend previous ideas.
Ideas build upon ideas.
An extension idea called a statite.
A statite was an idea proposed, I think,
by Ron Forwood in the 1970s.
1970s seemed to have all sorts of wacky ideas.
I don’t know what was going on then.
I think the Stanford torus, the O’Neill cylinder, statites,
the gravitational lens, people were really having fun
with dreaming about space in the 70s.
The statite is basically a solar sail,
but it’s such an efficient solar sail
that the outward force of radiation pressure
equals the inward force of gravity from the sun.
And so it doesn’t need to orbit.
Normally you avoid, the sun is pulling on us right now
through force of gravity, but we are not getting closer
towards the sun, even though we are falling towards the sun
because we’re in orbit, which means our translational speed
is just enough to keep us at the same altitude,
essentially, from the sun.
And so you’re in orbit,
and that’s how you maintain distance.
A statite doesn’t need to do that.
It could be basically completely static in inertial space,
but it’s just balancing the two forces
of radiation pressure and inward gravitational pressure.
A quasite is the in-between of those two states.
So it has some significant outward pressure,
but not enough to resist fully falling into the star.
And so it compensates for that
by having some translational motion.
So it’s in between an orbit and a statite.
And so what that allows you to do
is maintain artificial orbits.
So normally, if you want to calculate your orbital speed
of something at, say, half an AU,
you would use Kepler’s third law and go through that,
and you’d say, okay, if it’s at half an AU,
I can calculate the period by p squared
as proportional to a cubed and go through that.
But for a quasite, you can basically have any speed you want.
It’s just a matter of how much of the gravitational force
are you balancing out.
You effectively enter an orbit
where you’re making the mass of the star
be less massive than it really is.
So it’s as if you were orbiting a 0.1 solar mass star
or a 0.2 solar mass star, whatever you want.
And so that means that Mercury orbits
with a pretty fast orbital speed around the sun
because it’s closer to the sun than we are.
But we could put something in Mercury’s orbit
that would have a slower speed,
and so it would co-track with the Earth.
And so we would always be aligned with them at all times.
And so this could be useful
if you wanted to have either a chain of colonies
or something that were able to easily communicate
and move between one another, between these different bases.
You’d probably use something like this
to maintain that easy transferability.
Or you could even use it
as a space weather monitoring system,
which was actually proposed in the paper.
We know that major events like the Carrington event
that happened, it can knock out
all of our electromagnetic systems quite easily.
A major solar flare could do that, a geomagnetic storm.
But if we had the ability to detect
those higher elevated activity cycles in advance,
the problem is they travel, obviously, pretty fast,
and so it’s hard to get ahead of them.
But you could have a station
which is basically sampling solar flares
very close to the surface of the Earth,
and as soon as it detects anything suspicious magnetically,
it could then send that information
straight back at the speed of light to your Earth
and give you maybe a half an hour warning or something,
that something bad was coming,
and you should shut off all your systems
or get in your Faraday cage now and protect yourself.
And so these quasites are kind of a cool trick
of, again, kind of hacking the laws of physics.
It’s like another one of these exploits
that the universe seems to allow us to do
to potentially manifest these artificial systems
that would otherwise be difficult to produce.
So leveraging natural phenomena.
That’s always the key, is to work,
in my mind, is to work with nature.
That’s how I see astroengineering, rather than against it.
You’re not trying to force it to do something.
That’s why I always think solar energy is so powerful,
because in the battle against nuclear fusion,
you’re really fighting a battle
where you’re trying to confine plasma
into this extremely tight space.
The sun does this for free.
It has gravitation.
And so that’s, in essence, what a solar panel does.
It is a nuclear fusion reactor-fueled energy system,
but it’s just using gravitation for the confinement
and having a huge standoff distance
for its energy collection.
And so there are tricks like that.
It’s a very naive, simple trick in that case,
where we can, rather than having to reinvent the wheel,
we can use the space infrastructure, if you like,
the astrophysical infrastructure
that’s already there to our benefit.
Yeah, I think in the long arc of human history,
probably natural phenomena is the right solution.
That’s the simple, that’s the elegant solution,
because all the power’s already there.
That’s why a Dyson sphere in the long, sort of,
well, you don’t know what a Dyson sphere would look like,
but some kind of thing that leverages the power,
the energy that’s already in the sun,
is better than creating artificial nuclear fusion reaction.
But then again, that brings us to the topic of AI.
How much of this, if we’re traveling out there,
interstellar travel, or doing some of the interesting things
we’ve been talking about,
how much of those ships would be occupied
by AI systems, do you think?
What would the,
what would be the living organisms occupying those ships?
Yeah, it’s depressing to think about AI
in the search for life, because it has,
I mean, I’ve been thinking about this a lot
over the last few weeks with playing around
with Chat GPT-3, like many of us,
and being astonished with its capabilities.
And you see that our society is undergoing a change
that seems significant in terms of the development
of artificial intelligence.
We’ve been promised this revolution,
this singularity for a long time,
but it really seems to be stepping up
its pace of development at this point.
And so that’s interesting, because as someone
who looks for alien life out there in the universe,
it sort of implies that our current stage of development
is highly transitional, and that, you know,
you go back for the last four and a half billion years,
the planet was dumb, essentially.
If you go back the last few thousand years,
there was a civilization,
but it wasn’t really producing any technosignatures.
And then over the last maybe hundred years,
there’s been something that might be detectable from afar.
