本集简介
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以下是与理论物理学家兼宇宙学家詹娜·莱文的对话，她专长于黑洞、额外维度的宇宙学、宇宙的拓扑结构以及时空中的引力波。
The following is a conversation with Jenna Levin, a theoretical physicist and cosmologist specializing in black holes, cosmology of extra dimensions, topology of the universe, and gravitational waves in space time.
她还撰写了一些令人惊叹的书籍，包括《宇宙的斑点》（探讨宇宙的形状与大小）、《疯子梦想着巡游机器》（探讨天才、疯狂与知识的极限）、《黑洞蓝调及其他太空之歌》（关于LIGO和引力波的探测），以及《黑洞生存指南》（全面介绍黑洞）。
She has also written some incredible books, including how the universe got its spots on the topic of the shape and the size of the universe, a madman dreams of touring machines on the topic of genius, madness, and the limits of knowledge, black hole blues, and other songs from outer space, on the topic of LIGO and the detection of gravitational waves, and black hole survival guide, all about black holes.
这是一场有趣而引人入胜的对话。
This was a fun and fascinating conversation.
现在简要提及每一位赞助商。
And now a quick few second mention of each sponsor.
请在描述中查看他们。
Check them out in the description.
这是支持本播客的最佳方式。
It's the best way to support this podcast.
我们有Brain FM帮助专注，Better Health关注心理健康，NetSuite助力企业运营，Shopify助你销售商品，以及AG one呵护你的健康。
We've got Brain FM for focus, Better Health for mental health, NetSuite for your business, Shopify for selling stuff, and AG one for your health.
朋友们，请明智选择。
Choose wisely, my friends.
我通常在开头做较长的广告朗读。
I do these longer ad reads up in the beginning.
我努力让它们有趣，但同时也通过屏幕和描述中的时间戳让观众可以轻松跳过。
I try to make them interesting, but I do also make it super easy to skip with time stamps on screen and in the description.
不过，我会尽量让它们更具个人色彩，常常与我正在阅读或思考的内容相关。
I do, however, try to make them personal, often related to stuff I'm reading or thinking about.
另外，如果你有任何原因想联系我，请访问 lextreatment.com/contact。
Also, if you wanna get in touch with me for whatever reason, go to lextreatment.com/contact.
现在，进入完整的广告朗读部分。
And now, onto the full ad reads.
我们开始吧。
Let's go.
本集由 Brain FM 赞助，这是一个提供专为专注设计的音乐的平台。
This episode is brought to you by brain.fm, a platform that offers music specially made for focus.
当我提到音乐时，我指的是音频体验。
And when I say music, I mean audio experience.
如果你在外界见到我，比如在星巴克，我通常要么在专心写作，要么戴着耳机深度编程。
If you ever see me out in the wild, like a Starbucks, I'm usually either writing or programming deeply in focus with headphones.
耳机里播放着多层次的音频，混合了白噪音、节奏、雨声等多种元素。
In those headphones are layers of audio, a mixture of some noise, beats, rain, layers.
许多层次的音频帮助我深度、深度、深度地集中注意力。
Many layers that help me deeply, deeply, deeply focus.
说到音频，你知道罗马帝国曾用同步的战鼓来协调军团吗？
Speaking of audio, did you know that the Roman Empire used synchronized war drums to coordinate legions?
想象一下那些战鼓的声音。
Just imagine the sound of those drums.
我需要制作更多关于古罗马、古希腊和古中国的节目。
I need to do a lot more episodes on ancient Rome, on ancient Greece, on ancient China.
总之，现在在听战鼓声。
Anyway, now listening to war drums.
我正在听Brain FM，但我的注意力非常集中。
I'm listening to Brain f m, but I'm focusing.
你也可以通过访问 brain.fm/lex 来提升专注力，并免费试用 Brain.fm 三十天，那就是 brain.fm/lex，免费三十天。
You too can increase your focus and try brain.fm free for thirty days by going to brain.fm/lex, that's brain.fm/lex for thirty days free.
本集节目还由 BetterHelp 赞助，拼写为 h-e-l-p，即 help。
This episode is also brought to you by BetterHelp, spelled h e l p, help.
外面正在下雨，雷雨交加，就像有人在敲窗户。
It's raining outside, thunderstorms, like somebody's knocking on the window.
如果这还不是对潜意识的催促，那我不知道什么才是。
If that's not a metaphor for prodding the subconscious mind, I don't know what is.
艾伦·图灵在这集中被提及。
Alan Turing comes up in this episode.
他在二战期间的密码破译工作中发挥了关键作用。
He was crucial in the whole code breaking effort in World War two.
我应该做一个关于他的专题节目。
I should probably do an episode on that.
他的工作、他本人、他的思想一直是我生命中的一种存在。
His work, his person, his mind has been a presence in my life.
多么了不起的人啊。
What an incredible human being.
但无论如何，我认为人类的心灵，意识与潜意识，就像一种代码，而心理治疗则是一种破译过程。
But anyway, I think of the human mind, the conscious and the subconscious is a kind of code and therapy is a kind of code breaking process.
我不禁想，人工智能能否在这方面提供帮助，不只是基础的心理治疗，而是深度个性化治疗。
I wonder if AI will be able to help with that, not just basic therapy, but ultra deep personalized therapy.
