But this is an illusion.

但這只是一種幻覺。

Just a small fraction of all atoms are found in galaxies, while the rest is thought to be drifting in between, in the intergalactic medium.

所有原子中只有一小部分存在於星系中，其餘的被認為漂浮在星系間介質中。

Like the roots of some massive tree, gas spreads out from each galaxy, gravity funneling fresh mass into this dense, cosmic forest.

就像一棵大樹的樹根一樣，氣體從每一個星系中擴散出來，引力把新的物質輸送到這片茂密的宇宙森林中。

Here, in the intergalactic medium, are the raw materials of creation.

在這裡，在星際介質中，有創造的原材料。

Hydrogen and helium, woven into sheets and filaments that flow into galaxies where they eventually create stars.

氫和氦交織成片狀和絲狀，流入星系，最終形成恆星。

But if we look closely, we see who's actually in charge.

但如果我們仔細觀察，就會發現誰才是真正的負責人。

Quasars, the single most powerful objects in existence.

類星體，現存最強大的天體。

As small as a grain of sand compared to the Amazon River, they reside in the centers of some galaxies, shining with the power of a trillion stars, blasting out huge jets of matter, completely reshaping the cosmos around them.

與亞馬遜河相比，它們就像一粒沙子那麼小，但它們卻居住在一些星系的中心，閃耀著萬億顆恆星的光芒，噴射出巨大的物質流，完全重塑了周圍的宇宙。

They're so powerful that they can kill a galaxy.

它們如此強大，可以殺死一個星系。

What are they, and how do they mold the structure of the universe at their whim?

它們是什麼？它們是如何隨心所欲地塑造宇宙結構的？

Everywhere you look, weird things in the sky.

天空中到處都是奇怪的東西。

In the 1950s, astronomers noticed mysterious loud radio waves coming from spots all over the sky.

20 世紀 50 年代，天文學家注意到天空中到處都有神祕的巨大無線電波。

They were named quasi-stellar radio sources, or quasars, because they were dots like stars, but were seen in radio waves rather than visible light.

它們被命名為準恆星射電源，或類星體，因為它們是像恆星一樣的小點，但看到的是無線電波而不是可見光。

Everything about them was strange.

他們的一切都很奇怪。

Some flickered, others emitted high-energy X-rays in addition to radio waves, but all seemed to be tiny.

有的在閃爍，有的除了無線電波外還發出高能 X 射線，但似乎都很小。

They all moved extremely fast, as much as over 30% the speed of light.

它們的移動速度都非常快，超過了光速的 30%。

The only explanation was that they must have been so distant that their apparent speed was actually the expansion of the universe moving them away from us.

唯一的解釋是，它們一定非常遙遠，以至於它們表面上的速度實際上是宇宙的膨脹使它們遠離了我們。

But these enormous distances meant that quasars couldn't just be stars, but the active cores of galaxies billions of light-years away.

但是，這些巨大的距離意味著類星體不可能只是恆星，而是數十億光年之外星系的活動核心。

And it gets crazier.

而且越來越瘋狂。

To appear so bright and loud, given these vast distances, they are thousands of times brighter than the entire Milky Way.

在如此遙遠的距離上，它們顯得如此明亮和響亮，其亮度是整個銀河系的數千倍。

Monsters exploding and screaming into the void with a violence not thought possible before.

怪物在虛空中爆炸和尖叫，其暴力程度前所未見。

As we mapped the sky, we discovered over a million quasars.

在繪製天空地圖的過程中，我們發現了一百多萬個類星體。

And they all seemed to be very far away.

他們似乎都離得很遠。

Looking into space far away means very long ago, because light takes so long to reach us.

遙望太空意味著很久很久以前，因為光到達我們這裡需要很長時間。

Quasars were common in the early universe, having peaked in number 10 billion years ago, when galaxies and the universe itself were still very young.

類星體在宇宙早期非常常見，在 100 億年前達到頂峰，當時星系和宇宙本身都還非常年輕。

Let's go back in time, just 3 billion years after the Big Bang, and see what was going on back then.

讓我們回到宇宙大爆炸後的 30 億年，看看那時發生了什麼。

How could an early baby galaxy be so incredibly bright and violent?

一個早期的嬰兒星系怎麼會如此明亮和狂暴呢？

All that light and radiation couldn't be stars, as there weren't nearly enough of them.