But we’re potentially approaching this cusp
where we might imagine it, I mean,
we’re thinking of like maybe years and decades
with AI development, typically when we talk about this,
but as an astronomer, I have to think about
much longer timescales of centuries,
millennia, millions of years.
And so if this wave continues over that timescale,
which is still the blink of an eye on a cosmic timescale,
that implies that everything will be AI,
essentially, out there,
if this is a common behavior.
And so that’s intriguing,
because it sort of implies that we are special
in terms of our moment in time as a civilization,
which normally is something
we’re averse to as astronomers.
We normally like this mediocrity principle,
we’re not special, we’re a typical part of the universe,
similar to the cosmological principle.
But in a temporal sense, we may be in a unique location.
And perhaps that is part of the solution
to the Fermi paradox, in fact,
that if it is true that planets tend to go through
basically three phases,
dumb life for the vast majority,
a brief period of biological intelligence,
and then an extended period of artificial intelligence
that they transition to,
then we would be at a unique and special moment
in galactic history that would be of particular interest
for any anthropologists out there in the galaxy, right?
This would be the time
that you would want to study a civilization very carefully.
You wouldn’t want to interfere with it,
you would just want to see how it plays out.
Kind of similar to the ancestor simulations,
though sometimes talked over the simulation argument,
that you are able to observe perhaps your own origins
and study how the transformation happens.
And so yeah, that has for me recently been throwing
the Fermi paradox a bit on its head.
And this idea of the zoo hypothesis that we may be monitored
which has for a long time been sort of seen as a fringe idea
even amongst the SETI community.
But if we live in this truly transitional period,
it adds a lot of impetus to that idea, I think.
Well, even AI itself would,
by its very nature, would be observing us.
By, you know, it’s like a human,
there used to be this concept of human computation,
which is actually exactly what’s feeding
the current language models,
which is leveraging all the busy stuff we’re doing
to do the hard work of learning.
So like the language models are trained
on human interaction and human language on the internet.
And so AI feeds on the output of brain power from humans.
And so like it would be observing and observing
and it gets stronger as it observes.
So it actually gets extremely good at observing humans.
And one of the interesting philosophical questions
that starts percolating is what makes us,
what is the interesting thing that makes us human?
We tend to think of it,
and you said like there’s three phases.
What’s the thing that’s hard to come by in phase three?
Is it something like scarcity, which is limited resources?
Is it something like consciousness?
Is that the thing that’s very,
that emerged the evolutionary process in biological systems
that are operating under constrained resources?
This thing that feels,
that it feels like something to experience the world,
which we think of as consciousness,
is that really difficult to replicate in artificial systems?
Is that the thing that makes us fundamentally human?
Or is it just a side effect
that we attribute way too much importance to?
Do you have a sense,
if we look out into the future and AI systems
are the ones that are traveling out there
to Alpha Centauri and beyond,
do you think they have to carry
the flame of consciousness with them?
No, not necessarily.
They may do, but they may,
it may not be unnecessarily,
I mean, I guess we’re talking about the difference here
between sort of an AGI, artificial general intelligence,
or consciousness, which are distinct ideas,
and you can certainly have one without the other.
So I could imagine.
I would disagree with this certainly in that statement.
I think it’s very possible
in order to have intelligence,
you have to have consciousness.
Okay, well, I mean, to a certain degree,
GPT-3 has a level of intelligence already.
It’s not a general intelligence,
but it displays properties of intelligence
with no consciousness, so.
Again, I would disagree.
Well, I don’t know.
Because you said, it’s very nice that you said
it displays properties of intelligence
in the same way it displays properties of intelligence,
I would say it’s starting to display
properties of consciousness.
It certainly could fool you that it’s conscious.
So there’s, I guess, like a Turing test problem.
Like, if it’s displaying all those properties,
if it quacks like a parrot, looks like a parrot,
or quacks like a duck,
things like, isn’t it basically a duck at that point?
So yeah, I can see that argument.
It probably, I mean, certainly as an,
I tried to think about it
from the observer’s point of view as an astronomer.
What am I looking for?
Whether that intelligence is conscious or not
has little bearing, I think,
as to what I should be looking for
when I’m trying to detect evidence of them.
It would maybe affect their behavior
in ways that I can’t predict.
But that’s, again, getting into the game
of what I would call xenopsychology,
of trying to make projections
about the motivations of an alien species
is incredibly difficult.
And similarly, for any kind of artificial intelligence,
it’s unfathomable what its intentions may be.
I mean, I would sort of question
whether it would even be interested
in traveling between the stars at all.
If its primary goal is computation,
computation for the sake of computation,
then it’s probably gonna have a different way of,
it’s gonna be engineering its solar system
and the nearby material around it for a different goal
if it’s just simply trying to increase
computer substrate across the universe.
And that, of course, if that is its principal intention
to just essentially convert dumb matter
into smart matter as it goes,
then I think that would come into conflict
with our observations of the universe, right?
Because the Earth shouldn’t be here if that were true.
The Earth should have been transformed
into computer substrate by this point.
There has been plenty of time
in the history of the galaxy for that to have happened.
So I’m skeptical that we can,
I’m skeptical in the part that that’s a behavior
that AI or any civilization really engages in,
but I also find it difficult to find a way out of it,
to explain why that would never happen
in the entire history of the galaxy
amongst potentially, if life is common,
millions, maybe even billions of instant instantiations
of AI could have occurred across the galaxy.
And so that seems to be a knock against the idea
that there is life else, or intelligent life else
around in the galaxy.
The fact that that hasn’t occurred in our history
is maybe the only solid data point we really have
about the activities of other civilizations.