天啊，那将是一个危险的世界。
Boy, that's a dangerous world.
无论如何，请访问 betterhelp.com/lex 体验我们的心理咨询师，并在第一个月享受优惠。
Anyway, check out our human therapist at betterhelp.com/lex and save in your first month.
那就是 betterhelp.com/lex。
That's betterhelp.com/lex.
本集节目还由 NetSuite 赞助，这是一套全方位的云端企业管理解决方案。
This episode is also brought to you by NetSuite, an all in one cloud business management system.
我研究战争越多，自然也就越研究商业，但战争让我愈发意识到组织架构、供应链和后勤的重要性——那些没人谈论、大多数历史学家也忽略的方面。
The more I study war, of course, the more I study business too, but war, the more I realize the importance of the organizational layer, of the supply chain, of the logistics, the stuff that nobody talks about, the stuff that most historians don't talk about.
实际上，我最近读了很多詹姆斯·霍兰德的作品，也与他交谈过，非常荣幸能与他交流，也很开心能向他学习。他是少数几位关注后勤、关注事物运作细节的历史学家之一。
And actually, I've read a lot of James Holland recently and spoken with him, had the great honor of speaking with him, had the great joy of speaking with him and learning from him, and he's one of the historians that does look at the logistics, does look at the details of how everything is run.
而NetSuite在企业环境中所做的，正是这些关于事物如何运作的细节。
And NetSuite in a company setting is doing exactly that, the details of how everything is run.
因为企业不仅仅是一个CEO带着一堆酷炫的想法，或者深夜的工程师蜷缩在桌前试图修复一个bug、寻找突破性创意。
Because a business is not just a CEO with a bunch of sexy ideas, or the late night engineer crouching over a table trying to fix a bug, trying to find a breakthrough idea.
不是的。
Nope.
它还包括所有其他真正让企业运转起来、提高效率、拥有优秀工具的方面。
It's also all the other stuff that actually make the thing work, make the thing efficient, have great tools to do so.
请前往netsuite.com/lex下载CFO的AI与机器学习指南。
Download the CFO's guide to AI and machine learning at netsuite.com/lex.
网址是netsuite.com/lex。
That's netsuite.com/lex.
本集节目还由Shopify赞助，这是一个为任何人打造精美在线商店、实现全渠道销售的平台。
This episode is also brought to you by Shopify, a platform designed for anyone to sell anywhere with a great looking online store.
既然我提到了历史，那么在古希腊，商旅网络至关重要；在罗马帝国，它们也同样重要；当然，成吉思汗时期更是极为重要。
Since I mentioned history, the merchant networks were crucially important in ancient Greece, were crucially important in the Roman Empire, and of course, Genghis Khan, very, very, very important.
当然，成吉思汗以保护商人而闻名。
Of course, Jenkis Khan is well known for protecting the merchants.
我认为，任何保护商人免受地缘政治摩擦、军事紧张和武装冲突影响的帝国或文明，都是成功的帝国与文明。
And I think any empires, any civilizations, any state of the global affairs that protects the merchants from the friction of geopolitics, of military tensions, and military conflicts is a successful empire, successful civilization.
因为贸易真的、真的非常重要。
Because trade is really, really important.
这是一种金融自由。
It's a kind of a financial freedom.
因此，在数字时代，我们构建像Shopify这样的系统，让你能够通过购物、销售和在数字世界中大规模建立市场来行使这种金融自由，这非常好。
So it's nice when in a digital age, we build systems like Shopify that allows you to exercise that financial freedom by buying stuff, selling stuff, create the market at scale in the digital world.
请前往shopify.com/luxe注册，享受每月1美元的试用期。
Sign up for a $1 per month trial period at shopify.com/luxe.
全部都是小写字母。
That's all lowercase.
立即前往 shopify.com/luxe，将您的业务提升到新高度。
Go to shopify.com/luxe to take your business to the next level today.
本集还由 AG one 赞助，这是一款全方位的日常饮品，有助于促进健康和提升表现。
This episode is also brought to you by AG one, an all in one daily drink to support better health and peak performance.
因为我提到了巅峰表现，我想起了尼采。
Because I mentioned peak performance, I'm reminded of Nietzsche.
在我大学一年级或二年级时读过的一本书，《查拉图斯特拉如是说》。
In the book I read maybe freshman, maybe sophomore year in college, thus spoke Zarathustra.
已经过去很久了。
It's been forever.
自从大学以来，我更多地阅读的是关于尼采的摘要，而不是直接阅读尼采的原著。
I've been reading summaries of Nietzsche, way more than Nietzsche directly since college.
我对人工智能的一个担忧就是，摘要、对摘要的再讨论效率太高、太有趣、太容易，甚至很有洞察力，以至于你不想再去读原始资料，因为那太费劲了。
That's one of the worries I have with AI is the summaries, the talking about the talking about the talking is so damn efficient and fun and easy and even insightful that you don't wanna go to the original sources because it's a lot of work.
但如果你想真正理解，就必须去读原著。
But you must, of course, if you wanna understand.
正如网络迷因所说，但你真的去过吗？
As the meme goes, but have you been there?