所有的光和輻射都不可能是恆星，因為它們的數量遠遠不夠。

And since galaxies tend to grow with time by emerging, the starlight from small galaxies shouldn't be far brighter than any galaxy today.

而且，由於星系往往會隨著時間的推移而不斷出現，小星系發出的星光應該不會比現在的任何星系亮得多。

There's only one way to generate the vast amounts of energy a quasar shines with.

只有一種方法可以產生類星體閃耀的巨大能量。

Feeding supermassive black holes.

餵養超大品質黑洞

We still don't know how exactly they formed, but it seems that every galaxy has one in their center.

我們仍然不知道它們究竟是如何形成的，但似乎每個星系的中心都有一個。

But how can the brightest things in the universe be black holes, which trap anything and everything that crosses their event horizon?

但是，宇宙中最亮的東西怎麼會是黑洞呢？黑洞會困住穿過其事件視界的任何事物。

Well, the light of a quasar is not coming from inside these black holes.

那麼，類星體的光線並非來自這些黑洞內部。

Rather, it comes from the space around them, a massive orbiting disk of gas called an attrition disk.

相反，它來自它們周圍的空間，一個巨大的軌道氣體盤，稱為損耗盤。

Quasars use the same fuel as stars to shine.

類星體使用與恆星相同的燃料發光。

Matter.

事項。

It's just that black holes are the most efficient engines for converting matter into energy in the universe.

只是黑洞是宇宙中最有效的將物質轉化為能量的引擎。

The energy released by matter falling into a black hole can be 60 times greater than that released by nuclear fusion in the core of a star, because the energy released by a black hole comes from gravity, not from nuclear reactions.

物質墜入黑洞所釋放的能量可能是恆星核心核聚變所釋放能量的 60 倍，因為黑洞釋放的能量來自重力，而不是核反應。

Matter falling into a black hole speeds up to almost the speed of light before it crosses the event horizon, buzzing with an incredible amount of kinetic energy.

落入黑洞的物質在穿過事件穹界之前，速度幾乎達到光速，迸發出驚人的動能。

Of course, once inside the black hole, it takes that energy with it.

當然，一旦進入黑洞，它就會帶走這些能量。

You only get to witness this energy if you drop your matter in the right way.

只有以正確的方式丟棄物質，你才能見證這種能量。

Fall straight down, and the outside universe gets nothing.

直接墜落，外部宇宙什麼也得不到。

But when you have a lot of matter, it spirals in incredibly fast towards the event horizon, forming a disk.

但是，當你擁有大量物質時，它們會以驚人的速度向事件穹界飛去，形成一個圓盤。

Collisions between particles and friction heat it up to hundreds of thousands of degrees.

粒子之間的碰撞和摩擦會將其加熱到數十萬度。

In a space not much bigger than our solar system, the core of a galaxy can release many times more energy than all its stars combined.

在一個比太陽系大不了多少的空間裡，一個星系的核心所釋放的能量比所有恆星加起來還要多好幾倍。

This is what a quasar is.

這就是類星體。

A supermassive black hole having a feast.

超大品質黑洞的盛宴

And these black holes eat a lot.

這些黑洞的食量很大。

Typical quasars consume one to a hundred Earth masses of gas per minute.

典型的類星體每分鐘消耗 1 到 100 個地球品質的氣體。

Ten billion years ago, the universe was about a third of its current size, so the intergalactic medium was much less spread out, meaning the filaments of gas around quasars could feed them a banquet, making them vomit insane amounts of light and radiation.

100 億年前，宇宙的大小約為現在的三分之一，是以星系間介質的分佈要少得多，這意味著類星體周圍的氣體絲可以為它們提供盛宴，讓它們吐出大量的光和輻射。

The brightest quasars power jets, tangling the magnetic field of the matter around them into a narrow cone.

最亮的類星體會產生噴流，將周圍物質的磁場纏繞成一個狹窄的錐體。

Like a particle accelerator, they launch enormous beams of matter out, plowing through the circumgalactic medium, forming plumes of matter that grow to hundreds of thousands of light-years in size.

它們就像粒子加速器一樣，發射出巨大的物質束，穿過環銀河介質，形成物質羽流，其大小可達數十萬光年。

It's almost unfathomable in scale.