Of course, the scary one could be that
we just at this stage,
intelligent alien civilizations
just started destroying themselves.
It becomes too powerful.
Everything’s just too many weapons,
too many nuclear weapons,
too many nuclear weapon style systems
that just from mistake to aggression,
like the probability of self-destruction is too high
relative to the challenge of avoiding,
the technological challenges of avoiding self-destruction.
Do you mean that the AI destroys itself,
or we destroy ourselves prior to the advent of AI?
As we get smarter and smarter,
AI, either AI destroys us or other,
there could be just a million,
like AI is correlated,
the development of AI is correlated
with all this other technological innovation.
all kinds of engineering at the nanoscale,
mass manufacture of things that could destroy us,
cracking physics enough to have very powerful weapons,
nuclear weapons, all of it, just too much.
Physics enables way too many things that can destroy us
before it enables the propulsion systems
that allow us to fly far enough away
before we destroy ourselves.
So maybe that’s what happens
to the other alien civilizations.
Is that your resolution?
Because I mean, I think us in the technosignature community
aren’t thinking about this problem seriously enough,
in my opinion.
We should be thinking about what AI is doing to our society
and the implications, what we’re looking for.
And so the only, I think part of this thinking
has to involve people like yourself
who are more intimate with the machine learning
and artificial intelligence world.
How do you reconcile in your mind,
you said earlier that you think
you can’t imagine a galaxy where life and intelligence
is not all over the place.
And if artificial intelligence is a natural progression
for civilizations, how do you reconcile that
with the absence of any information around us?
So any clues or hints of artificial behavior,
artificially engineered stars or colonization,
computer substrate, transform planets, anything like that?
It’s extremely difficult for me.
The Fermi paradox broadly defined
is extremely difficult for me.
And the terrifying thing is one thing I suspect
is that we keep destroying ourselves.
The probability of self-destruction
with advanced technology is just extremely high.
That’s why we’re not seeing it.
But then again, my intuition about why we haven’t
blown ourselves up with nuclear weapons,
it’s very surprising to me from a scientific perspective.
Given all the cruelty I’ve seen in the world,
given the power that nuclear weapons place in the hands
of a very small number of individuals,
it’s very surprising to me that we destroy ourselves.
And it seems to be a very low probability situation
we have happening here.
But, and then the other explanation is the zoo,
is the observation that we’re just being observed.
That’s the only other thing.
It’s just, it’s so difficult for me.
Of course, all of science, everything is very humbling.
It would be very humbling for me to learn
that we’re alone in the universe.
It would change, you know what?
Maybe I do want that to be true
because you want us to be special.
That’s why I’m resisting that thought maybe.
There’s no way we’re that special.
There’s no way we’re that special.
That’s where my resistance comes from.
I would just say, you know, the specialness is something,
we, implicitly in that statement,
there’s kind of an assumption
that we are something positive.
Like we’re a gift to this planet or something
and that makes us special.
But it may be that intelligence is more of an,
it’s like we’re like rats or cockroaches.
We’re an infestation of this planet.
We’re not some benevolent property
that a planet would ideally like to have,
if you can even say such a thing.
We may be not only generally a negative force
for a planet’s biosphere and its own survivability,
which I think you can make a strong argument about,
but we may also be a very persistent infestation
that may, even in, you know, interesting thoughts,
in the wake of a nuclear war,
would that be an absolute eradication of every human being,
which would be a fairly extreme event?
Or would the candela consciousness,
as you might call it, the flame of consciousness,
continue with some small pockets
that would maybe in 10,000 years, 100,000 years,
we’d see civilization reemerge
and play out the same thing over again?
Yeah, that’s certainly,
but nuclear weapons aren’t powerful enough yet.
But yes, but to sort of push back on the infestation,
sure, but the word special doesn’t have to be positive.
I just mean-
I think it tends to imply, but I take your point, yeah.
But maybe, just maybe extremely rare might be.
Yeah, and that, to me, it’s very strange
for me to be cosmically unique.
It’s just very strange.
I mean, that we’re the only thing
of this level of complexity in the galaxy
just seems very strange to me.
I would just, yeah, I do think it depends
on this classification.
I think there is sort of, again,
it’s kind of buried within there as a subtext,
but there is a classification that we’re doing here
that what we are is a distinct category of life,
let’s say, in this case, when we’re talking about intelligence
we are something that can be separated.
But of course, we see intelligence across the animal kingdom
in dolphins, humpback whales, octopuses,
crows, ravens, and so it’s quite possible
that these are all manifestations of the same thing.
And we are not a particularly distinct class,
except for the fact we make technology.
That’s really the only difference to our intelligence.
And we classify that separately,
but from a biological perspective, to some degree,
it’s really just all part of a continuum.
And so that’s why, when we talk about unique,
you are putting yourself in a box which is distinct
and saying this is the only example of things
that fall into this box.
But the walls of that box may themselves be a construct
of our own arrogance that we are something distinct.
But I was also speaking broadly for us,
meaning all life on earth,
but then it’s possible that there’s all kinds
of living ecosystems on other planets and other moons
that just don’t have interest in technological development.
Maybe technological development is the parasitic thing
that destroys the organism broadly.
And then maybe that’s actually one
of the fundamental realities.
Whatever broad way to categorize technological development,
that’s just the parasitic thing that just destroys itself.
It’s a cancer.
We’re floating around, sorry to interrupt.
We’re floating around this idea of the great filter
a little bit here.
So we’re asking, where is this?
Does it lie ahead of us?
Nuclear war may be imminent.