这永远不腻。
That never gets old.
无论如何，我在想一些经典作品，甚至十九、二十世纪的作品时，你确实想直接阅读马克思。
And anyway, I think about that with some of the classics, but even some of the twentieth century, nineteenth century works, you know, you wanna read Marx directly.
你确实想直接阅读尼采。
You wanna read Nietzsche directly.
你确实想直接阅读西格蒙德·弗洛伊德和卡尔·荣格。
You wanna read Sigmund Freud and Carl Jung directly.
当然，关于他们、他们的思想、总结他们的思想、扩展他们的思想、将他们置于适当背景下的好书很多，但没有什么能比直接阅读原作更棒。
Because, of course, there is great books about them, about their ideas, summarizing their ideas, elaborating on their ideas, putting them in the proper context, but there's nothing quite like reading it directly.
但无论如何，我提起这个是因为在《查拉图斯特拉如是说》中，追求人类巅峰潜能，而我们在西方，在健康方面，有时将这一点推向了近乎荒谬的地步。
But anyway, I brought I brought that up because in the thus, Bogsar at Thustria, there's the pursuit of peak human potential, And we in the West, on the health front, have at times taken that to an almost ridiculous place.
我觉得这仍然很有用，但有时放松一下、不那么较真，也挺好的。
I think it's still really useful, but sometimes it's also useful to fuck off a bit, to relax a bit, and not care.
有趣的是，AG 在某种方式上帮助我放松并不在意。
Funny enough, AG helps me in a certain kind of way, relax and not care.
我的营养已经安排好了。
I got my nutrition handled.
因为我每天喝 AG One，所以我能做各种疯狂的体力和脑力活动。
I can do all kinds of crazy physical stuff, mental stuff, because I'm drinking AG one.
当你在 drinkag1.com/lex 注册时，他们会送你一个月的鱼油。
They'll give you a one month supply of fish oil when you sign up at drinkag1.com/lex.
这是 Lex Freedom 播客。
This is the Lex Freedom Podcast.
为了支持我们，请查看描述中的赞助商。
To support it, please check out our sponsors in the description.
现在，亲爱的朋友，有请 Jenna Levin。
And now, dear friends, here's Jenna Levin.
你应该提到你给我发消息说不要早上太早开始，这让我觉得我们是志同道合的人。
I should say that you sent me a message about not starting early in the morning, and that made me feel like we're kindred spirits.
嗯。
Yeah.
你给我发消息说不早起，这让我觉得我们是志同道合的人。当时那位伟大的物理学家悉尼·科尔曼被要求参加早上9点的会议，他的回复是：‘我熬不到那么晚。’
You wrote to me when the great physicist Sydney Coleman was asked to attend a 9AM meeting, his reply was, I can't stay up that late.
嗯。
Yeah.
经典。
Classic.
悉尼深受爱戴。
Sydney was beloved.
我认为，所有最好的想法，老实说，嗯。
I think all the best thoughts, honestly Mhmm.
也许最糟糕的想法也都是在夜里产生的。
Maybe the worst thoughts too are all come at night.
夜晚有种特别的东西，也许是那份宁静。
There's something there's something about the night, maybe it's the silence.
嗯。
Mhmm.
也许是因为周围一片宁静。
Maybe it's the peace all around.
也许是因为黑暗，你可以独自一人，深入思考。
Maybe it's the darkness, and you just you could be with yourself and you could think deeply.
我觉得深夜里藏着一些被偷来的时间，因为那时没人打扰，设备也不会提示，根本没有任何压力要做事，但我经常在半夜醒来。
I feel like there's stolen hours in the middle of the night because it's not busy, your gadgets aren't pinging, there's really no pressure to do anything, but I'm often awake in the middle of the night.
所以这些就像是额外的白天时光。
And so it's sort of like these extra hours of the day.
我想我们凌晨四点还在互发消息。
I think we were exchanging messages at four in the morning.
好的。
Okay.
在这一点上，还有许多其他方面，我们都是志同道合的人。
So in that way, many other ways were kindred spirits.
那我们开始吧。
So let's go.
在宇宙中最酷的天体——黑洞中，它们到底是什么？
In one of the coolest objects in the universe, black holes, what are they?
也许一个好的起点是谈谈它们是如何形成的。
And maybe even a good way to start is to talk about how are they formed.
嗯。
Yeah.
某种程度上，人们常常混淆黑洞的形成方式与黑洞本身的概念。
In a way, people often confuse how they're formed with the concept of the black hole in the first place.
当黑洞首次被提出时，爱因斯坦对如此迅速地找到这样的解感到非常惊讶，但他真的认为自然会保护我们，避免它们的形成。
So when black holes were first proposed, Einstein was very surprised that such a solution could be found so quickly, but really thought nature would protect us from their formation.
然后，自然想出了一个方法来制造这些疯狂的天体，那就是让几颗恒星死亡。
And then nature thinks of a way nature thinks of a way to make these crazy objects, which is to kill off a few stars.
但我认为，人们容易混淆的是，那些死去的、质量极大的恒星与黑洞现象是等同的。
But then I think that there's a confusion that dead stars, these very, very massive stars that die, are synonymous with the phenomenon of black hole.
但这其实并不正确。
And it's really not the case.