它的規模幾乎深不可測。

A tiny spot in a galaxy carving out patches of the universe hundreds of thousands of light-years long.

銀河系中的一個小點，劃出了數十萬光年長的宇宙斑塊。

But quasars can't eat for long, maybe a few million years, because their feast ultimately kills their galaxy.

但是類星體不能長期進食，也許只有幾百萬年，因為它們的盛宴最終會殺死它們的星系。

Okay, maybe killing is a bit of an exaggeration.

好吧，也許殺戮有點誇張。

A galaxy is still there after its quasar turns off, but it will never be the same again.

一個星系在類星體關閉後依然存在，但它再也不會是原來的樣子了。

Quasars, being among the hottest and brightest things in the universe, break their galaxies by heating them up too much and stopping star formation.

類星體是宇宙中最熾熱、最明亮的物體之一，會使星系溫度過高，停止恆星的形成，從而使星系破碎。

Stars are gas that collapsed in on itself and then got really hot.

恆星是塌縮在一起的氣體，然後變得非常熱。

But in a cloud of gas that's already hot, atoms are moving quickly.

但在一團已經很熱的氣體雲中，原子正在快速移動。

When they collide, they hit hard, exerting pressure that resists gravity's squeeze.

當它們相撞時，會產生巨大的衝擊力，從而抵禦地心引力的擠壓。

So hot gas cannot form stars.

是以，高溫氣體無法形成恆星。

Instead, the best gas for forming stars is already cold and won't put up a fight when it's time to collapse into a star.

相反，最適合形成恆星的氣體已經很冷了，當它要坍縮成恆星時，就不會再反抗了。

On top of that, quasars push gas out of their galaxies.

除此之外，類星體還會把氣體擠出星系。

Not only does this starve the quasar, but its galaxy loses the raw materials for new stars.

這不僅使類星體陷入飢餓，而且它所在的星系也失去了製造新恆星的原材料。

As sad as this sounds, it might be a good thing for life.

雖然這聽起來很悲傷，但對生活來說也許是件好事。

The alternative can be far more dangerous. Too many stars.

另一種選擇可能更危險。星星太多

New stars forming is usually followed by massive stars exploding in supernovae, so planets would be burned sterile.

新恆星形成後，大品質恆星通常會在超新星中爆炸，是以行星會被燒燬而失去生育能力。

But of course, it's more complicated.

當然，情況更為複雜。

Like the intricacies of our own planet's biosphere, every piece of the galaxy is dependent on and influencing every other part of the galactic environment.

就像我們地球上錯綜複雜的生物圈一樣，銀河系的每一個部分都依賴並影響著銀河系環境的每一個其他部分。

While hot things like quasars and supernovae tend to push gas out of the galaxy, shockwaves and quasar jets can also compress gas, making new stars at least for a short time.

類星體和超新星等高溫物質往往會把氣體擠出星系，但衝擊波和類星體噴流也會壓縮氣體，至少在短時間內製造出新的恆星。

But in general, we can say that without things becoming a bit more chill, we would not exist today.

但總的來說，我們可以說，如果沒有變得更加冷酷的事物，就不會有今天的我們。

Which brings us to our final question.

這就引出了我們的最後一個問題。

Did the Milky Way have a quasar in the past?

銀河系過去有類星體嗎？

It's unclear if every galaxy went through a quasar phase, but understanding distant quasars may provide clues to the history of the Milky Way.

目前還不清楚是否每個星系都經歷過類星體階段，但瞭解遙遠的類星體可能會為銀河系的歷史提供線索。

Galaxies don't do a good job of preserving their history.

星系並沒有很好地保存它們的歷史。

Like sand on a beach, the endless churning mixes away the clues to their past.

就像沙灘上的沙子一樣，無休止的攪動混雜著他們過去的線索。

It's possible the Milky Way was once a quasar, which may have allowed our supermassive black hole Sagittarius A star to have grown to 4 million times the mass of the Sun.

銀河系可能曾經是一個類星體，這可能使我們的超大品質黑洞人馬座 A 星的品質增長到了太陽品質的 400 萬倍。

And as dormant as it is now, Sagittarius A star could turn into a quasar in the future.

儘管人馬座 A 星現在處於休眠狀態，但它將來可能會變成一顆類星體。

In a few billion years, the Milky Way will merge with Andromeda.