That would be a filter that’s ahead of us.
Or could it be behind us?
And that it’s the advent of technology
that is genuinely a rare occurrence in the universe.
And that explains the Fermi paradox.
And so that’s something that obviously people have debated
and argued about in SETI for decades and decades.
But it remains a persistent,
people argue whether it should be really called
a paradox or not.
But it remains a consistent apparent contradiction
that you can make a very cogent argument
as to why you expect life and intelligence
to be common in the universe.
And yet everything, everything we know about the universe
is fully compatible with just us being here.
And that’s a haunting thought.
But I’m not, I have no preference or desire
for that to be true.
I’m not trying to impose that view on anyone.
But I do ask that we remain open-minded
until evidence has been collected either way.
The thing is, it’s one of, if not the,
probably I would argue it’s the most important question
facing human civilization, or the most interesting.
I think scientifically speaking,
what question is more important than,
somehow, there could be other ways to sneak up to it,
but it gets to the essence of what we are,
what these living organisms are.
It’s somehow seeing another kind helps us understand.
It speaks to the human condition,
helps us understand what it is to be human to some degree.
Um, I think, you know, I have tried to remain very agnostic
about the idea of life and intelligence.
One thing I try to be more optimistic about,
and I’ve been thinking a lot with our searches
for life in the universe, is life in the past.
You can, I think it’s actually not that hard
to imagine we are the only civilization
in the galaxy right now living.
Yeah, to this current extent.
But there may be very many extinct civilizations.
If each civilization has a typical lifetime
comparable to, let’s say, AI is the demise of our own,
that’s only a few hundred years of technological development,
or maybe 10,000 years if you go back
to the Neolithic Revolution, the dawn of agriculture.
You know, hardly anything in cosmic time span.
That’s nothing, that’s the blink of an eye.
And so it’s not surprising at all
that we would happen not to coexist with anyone else.
But that doesn’t mean nobody else was ever here.
And if other civilizations come to that same conclusion
and realization, maybe they scour the galaxy around them,
don’t find any evidence for intelligence,
then they have two options.
They can either give up on communication
and just say, well, it’s never gonna happen.
We just may as well just, you know,
worry about what’s happening here on our own planet.
Or they could attempt communication,
but communication through time.
And that’s almost the most selfless act of communication,
because there’s no hope of getting anything back.
It’s a philanthropic gift, almost,
to that other civilization that you can,
maybe it might just be nothing more than a monument,
which the pyramids essentially are,
a monument of their existence,
that these are the things they achieved,
this was their, you know, the things they believed in,
their language, their culture.
Or it could be maybe something more than that.
It could be sort of lessons from what they learned
in their own history.
And so, I’ve been thinking a lot recently about
how would we send a message
to other civilizations in the future?
Because that act of thinking seriously
about the engineering of how we would design it
would inform us about what we should be looking for,
and also perhaps be our best chance, quite frankly,
of ever making contact.
It might not be the contact we dream of,
but it’s still contact.
There would still be a record of our existence,
as pitiful as it might be
compared to a two-way communication.
And I love the humility behind that project,
that universal project.
It’s sort of, it’s humble.
It humbles you to the vast
temporal landscape of the universe,
just realizing our day-to-day lives,
all of us will be forgotten
and it’s nice to think about something
that sends a signal out to other, yeah.
Other life forms.
It was almost like a humility of acceptance as well,
of knowing that you have a terminal disease,
but your impact on the Earth
doesn’t have to end with your death,
that it could go on beyond with what you leave behind
for others to discover with maybe the books you write
or what you leave in the literature.
Do you think launching the Roadster vehicle
out in space would have done better?
Yeah, yeah, the Roadster.
I’m not sure what someone would make of that,
if they found it.
Yeah, that’s true.
I mean, there have been quasi attempts at it
beyond the Roadster.
I mean, there’s like plaques on,
there’s the Pioneer plaques,
there’s the Voyager 2 Golden Record.
It’s pretty unlikely anybody’s gonna discover those
because they’re just adrift in space
and they will eventually mechanically die
and not produce any signal for anyone to spot.
So you’d have to be extremely lucky to come across them.
I’ve often said to my colleagues
that I think the best place is the moon.
The moon, unlike the Earth, has no significant weathering.
How long will the Apollo descent stages,
which are still sun on the lunar surface, last for?
The only real effect is micrometeorites,
which are slowly like dust
smashing against them pretty much.
But that’s gonna take millions,
potentially billions of years to erode that down.
And so we have an opportunity, and that’s on the surface.
If you put something just a few meters beneath the surface,
it would have even greater protection.
And so it raises the prospect of that
if we wanted to send something,
a significant amount of information,
to a future galactic-spanning civilization
that maybe cracks the interstellar propulsion problem,
the moon’s gonna be there for five billion years.
That’s a long time for somebody to come by
and detect maybe a strange pattern
that we draw on the sand,
for them to, you know, big arrow, big cross,
like, look under here,
and we could have a tomb of knowledge
of some record of our civilization.
And so I think it’s,
when you think like that, what that implies to us,
well, okay, the galaxy’s 13 billion years old,
the moon is already four billion years old.
There may be places familiar to us, nearby to us,
that we should be seriously considering
as places we should look for life,
and intelligent life, or evidence of relics
that they might leave behind for us.
So that thinking like that will help us find such relics,
and it’s like a beneficial cycle that happens.
Yes, yeah, exactly.
That enables the science of society better,
like of searching for bios and tech signatures and so on.
And it’s inspiring.