黑洞比仅仅是恒星的死亡状态更为普遍和根本。
Black holes are more general and more fundamental than just the death state of a star.
但人们认识到恒星如何形成黑洞的历史也非常引人入胜，因为整个想法最初只是源于一个思想实验。
But even the history of how people realize that stars could form black holes is is is quite fascinating, because the entire idea really just started as a thought experiment.
如果你想想，1915年到1916年，爱因斯坦以一种被广泛接受的形式完整地描述了相对论。
And if you think of it's 1915, 1916 when Einstein fully describes relativity in a way that's the canonical formulation.
在此之前，理论经历了许多反复的修改。
It was a lot of changing back and forth before then.
当时正值第一次世界大战，他收到东线一位朋友的来信，这位朋友是卡尔·史瓦西，他解出了爱因斯坦的方程——就是在战壕里、炮火纷飞的间隙完成的。
And it's World War one, and he gets a message from the Eastern Front from a friend of his, Carl Schwarzschild, who's who's solved Einstein's equations, you know, between sitting in the trenches and, like, cannon fire.
人们开玩笑说，他当时在计算弹道轨迹。
It was joked that he was calculating ballistic trajectories.
同时，他也在阅读普鲁士科学院的会议记录，就像你平时做的那样。
He's also perusing the proceedings of the Prussian Academy of Sciences, as you do.
我想。
I think.
他是一位天文学家，四十多岁时参军，却找到了爱因斯坦方程的一个非常非凡的解。
And he was an astronomer, who had enlisted in his forties, and he finds this really remarkable solution to Einstein's equations.
这是第一个精确解。
And it's the first exact solution.
他并没有称它为黑洞。
He doesn't call it a black hole.
几十年后，它才被称为黑洞。
It's not called a black hole for decades.
但我喜欢施瓦西所做的，这是一场思想实验。
But what I love about what Schwarzschild did is it's a thought experiment.
这与观测无关。
It's not about observations.
也不是关于在自然界中制造这些东西。
It's not about making these things in nature.
这真的只是关于这个想法。
It's really just about the idea.
他设定了一个完全不可行的情境。
He sets up this completely untenable situation.
他说，想象我把一颗恒星的所有质量压缩成一个点。
He says, imagine I crush all the mass of a star to a point.
别问这是怎么做到的，因为这真的荒谬至极。
Don't ask how that's done because that's really absurd.
但我们就假设一下，想象这是一个可能的情景。
But let's just pretend, and let's just imagine that that that's a scenario.
然后他想弄清楚，如果我设定这个令人困惑却异常简单的场景，时空会发生什么变化。
And then he wants to decide what happens to space time if I set up this confounding but somehow very simple scenario.
实际上，当时爱因斯坦方程告诉所有人的是：物质和能量会弯曲时空，而弯曲的时空则决定物质和能量如何在已弯曲的时空中运动。
And, really, what Einstein's equations were were telling everybody at the time was that matter and energy curve space and time, and then curved spacetime tells matter and energy how to fall once the spacetime's shaped.
因此，他找到了一个优美的解，而这个解最令人惊叹的地方在于，他发现了所谓的事件视界——一个连光都无法逃脱的区域。
So he finds this beautiful solution, and the most amazing thing about his solution is he finds this demarcation, which is the event horizon, which is the region beyond which not even light can escape.
如果今天你问我，距离那个想法已经过去了一个多世纪，我会说那就是黑洞。
And if you were to ask me today all these decade over a hundred years later, I would say that is the black hole.
黑洞并不是被压缩成一点的质量。
The black hole is not the mass crushed to a point.
黑洞是事件视界。
The black hole is the event horizon.
事件视界实际上只是时空中的一个点或一个区域。
The event horizon is really just a point in space time or or a region at space time.
在这种情况下，它实际上是时空中的一个表面，标志着事件的分界，因此被称为事件视界。
It's actually, in this case, a surface in space time, and it marks a a separation in events, which is why it's called an event horizon.
事件视界之外的一切在因果上与内部隔绝，因为事件视界内部的事物无法影响外部的事件。
Everything outside is causally separated from the inside insofar as what's inside the event horizon can't affect events outside.
外部的事物可以影响内部的事件。
What's outside can affect events inside.
我可以将一个探测器扔进黑洞，从而在内部引发某些事件，但反之则不成立。
I can throw a probe into a black hole and cause something to happen on the inside, but the opposite isn't true.
掉进去的人无法向外发送探测器。
Somebody who fell in can't send a probe out.
这种单向性正是黑洞最深刻的地方。
And this one way aspect really is what's profound about the black hole.
有时我们说黑洞什么都没有，因为在事件视界处实际上什么都没有。
Sometimes we talk about the black holes being nothing because at the event horizon, there's really nothing there.
当我们想象黑洞时，有时会想到一个极其致密的死星。
Sometimes when we when we think about black holes, we wanna imagine a really dense dead star.
但如果你靠近事件视界，它只是一个空旷的时空区域。
But if you go up to the event horizon, it's an empty region of space time.
它更像一个地方，而不是一个物体。
It's it's more of a place than it is a thing.
爱因斯坦对此感到着迷。
And Einstein found this fascinating.
