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中子星喺宇宙之中一種極端而又狂野嘅星體 Neutron stars are one of the most extreme and violent things in the universe.

似粒巨型原子 直徑只有幾百公里 Giant atomic nuclei, only a few kilometers in diameter,

但質量可以同行星相比 but as massive as stars.

佢地嘅誕生歸功於的星體壯麗嘅死亡 And they owe their existence to the death of something majestic.

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行星內有種脆弱嘅平衡 Stars exist because of a fragile balance.

數億億億噸熱等離子 The mass of millions of billions of trillions of tons of hot plasma

被重力拉向星體中心 are being pulled inwards by gravity,

物質被不斷擠壓 and squeeze material together with so much force

直到出現核融合 that nuclei fuse.

氫原子融合產生氦原子 Hydrogen fuses into helium.

過程中釋放巨大嘅能量 This releases energy,

抵銷重力嘅擠壓 並且發出輻射 which pushes against gravity and tries to escape.

只要這種平衡存在，行星就會保持穩定 As long as this balance exists, stars are pretty stable.

直到氫原子會被耗盡 Eventually, the hydrogen will be exhausted.

好似太陽咁嘅中型行星會變成紅巨星 Medium stars, like our Sun, go through a giant phase,

氦原子融合產生碳原子同氧原子 where they burn helium into carbon and oxygen

最終紅巨星變成白矮星 before they eventually turn into white dwarfs.

但係比太陽重得多的星體 But in stars many times the mass of our Sun,

當氫原子被耗盡，事情就更加有趣 things get interesting when the helium is exhausted.

有時 For a moment,

重力同輻射嘅平衡中 the balance of pressure and radiation tips,

重力較強 and gravity wins,

星體被壓縮 squeezing the star tighter than before.

令核心燒得更熱更快 The core burns hotter and faster,

星體外層膨脹幾千倍 while the outer layers of the star swell by hundreds of times,

越來越重嘅元素被燃燒 fusing heavier and heavier elements.

在幾百年中，碳融合產生氖 Carbon burns to neon in centuries,

一年內，氖融合成氧 neon to oxygen in a year,

幾個月內，氧融合變矽 oxygen to silicon in months,

一日內，矽變鐵 and silicon to iron in a day.

突然， And then…

死亡。 …death.

鐵係核融合嘅灰燼 Iron is nuclear ash.

鐵融合無得釋放能量 It has no energy to give and cannot be fused.

融合突然停止，重力勝利 :( The fusion suddenly stops, and the balance ends :(

無咗由核融合產生嘅向外輻射壓， Without the outward pressure from fusion,

巨大嘅恆星外殼重重地向核心塌縮 the core is crushed by the enormous weight of the star above it.

驚嘆又恐怖。 What happens now is awesome and scary.

電子質子之類嘅粒子 Particles, like electrons and protons,

唔係好中意黐埋一齊 really don’t want to be near each other.

但塌縮嘅壓力十分巨大 But the pressure of the collapsing star is so great

質子電子融合變成中子(電子捕獲) that electrons and protons fuse into neutrons,

中子緊緊地擠埋一齊好似咁原子核咁 which then get squeezed together as tightly as in atomic nuclei.

一個地球大小嘅鐵球 An iron ball, the size of the Earth,

被壓成一粒城市太小嘅原子核 is squeezed into a ball of pure nuclear matter, the size of a city.

唔止星體核心， But not just the core;

整個星體內爆 the whole star implodes,

外層被重力以光速嘅四分一拉向中心 gravity pulling the outer layers in at 25% the speed of light.

物質撞擊鐵核心並反彈 This implosion bounces off the iron core,

產生向外嘅衝激波 producing a shock wave that explodes outwards

部分嘅質量射咗出太空 and catapults the rest of the star into space.

呢個就係 超新星爆炸 This is what we call a supernova explosion,

強度足以照耀整個星系 and it will outshine entire galaxies.

而家，恆星剩低嘅就係叫中子星 What remains of the star is now a neutron star.

佢嘅質量係地球嘅幾百萬倍 Its mass is around a million times the mass of the Earth

不過，被壓縮到大約25公里嘅大小 but compressed to an object about 25 kilometers wide.

緻密嘅程度就好似將全人類嘅質量 It’s so dense that the mass of all living humans

壓縮到幾厘米嘅正方體 [好恐怖] would fit into one cubic centimeter of neutron star matter.

呢粒方糖大小嘅東東 That’s roughly a billion tons

大約有十億頓重 in a space the size of a sugar cube.

換種講法， Put another way,

就係擺珠穆朗瑪峰落個咖啡杯度 that’s Mount Everest in a cup of coffee.

從外面嚟睇，中子星係難以想像嘅極端。 From the outside, a neutron star is unbelievably extreme.

佢重力嘅強度僅次於黑洞 Its gravity is the strongest, outside black holes,

如果密度再高少少，就會變成黑洞 and, if it were any denser, it would become one.

周圍嘅光線會被折曲 Light is bent around it,

即係話你會見到佢正面同佢遮住咗嘅野 meaning you can see the front and parts of the back.

表面溫度高達一百萬度 Their surfaces reach 1,000,000 degrees Celsius,

而太陽僅僅只有 6000 度 compared to a measly 6,000 degrees for our Sun.

好。睇幾中子星入面 Okay, let’s look inside a neutron star.

雖然佢地係成粒恆星咁大嘅巨型原子核， Although these giant atomic nuclei are stars,

佢地某程度又似擁有 in many ways, they’re also like planets,

固態外殼同液態核心嘅行星 with solid crusts over a liquid core.

外殼十分堅硬 The crust is extremely hard.

最外層由超新星爆炸後剩低嘅鐵組成 The outermost layers are made of iron left over from the supernova,

呈現晶體結構 squeezed together in a crystal lattice,

電子係原子核間流動 with a sea of electrons flowing through them.