I mean, it’s also inspiring in that we wanna leave
a legacy behind as an entire civilization,
not just in the symbols, but broadly speaking.
That’s the last thing somehow.
Yeah, and I’m part of a team
that’s trying to repeat the Golden Record experiment.
We’re trying to create like an open source version
of the Golden Record that future spacecraft
are able to download,
and basically put in a little hard drive
that they can carry around with them,
and, you know, get these distributed,
hopefully across the solar system eventually.
So it’s gonna be called
the Hitchhiker’s Guide to the Galaxy, right?
Yeah, it could be.
That’s a good name for it.
We’ve been toying a little bit with the name,
but I think probably it would just be Golden Record
at this point, or Golden Record version two or something.
But I think another benefit that I see of this activity
is that it forces us as a species to ask those questions
about what it is that we want another civilization
to know about us.
The Golden Record was kind of funny
because it had photos on it,
and it had photos of people eating, for instance,
but it had no photos of people defecating.
And so I always thought that was kind of funny
because if I was an alien, or if I was studying an alien,
if I saw images of an alien,
I would, I’m not trying to be like a perv or anything,
but I would want to see the full,
I want to understand the biology of that alien.
And so we always censor what we show,
and we should show the whole actual natural process,
and then also say, we humans tend to censor these things.
We tend to not like to walk around naked,
we tend to not to talk about
some of the natural biological phenomena
and talk a lot about others,
and actually just be very,
like the way you would be to a therapist or something,
very transparent about the way we actually operate.
Yeah, I mean, and Sagan had that with the Golden Record.
I think he originally,
there’s a male and a female figure
to pitch on the Golden Record.
And the woman had a genitalia originally drawn,
and there was a lot of pushback
from I think a lot of Christian groups
who were not happy about the idea of throwing this into space
and so eventually they had to remove that.
And so it would be confusing biologically
if you’re trying to study xenobiology of this alien
that apparently has no genitalia,
or the man does, but for some reason the woman doesn’t.
And that’s our own societal and cultural imprint
happening into that information.
That’s, to be fair,
just even having two sexes and predators and prey,
just the whole,
that could be just a very unique Earth-like thing.
So they might be confused about
why there’s like pairs of things.
Like, why are you,
why is there a man and a woman in general?
Like, they could be, I mean,
they could be confused about a lot of things in general.
I don’t think the-
I don’t even know which way to hold the picture.
Or there’s the picture.
They don’t, they might not need,
they might have very different sensory devices
to even interpret this.
If they only have sound
as their only way of navigating the world,
it’s kind of lost to send any kind of,
there’s been a lot of conversation about sending video
and audio and video and pictures.
that’s one of the things I’ve been
a little bit resistant about in the team
that I’ve been thinking,
well, they might not have eyes.
And so if you lived in,
under Europa’s surface,
having eyes wouldn’t be very useful.
If you lived in a,
on a very dark planet,
on the tidally locked night side of an exoplanet,
having eyes wouldn’t be particularly useful.
So it’s kind of a presumption of us
to think that video is a useful form of communication.
Do you hope we become a multi-planetary species?
almost sneaking up to that,
but you know,
the efforts of SpaceX, of Elon,
maybe in general,
what your thoughts are about those efforts?
So you already mentioned Starship
will be very interesting for astronomy,
for science in general,
just getting stuff out into space.
But what about the longer term goal
of actually colonizing,
of building civilizations on other surfaces,
on moons, on planets?
It seems like a fairly obvious thing
to do for our survival, right?
There’s a high risk.
If we are committed to trying to keep
this human experiment going,
putting all of our eggs in one basket
is always gonna be a risky strategy to pursue.
It’s a nice basket though, but yeah.
It is a beautiful basket.
I wouldn’t wanna,
I personally have no interest in living on Mars
or the moon.
I would like to visit,
but I would definitely not wanna spend
the rest of my life and die on Mars.
I mean, it’s a hell hole.
Mars is a very, very different,
I think the idea that this is gonna happen
in the next 10, 20 years
seems to me very optimistic.
Not that it’s insurmountable,
but the challenges are extreme
to survive on a planet like Mars,
which is like a dry, frozen desert
with a high radiation environment.
It’s a challenge of a type we’ve never faced before.
So it’s, I’m sure human ingenuity
can tackle it,
but I’m skeptical that we’ll have thousands of people
living on Mars in my lifetime.
But I would relish that opportunity
to maybe one day visit such a settlement
and do scientific experiments on Mars
or experience Mars,
do astronomy from Mars,
all sorts of cool stuff you could do.
Sometimes you see these dreams
of outer solar system exploration
and you can fly through the clouds of Venus
or you could just do these enormous jumps
on like these small moons
where you can essentially jump as high as a skyscraper
and traverse the moon.
So there’s all sorts of wonderful ice skating on Europa,
might be fun.
So don’t get me wrong,
I love the idea of us becoming interplanetary.
I think it’s just a question of time.
Our own destructive tendencies,
as you said earlier,
are at odds with our emerging capability
to become interplanetary.
And the question is,
will we get out of the nest before we burn it down?
And I don’t know,
obviously I hope that we do,
but I don’t have any special insight that,
there is a problem,
there is somewhat of a
annoying intellectual itch I have
with the so-called doomsday argument,
which I try not to treat too seriously,
but there is some element of it that bothers me.
The doomsday argument basically suggests
that you’re typically,
the mediocrity principle,
you’re not special,
that you’re probably gonna be born
somewhere in the middle of all human beings
who will ever be born.