他帮助推动了这项研究的发表，但他真的不认为黑洞会在自然界中形成。
He helped get the work published, but he really didn't think these would form in nature.
我怀疑卡尔·施瓦西也没有。
I doubt Carl Schwarzschild did either.
我认为他们当时以为自己只是在解决理论数学问题，而不是在描述后来被证实的引力坍缩的最终状态。
I think they thought they were, solving theoretical mathematical problems, but not describing this what turned out to be the end state of gravitational collapse.
也许思想实验的目的是找出理论的局限性。
And maybe the purpose of the thought experiment was to find the limitations of the theory.
所以你要找到最极端的版本，以便理解它在何处失效。
So you you find the most extreme versions in order to understand where it breaks down.
是的。
Yeah.
而碰巧的是，在这种情况下，它可能确实预测了这些极端天体的存在。
And it just so happens in this case that might actually predict these extreme kinds of objects.
它两者都做到了。
It does both.
所以它也能描述远处的太阳。
So it also describes the sun from far away.
因此，同一个解在帮助我们理解地球绕太阳的轨道方面表现得非常出色。
So the same solution does a great job helping us understand the Earth's orbit around the sun.
不可思议。
Incredible.
它表现得非常好。
It does a great job.
这几乎是大材小用了。
It's almost overkill.
你其实并不需要像相对论那样精确。
You don't really need to be that precise as relativity.
而且，是的，它预测了黑洞现象，但并没有真正解释自然界是如何形成它们的。
And, yes, it predicts the phenomenon of black holes, but doesn't really explain how nature would form them.
但除此之外，它还暗示了理论的失效。
But then it also, on top of that, does signal the breakdown of the theory.
我的意思是，你在这方面说得对。
I mean, you're quite right about that.
它实际上说：天哪。
It actually says, oh, man.
但当你一直深入到中心时，嗯，这听起来就不对了。
But you you go all the way towards the center, and, yeah, this doesn't sound right anymore.
有时候我会把它比作一个垂死的人在地上划写，表示这里出了问题。
Sometimes I liken it to you know, it's like a dying man marking in the dirt that something's gone wrong here.
对吧？
Right?
它在暗示，一定有什么地方出了问题。
It it it's signaling that that there's some culprit.
这个理论中存在某种错误。
There's something wrong in the theory.
就连罗杰·彭罗斯，这位致力于理解引力坍缩形成黑洞的学者，也曾认为：哦，是的。
And and even Roger Penrose, who did this general work trying to understand the formation of black holes from gravitational collapse, he thought, oh, yeah.
奇点是不可避免的。
There's a singularity that's inevitable.
一旦形成了黑洞，这就无处不在，无法避免。
It's in every there's no way around it once you form a black hole.
但他表示，这很可能只是因为我们忽略了量子力学所致的局限，一旦我们将量子力学纳入考虑，就会以不同的方式理解这一点。
But he said this is probably just a shortcoming of the fact that we've forgotten to include quantum mechanics, and that when we do, we'll understand this, differently.
所以根据他的观点，你越接近奇点，量子力学的作用就越显著，因此并不存在奇点。
So according to him, the closer you get to the singularity, the more quantum mechanics comes into play, and therefore, there's no singularity.
而是存在其他东西。
There's something else.
我想每个人都会这么说。
I think everybody would say that.
我想每个人都会认为，当你越接近奇点时，毫无疑问，必须引入量子力学。
I think everybody would say the closer you get to the singularity, for sure, you have to include quantum mechanics.
你不可能在讨论如此微小的尺度、如此巨大的撕裂、弯曲和能量尺度时，却不包含量子力学，这根本说不通。
You just can't consistently talk about magnifying such small scales, having such enormous ruptures and and curvatures and energy scales and not include quantum mechanics.
这与我们对世界的理解完全不一致。
That that's just inconsistent with the world as we understand it.
所以你描述了一个令人震撼的观点：黑洞与其说像通常所说的超密集物质，不如说更像一个时空区域，甚至更准确地说，就是虚无。
So you've described the brain breaking idea that a black hole is not so much a super dense matter as it's sometimes described, but it's more akin to, you know, a region of space time, but even more so just nothing.
是的。
Yeah.
就是虚无。
It's nothing.
这似乎是你喜欢说的那句话？
That that's the thing you seem to like to say?
没错。
I do.
我喜欢说黑洞是‘无物’。
I do like to say that black holes are no thing.
无物。
No thing.
虚无。
Nothing.
好的。
Okay.
那这意味着什么？
So what what what does that mean?
这就是我的意思。
That's what I mean.
这才是黑洞更深刻的一面。
That's the more profound aspect of the black hole.
你最初问的是，它们是如何形成的？
So you asked originally, how do they form?
我认为，即使在复杂的天体物理系统中试图形成黑洞，最终留下的仍然什么都没有。
And I think that that that even when you try to form them in messy astrophysical systems, there's still nothing at the end of the day left behind.
尽管爱因斯坦接受了这是正确的预言，但这仍然令人非常惊讶。
And, this was a very big surprise even though Einstein accepted that this was a true prediction.