不斷深入，原子核比重力擠壓得更緊密 Going deeper, gravity squeezes nuclei closer together.

質子變得越來越少 We find fewer and fewer protons,

因為同電子合併咗做中子 as most merge to neutrons

到外殼嘅底層 until we reach the base of the crust.

係呢度，原子核被擠壓得 Here, nuclei are squeezed together so hard

可以互相接觸 that they start to touch.

質子同中子重新排列 Protons and neutrons rearrange,

成圓筒/薄板狀 making long cylinders or sheets,

數以百萬計質子同中子組成嘅巨型嘅原子核 enormous nuclei with millions of protons and neutrons

形狀就好似意粉同千層麵 shaped like spaghetti and lasagna,

物理學家叫做核子意粉(nuclear pasta) [唔識中文] which physicists call nuclear pasta.

Nuclear pasta 好可能係宇宙中嘅最強物質 Nuclear pasta is so dense that it may be the strongest material in the universe,

堅不可摧 basically unbreakable.

中子星內嘅核子麵團 Lumps of pasta inside a neutron star

構成嘅山脈 can even make mountains

得幾厘粒高嘅 at most a few centimeters high,

但足足有喜馬拉雅山咁重 but many times as massive as the Himalayas.

係呢啲意粉下面 Eventually, beneath the pasta,

我地到達中子星嘅核心 we reach the core.

目前核心物質嘅特性仲唔係好清楚 We’re not really sure what the properties of matter are

當佢地處於咁硬淨嘅狀態 when they’re squeezed this hard.

質子同中子可能熔解成夸克海 Protons and neutrons might dissolve into an ocean of quarks,

叫做 夸克-膠子等離子體 a so-called quark-gluon plasma.

有啲夸克可能變成 奇夸克 Some of those quarks might turn into strange quarks,

組成奇異物質 making a sort of strange matter,

擁有極端嘅特性 with properties so extreme,

我地有一條關於佢嘅片 that we made a whole video about it.

又或者佢地會保持係質子同中子狀態 Or maybe they just stay protons and neutrons.

真相無人知曉 No one knows for sure,

所以先會有科學 and that’s why we do science.

呢啲都係好沉重嘅野 That’s all pretty heavy stuff,

真係好重。 literally.

睇返係太空嘅視角 So let’s go back out into space.

當中子星形成， (超新星塌縮) When neutron stars first collapse,

佢開始自轉，好快咁轉 they begin to spin very, very fast,

好似芭蕾舞者縮埋雙手 (外殼撞向核心) like a ballerina pulling her arms in.

中子星係天空上嘅芭蕾舞者 Neutron stars are celestial ballerinas,

每秒轉好多次 spinning many times per second.

造成脈衝 This creates pulses

因為佢地嘅磁場產生一束無線電波 because their magnetic field creates a beam of radio waves,

每轉一圈就有一個信號 which passes every time they spin.

脈衝星 These radio pulsars

係種好出名嘅中子星 are the best-known type of neutron star.

係銀河系入面就有 2000 個已知嘅脈衝星 About 2,000 are known of in the Milky Way.

有啲中子星嘅磁場係宇宙最強 These magnetic fields are the strongest in the universe,

比地球磁場強 1000000000000000 倍 a quadrillion times stronger than Earth’s after they’re born.

佢地叫做 磁星 They’re called magnetars

直到磁場减弱 until they calm down a little.

而最出名嘅中子星類型 But the absolute best kind of neutron stars

係中子星雙星 are friends with other neutron stars.

以重力波形式釋放能量 By radiating away energy as gravitational waves,

係時空中造成漣漪 ripples in spacetime,

佢地嘅軌距會衰減 their orbits can decay,

然後撞埋一齊，同歸終盡。 and they can crash into and kill each other

叫做 千新星爆炸 in a kilonova explosion

噴出巨量物質 that spews out a lot of their guts.

合併時，環境十分極端 When they do, the conditions become so extreme

有更重嘅原子核產生 that, for a moment, heavy nuclei are made again.

今次唔係核融合將原子核黐埋一齊 It’s not fusion putting nuclei together this time,

而係重得嚟又有豐富中子嘅物質 (核子意粉) but heavy neutron-rich matter

撞散嘅同時又重組 falling apart and reassembling.

最近， Only very recently,

我地估計，呢個爆炸可能係宇宙之中較重元素嘅來源 we’ve learned that this is probably the origin of most of the heavy elements in the universe,

例如黃金、鈾同鉑 like gold, uranium, and platinum,

等等 and dozens more.

而家 So there now

兩粒中子星撞埋一齊變成一個黑洞 two neutron stars collapse and become a black hole,

再死一次。 dying yet again.

恆星必需死亡先可以產生更重嘅元素 Not only do stars have to die to create elements,

而且要死兩次 they have to die twice.

經過幾百萬年， Over millions of years,

呢啲新原子會混合至星系之中 these atoms will mix back into the galaxy,

部分會組成星雲 but some of them end up in a cloud,

重力拉埋佢地一齊組成新嘅星體 which gravity pulls together to form stars and planets,

再重複這循環 repeating the cycle.

太陽系就係一個例子， Our solar system is one example,

以前中子星嘅殘骸 and the remains of those neutron stars that came before us

就係我地身邊 are all around us.

現代化嘅科技世界 Our entire technological modern world

建立於係中子星死亡後產生嘅元素 was built out of the elements neutron stars made

係好耐好耐以前 in eons past,

呢啲原子經過 130 億年嘅旅程 sending these atoms on a thirteen-billion-year journey

聚埋一齊 我地同地球因而誕生 to come together and make us and our world.

正。 And that’s pretty cool.

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