You’re unlikely to be one of the first 1% of human beings
that ever lived
and similarly the last 1% of human beings
that will ever live,
because you’d be very unique and special if that were true.
And so by this logic,
you can sort of calculate
how many generations of humans you might expect.
So if there’s been,
let’s say 100 billion human beings
that have ever lived on this planet,
then you could say to 95% confidence,
so you divide by 5%,
so 100 billion divided by 0.05
would give you 2 trillion human beings
that would ever live,
you’d expect by this argument.
And so if each,
let’s say each planet,
in general the planet has a 10 billion population,
so that would be 200 generations of humans
we would expect ahead of us.
And if each one has an average lifetime,
let’s say 100 years,
then that would be about 20,000 years.
So there’s 20,000 years left in the clock.
That’s like a typical doomsday argument type,
that’s how they typically lay it out.
Now you can,
a lot of the criticisms of the doomsday argument
come down to what are you really counting?
You’re counting humans there,
but maybe you should be counting years
or maybe you should be counting human hours
because what you count makes a big difference
to what you get out on the other end.
So this is called the reference class.
And so that’s one of the big criticisms
of the doomsday argument.
But I do think it has a compelling point
that it would be surprising
if our future is to one day blossom
and become a galactic spanning empire,
trillions upon trillions upon trillions of human beings
will one day live across the stars
for essentially as long as the galaxy exists
and the stars burn.
We would live at an incredibly special point in that story.
We would be right at the very, very, very beginning.
And that’s not impossible,
but it’s just somewhat improbable.
And so part of that sort of irks against me,
but it also almost feels like a philosophical argument
because you’re sort of talking about
souls being drawn from this cosmic pool.
So it’s not an argument that I lose sleep about
for our fate of the doomsday,
but it is somewhat intellectually annoying
that there is a slight contradiction
now it feels like with the idea
of a galactic spanning empire.
Yeah, but of course there’s so many unknowns.
I for one would love to visit even space,
but Mars, just imagine standing on Mars
and looking back at Earth.
The incredible sight.
It would give you such a fresh perspective
as to your entire existence and what it meant to be human.
And then come back to Earth,
it would give you a heck of a perspective.
Plus the sunset on Mars is supposed to be nice.
I loved what William Shatner said after his flight.
His words really moved me when he came down.
And I think it really captured the idea
that we shouldn’t really be sending engineers
or scientists into space.
We should be sending our poets
because those are the people when they come down
who can truly make a difference
when they describe their experiences in space.
And I found it very moving reading what he said.
Yeah, when you talk to astronauts,
when they describe what they see, it’s like this,
like they discovered a whole new thing
that they can’t possibly convert back into words.
It’s beautiful to see.
Just as a quick, before I forget, I have to ask you,
can you summarize your argument against the hypothesis
that we live in a simulation?
Is it similar to our discussion about the Doomsday Clock?
No, it’s actually pretty more similar
to my agnosticism about life in the universe.
And it’s just sort of remaining agnostic
about all possibilities.
The simulation argument,
sometimes it gets mixed.
There’s kind of two distinct things that we need to consider.
One is the probability that we live in so-called base reality
that we’re not living in a simulated reality itself.
And another probability we need to consider
is the probability that that technology is viable,
possible, and something we will ultimately choose
to one day do.
And those are two distinct things.
They’re probably quite similar numbers to each other,
but they are distinct probabilities.
So in my paper I wrote about this,
I just tried to work through the problem.
I teach astrostatistics,
I was actually teaching it this morning.
And so it just seemed like a fun case study
of working through a Bayesian calculation for it.
Bayesian calculations work on conditionals.
And so when you hear,
what kind of inspired this project
was when I heard Musk said was like a billion to one chance
that we don’t live in a simulation.
He’s right if you add the Bayesian conditional,
and the Bayesian conditional is conditioned upon the fact
that we eventually develop that technology
and choose to use it,
or it’s chosen to be used by such species,
by such civilizations.
That’s the conditional.
And you have to add that in
because that conditional isn’t guaranteed.
And so in a Bayesian framework,
you can kind of make that explicit.
You see mathematically explicitly
that’s a conditional in your equation.
And the opposite side of the coin is basically
in the trilemma that Bostrom originally put forward
is options one and two.
So option one is that you basically never develop
the ability to do that.
Option two is you never choose to execute that.
So we kind of group those together
as sort of the non-simulation scenario, let’s call it.
And so you’ve got non-simulation scenario
and simulation scenario.
And agnostically, we really have to give the,
how do you assess the model,
the a priori model probability of those two scenarios?
It’s very difficult and we can,
I think people would probably argue
about how you assign those priors.
In the paper, we just assigned 50-50.
We just said, this hasn’t been demonstrated yet.
There’s no evidence that this
is actually technically possible,
but nor is it that it’s not technically possible.
So we’re just gonna assign 50-50 probability
to these two hypotheses.
And then in the hypothesis
where you have a simulated reality,
you have a base reality set at the top.
So there is, even in the simulated hypothesis,
there’s a probability you still live in base reality.
And then there’s a whole myriad of universes beneath that,
which are all simulated.
And so you have a very slim probability
of being in base reality if this is true.
And you have a 100% probability of living in base reality,
on the other hand, if it’s not true
and we never develop that ability
or choose never to use it.
And so then you apply this technique
called Bayesian model averaging,
which is where you propagate the uncertainty
of your two models to get a final estimate.
And because of that one base reality
that lives in the simulated scenario,
you end up counting this up
and getting that it always has to be less than 50%.