他并不认为黑洞真的会形成，而像奥本海默这样的人实际上——这可能是奥本海默最重要的理论工作——他们研究核物理和量子力学，却是在这些乌托邦式问题的背景下进行的。
He didn't think that that they'd be made, and and it was quite astounding that that people like Oppenheimer actually, it's probably Oppenheimer's most important theoretical work, who were thinking about nuclear physics and quantum mechanics, but in the context of these kind of utopian questions.
为什么恒星会发光？
Why do stars shine?
为什么太阳如此明亮、炽热，成为如此奇妙的光源？
Why is the sun radiant and hot and this amazing source of light?
正是像奥本海默这样的人开始提出问题：恒星是否可能坍缩形成黑洞？
And it was people like Oppenheimer who began to ask the question, well, could stars collapse to form black holes?
它们是否可能变得如此致密，以至于连光都无法逃脱？
Could they become so dense that, eventually, not even light would escape?
这就是为什么人们认为黑洞是这些致密天体的原因。
And that's why I think people think that black holes are these dense objects.
这通常是人们对其的描述。
That's often how it's described.
但实际上，这些质量极大的恒星正在燃烧热核燃料。
But, actually, what happens, these very massive stars, they're burning thermonuclear fuel.
你知道，它们内部充满了热核燃料，正在燃烧并以E=mc²的形式释放能量。
You know, they're earth fulls of thermonuclear fuel they're burning, and emitting energy in e equals m c squared energy.
所以它在进行聚变。
So it's fusing.
它就像一颗聚变炸弹。
It's a fusion bomb.
它是一颗持续爆炸的热核炸弹。
It's a constantly going thermonuclear bomb.
最终，它会耗尽燃料。
And, eventually, it's gonna run out of fuel.
它会耗尽氢和氦等可聚变的物质。
It's gonna run out of hydrogen, helium stuff to fuse.
它会形成一个铁芯。
It hits an iron core.
要通过聚变超越铁元素实际上需要消耗大量能量，因此它不再那么容易继续进行。
Iron to go past iron with fusion is actually energetically expensive, So it's no longer going to do that so easily.
所以突然间，它耗尽了燃料。
So suddenly, it's run out of fuel.
如果一颗恒星非常、非常、非常巨大，比我们的太阳重得多，可能是太阳质量的二十到三十倍，它就会在自身重力下坍缩。
And if the star is very, very, very massive, much more massive than our sun, maybe twenty, thirty times the mass of our sun, it'll collapse under its own weight.
这种坍缩极其迅速且剧烈，并产生冲击波。
And that collapses incredibly fast and dramatic, and it creates a shock wave.
这就是超新星爆炸。
So that's the supernova explosion.
因此，很多情况下，当它们被压缩后，会达到一个新的临界点，能够重新点燃并形成更重的元素，这本质上就像引爆了一颗炸弹。
So a lot of these, they rebound because once they crunch, they've reached a new critical capacity where they can reignite to higher elements, heavier elements, and that sets off a bomb, essentially.
于是恒星爆炸了，而这恰恰对我们有利，因为这就是你我存在的原因。
So the star explodes, helpfully, because that's why you and I are here.
因为恒星会将物质抛回太空，而你我正是由碳、氧以及这些宝贵元素构成的。
Because stars send their material back out into space, and you and I get to be made of carbon and oxygen and all this good stuff.
我们不仅仅是氢元素。
We're not just hydrogen.
所以恒星为我们做了这一切。
So the suns do that for us.
而剩下的部分有时会形成中子星，这是一种非常酷、非常奇妙的天体，密度极高，但比黑洞大，也就是说，它还不够致密，无法形成黑洞。
And then what's left sometimes ends at a neutron star, which is a very cool object, very fascinating object, super dense, but bigger than a black hole, meaning it's it's it's not compact enough to become a black hole.
它是一个真实存在的东西。
It's an actual thing.
中子星是真实存在的。
A neutron star is a real thing.
它就像一个巨大的中子。
It's like a giant neutron.
literally，电子被挤压进质子中，形成一个巨大的原子核和一种超导物质。
Literally, electrons get jammed into the protons and make this giant nucleus and this superconducting matter.
非常奇特。
Very strange.
奇妙的天体。
Amazing objects.
但如果核心更重，也就是超过太阳质量的两倍，它就会变成黑洞。
But if it's heavier than that, the core, and that's, you know, heavier than twice the mass of the sun, it will become a black hole.
奥本海默在1939年与他的学生合著了一篇优美的论文，认为引力坍缩的最终状态实际上就是黑洞。
And Oppenheimer was wrote this beautiful paper in 1939 with his student, saying that they believed that the end state of gravitational collapse is actually a black hole.
这令人震惊，真是一种富有远见的结论。
This is stunning and really, a visionary conclusion.
这篇论文发表的同一天，纳粹进军波兰，因此在报纸上并未引起太多关注。
Now the paper's published the same day the Nazis advance on Poland, and so it does not get a lot of fanfare in the newspaper.
是吗？
Is it?
我们认为，如今社交媒体上每天都有很多戏剧性事件。
We think there's a lot of drama today on social media.
跟这个比一比。
Match that.
是的。
Yes.
想象一下，有个人预测了自然界中这种最激进的天体的形成方式，甚至连爱因斯坦都难以接受。
Like, here's a guy who predicts how actually in nature would be the formation of this most radical of object that broke even Einstein's brain Mhmm.