再過幾十億年，銀河系將與仙女座合併。

We've seen over a hundred double quasars in galaxies smashing together, where fresh gas is provided for the central black holes.

我們已經在星系中看到了一百多個撞擊在一起的雙類星體，它們為中心黑洞提供了新鮮氣體。

But it won't last for long.

但這不會持續太久。

When galaxies merge, so do their supermassive black holes, sinking into the center of their new galaxy, kicking up dust and stars in every direction.

星系合併時，它們的超大品質黑洞也會沉入新星系的中心，將塵埃和恆星拋向四面八方。

We don't know whether this will happen, but it would truly be an incredible sight.

我們不知道這是否會發生，但這確實是一個令人難以置信的景象。

Maybe some beings in the far future are going to witness it and be in awe of what they see.

也許在遙遠的未來，有些人會親眼目睹這一切，並對所看到的一切感到敬畏。

But you don't have to wait that long.

但你不必等那麼久。

There are already plenty of fascinating things to explore, right here on this planet, right now, if you have the knowledge to understand them.

就在這個星球上，就在此時此刻，如果你有足夠的知識去了解它們，已經有很多迷人的事物值得你去探索。

To help you with that, we've created a series of lessons to take your scientific knowledge to the next level.

為此，我們開設了一系列課程，讓您的科學知識更上一層樓。

Made in collaboration with our friends at Brilliant.org, these lessons give you a deeper understanding of the topics from our most popular videos, from rabies and mammalian metabolism to climate science.

這些課程是與我們在 Brilliant.org 的朋友合作製作的，讓您更深入地瞭解我們最受歡迎視頻中的主題，從狂犬病、哺乳動物新陳代謝到氣候科學。

There's also a lesson on black holes, where you can delve into the fundamental principles behind their formation and behavior.

還有一堂關於黑洞的課，你可以深入瞭解黑洞形成和行為背後的基本原理。

A deeper understanding will also help you appreciate their role in powering the quasars we talked about in this video.

更深入的瞭解還有助於你理解它們在為我們在本視頻中談到的類星體提供動力方面所起的作用。

Brilliant is an interactive learning tool that makes maths, science, and computer science accessible with a hands-on approach.

Brilliant 是一種互動學習工具，它通過動手操作的方式讓數學、科學和計算機科學變得觸手可及。

Because we know that to really learn something, you've got to do it.

因為我們知道，要真正學到東西，就必須去做。

Think of each lesson as a one-on-one tutoring version of a Kurzgesagt video.

將每節課視為一對一輔導版的 Kurzgesagt 視頻。

Brilliant has thousands of other lessons to explore as well.

Brilliant 還有數以千計的其他課程可供探索。

From maths-based topics like algebra and probability to courses around programming and data science.

從代數和概率等數學主題到編程和數據科學課程，應有盡有。

Their latest course, How Technology Works, takes you inside the technology you use every day.

他們的最新課程 "技術如何工作 "將帶您瞭解您每天使用的技術。

You'll walk in the footsteps of a hacker to discover why some passwords take decades to crack, explore how satellites in space know that your rideshare driver is just down the street, learn why your favorite Kurzgesagt video might buffer on YouTube, and more.

您將追隨黑客的腳步，發現為什麼有些密碼需要幾十年才能破解，探索太空中的衛星如何知道您的共享司機就在街邊，瞭解為什麼您最喜歡的 Kurzgesagt 視頻可能會在 YouTube 上緩衝，等等。

To get hands-on with Kurzgesagt's lessons and explore everything Brilliant has to offer, you can start your free 30-day trial by signing up at brilliant.org.

要親身體驗 Kurzgesagt 的課程並探索 Brilliant 提供的一切，您可以在 brilliant.org 上註冊，開始為期 30 天的免費試用。

There's even an extra perk for Kurzgesagt viewers.

Kurzgesagt 的觀眾甚至還有額外的福利。

The first 200 people to use the link get 20% off an annual membership once their trial ends.

試用期結束後，前 200 名使用該鏈接的用戶可享受年度會籍八折優惠。

We love seeing how the gears interlock with our research.

我們喜歡看到齒輪是如何與我們的研究相互關聯的。

Brilliant gives you the tools to understand how everything fits together.

Brilliant 為您提供工具，讓您瞭解一切是如何結合在一起的。

www.brilliant.org

www.brilliant.org