So the probability you live in a simulated reality
versus base reality has to be slightly less than 50%.
Now that really comes down to that statement
of giving it 50-50 odds to begin with.
And on the one hand, you might say,
look, David, I work in artificial intelligence,
I’m very confident that this is gonna happen,
just of extrapolating of current trends.
Or on the other hand, a statistician would say,
you’re giving way too much weight
to the simulation hypothesis
because it’s an intrinsically highly complicated model.
You have a whole hierarchy of realities
within realities within realities.
It’s like the Inception-style thing, right?
And so this requires hundreds, thousands,
millions of parameterizations to describe.
And by Occam’s razor, we would always normally penalize
inherently complicated models as being disfavored.
So I think you could argue I’m being too generous
or too kind with that.
But I sort of want to develop
the rigorous mathematical tools to explore it.
And ultimately, it’s up to you to decide
what you think that 50-50 odds should be.
But you can use my formula to plug in whatever you want
and get the answer, and I use 50-50.
So, and, but in that first pile,
with the first two parts that the bossman talks about,
it seems like connected to that
is the question we’ve been talking about,
which is the number of times at bat you get,
which is the number of intelligent civilizations
that are out there that can build such simulations.
That’s, it seems like very closely connected
because if we’re the only ones that are here
and can build such things, that changes things.
I mean, yeah, the simulation hypothesis
has all sorts of implications like that.
I’ve always loved, as Sean Carroll points out,
a really interesting contradiction, apparently,
with the simulation hypothesis
that I speak about a little bit in the paper.
But he showed that, or pointed out,
that in this hierarchy of realities,
which then develop their own AIs within the realities,
and then they, or really ancestor simulations,
I should say, rather than AI,
they develop their own capability to simulate realities.
You get this hierarchy,
and so eventually there’ll be a bottom layer,
which I often call the sewer of reality.
It’s like the worst layer where it’s the most pixelated
it could possibly be, right?
Because each layer is necessarily
going to have less computational power
than the layer above it.
Because not only are you simulating that entire planet,
but also some of that’s being used
for the computers themselves that those are simulated.
And so that base reality, or sorry,
the sewer of reality is a reality
where they are simply unable
to produce ancestor simulations
because the fidelity of the simulation is not sufficient.
And so from their point of view,
it might not be obvious that the universe is pixelated,
but they would just never be able
to manifest that capability.
What if they’re constantly simulating,
because in order to appreciate the limits of the fidelity,
you have to have an observer.
What if they’re always simulating
a dumber and dumber observer?
What if the sewer has very dumb observers that can’t,
like scientists that are the dumbest possible scientists.
So it’s very pixelated, but the scientists are too dumb
to even see the pixelations.
That’s like built into the universe
always has to be a limitation on the cognitive capabilities
of the complex systems that are within it.
Yeah, so that sewer of reality,
they would still presumably be able
to have a very impressive computational capabilities.
They’d probably be able to simulate galactic formation
or this kind of impressive stuff,
but they would be just short of the ability
to however you define it,
create a truly sentient conscious experience in a computer.
That would just be just beyond their capabilities.
And so Carol pointed out that if you add up all the,
you count up how many realities there should be,
probabilistically, if this is true,
over here, the simulation hypothesis or scenario,
then you’re most likely to find yourself in the sewer
because there’s just far more of them
than there are of any of the higher levels.
And so that sort of sets up a contradiction
because then you live in a reality
which is inherently incapable
of ever producing ancestor simulations.
But the premise of the entire argument
is that ancestor simulations are possible.
So there’s a contradiction that’s been introduced.
There’s that old quote, we’re all living in the sewer,
but some of us are looking up at the stars.
This is maybe more true than we think.
To me, so there’s of course physics
and computational fascinating questions here,
but to me, there’s a practical psychological question
which is how do you create a virtual reality world
that is as compelling,
and not necessarily even as realistic,
but almost as realistic,
but as compelling or more compelling than physical reality?
Because something tells me it’s not very difficult.
In the full history of human civilization,
that is an interesting kind of simulation to me
because that feels like it’s doable
in the next hundred years,
creating a world where we all prefer
to live in the digital world.
And not like a visit,
but like it’s like you’re seen as insane.
No, like you’re required.
It’s unsafe to live outside of the virtual world.
And it’s interesting to me from an engineering perspective
how to build that,
because I’m somebody that sort of loves video games
and it seems like you can create incredible worlds there
and stay there.
And it’s a different question
than creating a ultra high resolution,
high fidelity simulation of physics.
But if that world inside a video game
is as consistent as the physics of our reality,
then you can have your own scientists in that world
that trying to understand that physics world.
It might look different.
I’m presuming that eventually forget,
give it long enough,
they might forget about their origins
of being once biological
and assume this is their only reality.
Especially if you’re now born,
well, certainly if you’re born,
but even if you were eight years old or something
when you first started wearing the headset.
Yeah, or you have a memory wipe when you go in.
I mean, it also kind of maybe speaks to this issue
of like Neuralink and how do we keep up with AI in our world?
If you want to augment your intelligence,
perhaps one way of competing
and one of your impetuses for going into this digital reality
would be to be competitive intellectually
with artificial intelligences
that you could trivially augment your reality
if your brain was itself artificial.
But I mean, one skepticism I’ve always had about that
is whether it’s more of a philosophical question,
but how much is that really you if you do a mind upload?
Is this just a duplicate of your memories
that thinks it’s you versus truly a transference
of your conscious stream into that reality?