与此同时，历史上最邪恶的人之一，甚至可能是最邪恶的人，拉开了全球战争的序幕。
While one of the most evil, if not the most evil humans in history, starting, the first steps of a global war.
我也喜欢这个故事所体现的科学的中立性。
What I also love about that lesson is how agnostic science is.
是的。
Yeah.
因为他当时和其他人一样，提出了关于核物理和恒星的乌托邦式问题。
Because he was asking these utopian questions as were other people at the time about the nuclear physics and stars.
你可能知道迈克尔·弗雷恩的戏剧《哥本哈根》。
You might know this play Copenhagen by Michael Frain.
剧中有一句他归于玻尔的话，玻尔是早期量子力学奠基人、丹麦物理学家，他说服妻子：还没人想到用量子力学来杀人。
There's this line that he attributes to Bohr, and Bohr was the great thinker of early foundations of quantum mechanics, Danish physicist, where Bohr says to his wife, nobody's thought of a way to kill people using quantum mechanics.
当然，后来就出现了原子弹。
Now, of course, then there's the nuclear bomb.
我欣赏的是，当时科学家们承受着巨大压力，必须将核物理应用于实战，加入这场核武器竞赛。
And what I love about this was the pressure scientists were under to do something with this nuclear physics and and to enter this race over, a nuclear weapon.
但事实上，1939年，奥本海默当时正在思考黑洞。
But, really, at the same time, 1939, really, Oppenheimer's thinking about black holes.
克里斯托弗·诺兰的电影里甚至有一句很小的台词。
There's a there's even a small line in Chris Nolan's film.
很难注意到。
It's very hard to catch.
电影中有一个地方，他们是在开玩笑时提到这一点的。
There's a reference to it in the film where he they're sort of joking.
好吧，我想现在没人会关注你的论文了，你知道的，因为纳粹正在进攻波兰。
Well, I guess nobody's gonna pay attention to your paper now, you know, because because of the Nazi advance on Poland.
奥本海默的另一个了不起之处在于，他也是原子弹研制的核心人物。
That's the other remarkable thing about Oppenheimer is he's also a central figure in the construction of the bomb.
没错。
Right.
所以这是理论与实验的碰撞，对吧。
So it's theory and experiment clashing together Right.
涉及地缘政治。
With the geopolitics.
没错。
Exactly.
因此，作为原子弹之父的奥本海默，谈到了‘毁灭世界的人’。
So, of course, Oppenheimer, now known as the father of the atomic bomb, he talks about destroyers of worlds.
但这是同一种技术，这就是我所说的科学是中立的。
But it's the same technology, and that's what I mean by science is agnostic.
对吧？
Right?
同一种技术，克服临界质量，引发热核聚变。
It's the same technology, overcoming a critical mass, igniting thermonuclear fusion.
最终，发生了裂变。
Eventually, there was a fission.
最初的原子弹是裂变炸弹，而裂变最早由莉泽·迈特纳揭示：她发现当用质子轰击某种铀时，它会分裂成比铀更小的碎片。
The original bomb was a fission bomb, and fission was first shown by Lise Meitner who showed that a certain uranium, when you bombarded it with protons, broke into smaller pieces that were less than the uranium.
对吧？
Right?
所以，那部分质量，即爱因斯坦的质能方程 E=mc² 中的能量，已经释放出来了。
So some of that mass, that e equals m c squared energy, had escaped.
这是爱因斯坦最著名方程的首次具体实证。
And it was the first kind of concrete demonstration of this Einstein's most famous equation.
所以这一切都汇聚在一起了。
So all of this comes together.
但当时，它们还不叫黑洞。
But the story of, they still weren't called black holes.
这是1939年。
This is 1939.
人们用非常冗长的方式描述引力坍缩的最终状态——灾难性的终结状态。
And they had these very long winded ways of describing the end state, the catastrophic end state of gravitational collapse.
但你必须想象的是，当这颗恒星坍缩时，那么太阳呢？
But what you have to imagine is as this star collapses so now so what's the sun?
太阳的直径有一百五十万公里。
The sun's a million and a half kilometers across.
想象一颗比太阳大得多、半径大得多的恒星，它如此沉重。
So imagine a star much bigger than the sun, much bigger radius, and it's so heavy.
它开始坍缩。
It collapses.
它发生了超新星爆发。
It's supernovas.
剩下的核心质量可能仍有太阳的十倍左右，并继续坍缩。
What's left is still maybe 10 times the mass of the sun, just what's left in that core, and it continues to collapse.
当它坍缩到大约六十公里宽时，想象一下，十倍于太阳质量的物质，压缩成一座城市大小，这是一个极其致密的天体。
And when that reaches about 60 kilometers across, like, just imagine 10 times the mass of the sun, city sized, That is a really dense object.
此时，黑洞实际上已经开始形成，意味着时空的弯曲如此剧烈，连光都无法逃脱。
And now the black hole essentially has begun to form, meaning the curve in spacetime is so tremendous that not even light can escape.