And I think when you,
it’s almost like the teleportation device in Star Trek,
but with teleportation, quantum teleportation,
you can kind of rigorously show that,
as long as all of the quantum numbers
are exactly duplicated as you transfer over,
it truly is from the universe’s perspective
in every way indistinguishable from what was there before.
It really is, in principle, you
and all the sense of being you
versus creating a duplicate clone
and uploading memories to that human body or a computer
that would surely be a discontinuation
of that conscious experience
by virtue of the fact you’ve multiplied it.
And so I would be hesitant about uploading for that reason.
I would see it mostly as my own killing myself
and having some AI duplicate of me
that persists in this world,
but is not truly my experience.
Typical 20th century human
with an attachment to this particular
singular instantiation of brain and body.
How silly humans used to be.
Used to have rotary phones and other silly things.
You’re an incredible human being.
You’re an educator, you’re a researcher.
You have an amazing YouTube channel.
Looking to young people, if you were to give them advice,
how can they have a career that maybe is inspired by yours,
inspired by wandering curiosity,
a career they can be proud of or a life they can be proud of?
What advice would you give?
I certainly think in terms of a career in science,
one thing that I maybe discovered late,
but has been incredibly influential on me
in terms of my own happiness and my own productivity
has been this synergy of doing two passions at once,
one passion in science communication
and another passion research
and not surrendering either one.
And I think that tends to be seen as something
that’s an either or.
You have to completely dedicate yourself to one thing
to gain mastery in it.
That’s a conventional way of thinking about both science
and other disciplines.
And I have found that both have been elevated
by practicing in each.
And I think that’s true in all assets of life.
I mean, if you want to become the best researcher
you possibly can, you’re pushing your intellect
and in a sense your body to a high level.
And so to me, I’ve always wanted to couple that
with training of my body, training of my mind
and other ways besides from just what I’m doing
when I’m in the lecture room or when I’m in my office,
you know, calculating something.
Focusing on your own development
through whatever it is, meditation,
for me it’s often running, working out
and pursuing multiple passions
provides this almost synergistic bliss
of all of them together.
So often I’ve had some of the best research ideas
from making a YouTube video and trying to communicate an idea
or interacting with my audience
who’ve had a question that sparked a whole trail of thought
that led down this wonderful intellectual rabbit hole
or maybe to a new intellectual discovery
can go either way sometimes with those things.
And so thinking broadly, diversely
and always looking after yourself
in this highly competitive
and often extremely stressful world that we live in
is the best advice I can offer anybody
and just try, if you can, it’s very cheesy
but if you can follow your passions, you’ll always be happy.
Trying to sell out for the quick cash out,
for the quick book out can be tempting in the short term.
Looking for exomoons was never easy
but I made a career not out of discovering exomoons
but out of learning how to communicate
the difficult problem
and discovering all sorts of things along the way.
We shot for the sky
and we discovered all this stuff along the way.
We discovered dozens of new planets
using all sorts of new techniques.
We pushed this instrumentation to new places
and I’ve had an extremely productive research career
in this world.
I’ve had all sorts of ideas working on techno signatures.
It’s, you know, thinking innovatively pushes you
into all sorts of exciting directions.
So just try to, yeah, it’s hard to find that passion
but you can sometimes remember it when you were a kid,
what your passions were
and what fascinated you as a child.
For me, as soon as I picked up a space book
when I was five years old, that was it.
I was hooked on space
and I almost betrayed my passion at college.
I studied physics,
which I’ve always been fascinated by physics as well.
But I came back to astronomy because it was my first love
and I was much happier doing research in astronomy
than I was in physics
because it spoke to that wonder I had as a child
that first was the spark of curiosity for me in science.
So society will try to get you to look at hot Jupiters
and the advice is to look for the cool worlds instead.
What do you think is the meaning of this whole thing?
Have you ever asked yourself why?
It’s just a ride.
That’s how I think it.
It’s just a ride, we’re on a roller coaster
and we have no purpose.
It’s an accident in my perspective.
There’s no meaning to my life.
There’s no objective deity
who is overwatching what I’m doing
and I have some fate or destiny.
It’s all just riding on a roller coaster
and trying to have a good time
and contribute to other people’s enjoyment of the ride.
Yeah, try to make it a happy accident.
Yeah, yeah, I see no fundamental providence in my life
or in the nature of the universe.
And you just see this universe
as this beautiful cosmic accident
of galaxies smashing together,
stars forging here and there
and planets occasionally spawning maybe life
across the universe.
And we are just one of those instantiations
and we should just enjoy this very brief episode
that we have.
And I think trying to look at it much deeper than that
is to me, it’s not very soul satisfying.
I just think enjoy what you’ve got and appreciate it.
It does seem noticing that beauty
helps make the ride pretty fun.
David, you’re an incredible person.
I haven’t covered most of the things
I wanted to talk to you about.
This was an incredible conversation.
I’m glad you exist.
I’m glad you’re doing everything you’re doing
and I’m a huge fan.
Thank you so much for talking today.
This was amazing.
Thank you so much, Lex.
It’s a real honor, thank you.
Thanks for listening to this conversation
with David Kipping.
To support this podcast,
please check out our sponsors in the description.
And now let me leave you with some words from Carl Sagan.
Perhaps the aliens are here,
but are hiding because of some Lex Galactica,
some ethic of non-interference with emerging civilizations.
We can imagine them, curious and dispassionate,
observing us as we would watch a bacterial culture
in a dish to determine whether this year,
again, we managed to avoid self-destruction.
Thank you for listening and hope to see you next time.