事件视界形成了，但事件视界几乎被烙印在时空之中，因为恒星无法再维持这种致密状态，就像它无法以光速向外飞驰一样——甚至连光都被迫向内坠落。
The event horizon forms, but the event horizon is almost imprinted on the space time because the star can't sit there in that dense state any more than it can race outward at the speed of light because even light is forced to rain inwards.
所以恒星继续坍缩，这就是神奇的部分。
So the star continues to fall, and that's the magic part.
恒星将事件视界抛在身后，继续下坠。
The star leaves the event horizon behind, and it continues to fall.
它坠入了黑洞的内部。
And it falls into the interior of the black hole.
它去了哪里，没人真正知道，但它已从视野中消失。
Where it goes, nobody really knows, but it's gone from sight.
它变得黑暗。
It goes dark.
这里有一句约翰·惠勒的名言，他是美国相对论的泰斗，他说过类似这样的话。
There's this quote by John Wheeler who's like granddaddy of American relativity, and he has a line that's something to the effect.
恒星就像柴郡猫一样渐渐消失。
The star like the Cheshire cat fades from view.
只留下它的微笑。
One leaves behind only its grin.
另一个，只剩下它的引力吸引。
The other, only its gravitational attraction.
他当时正在做一场讲座。
And he was giving a lecture.
实际上，那个地方就在汤姆餐厅上方，你知道的，就是《宋飞正传》里那个靠近哥伦比亚大学的纽约餐厅。
It's actually above Tom's restaurant, you know, from Seinfeld near Columbia in New York.
不错。
Nice.
那里曾经有个地方，或者现在仍然有个地方，人们在那里举办关于天体物理学的讲座，那是1967年。
There was a a a place or there still is a place there where people were giving lectures about astrophysics, and it's 1967.
惠勒正在详尽地使用这个充满分量的术语：灾难性引力坍缩的最终状态。
Wheeler is exhaustively saying this loaded term, the end state of catastrophic gravitational collapse.
传闻说，有人从后排喊道：那叫黑洞怎么样？
And rumor is that someone shouts from the back row, well, how about black hole?
而据称，他随后便将这个术语推广到了全世界。
And, apparently, he then foists this term on the world.
惠勒就是这样做事的。
Wheeler had a way of doing that.
嗯，我喜欢这样的术语。
Well, I love terms like that.
大爆炸，黑洞。
Big bang, black hole.
嗯。
Mhmm.
有些术语其实就是直接指出房间里的大象，并叫它大象。
There's some I mean, it's just pointing out the elephant in the room and calling it an elephant.
那就是一个黑洞。
It is a black hole.
嗯。
Mhmm.
这是一个非常准确且深刻的描述。
That's a pretty accurate and deep description.
我只是想指出，这是奥本海默1939年的一篇论文，第一次看的时候。
I just wanted to point out that the just looking for the first time, it's a 1939 paper from Oppenheimer.
它只有两页，差不多三页。
It's like two page it's like three pages.
哦，是的。
Oh, yeah.
太美了。
It's gorgeous.
这些理论的简洁性，真是酷到爆。
Simplicity of some of these, that's so gangster.
仅凭这些就彻底改变了整个物理学，爱因斯坦曾多次做到这一点。
Just revolutionize all of physics with this with, know, Einstein did that multiple times in
在差不多同一年。
a similar year.
嗯。
Mhmm.
当所有热核能源耗尽时，足够重的恒星将会坍缩。
When all thermonuclear sources of energy are exhausted, a sufficiently heavy star will collapse.
这真是个开场白。
That's an opener.
嗯。
Mhmm.
除非由于自转、辐射质量损失或辐射导致的质量抛射使恒星质量降至太阳质量的若干数量级以下，否则这种坍缩将无限持续下去。
Unless fission due to rotation, the radiation of mass, or the blowing off of mass by radiation reduce the star's mass to orders of that of the sun, this contraction will continue indefinitely.
嗯。
Mhmm.
就这样一直持续下去。
And it goes on that way.
是的。
Yeah.
现在我得说，真正提出‘黑洞’这个术语的惠勒，对奥本海默的这个观点提出了严厉的批评。
Now I have to say that Wheeler, who actually coins the term black hole, gives Oppenheimer quite a terrible time about this.
他认为他错了。
He thinks he's wrong.
他们之间出现了某种被称为激烈争执的关系，我不确定是否算得上是敌对，但确实存在不和。
And they entered what has sometimes been described as kind of a bitter I don't know if you would actually say feud, but there were bad feelings.
惠勒实际上花了数十年时间，坚持认为奥本海默是错的。
And, Wheeler actually spent decades, saying Oppenheimer was wrong.
而最终，通过他的计算机工作——惠勒在研究核武器时也进行过早期的计算机工作。
And eventually, with his computer work, that early work that Wheeler was doing with computers when he was also trying to understand nuclear weapons.
在和平时期，世界再次回归到这些天体物理问题，并最终认定奥本海默其实是对的。
And in peacetime, world found themselves returning again to these astrophysical questions, decided that actually Oppenheimer had been right.
他认为他们所采用的设定过于简化和理想化，如果考虑更现实、更复杂的情况，这种现象根本就不会出现。
He thought it was too simplistic to idealized a setup that they had used, and that if you you looked at something that was more realistic and more complicated, that it it just simply it just would go away.
事实上，他得出了完全相反的结论。
And in fact, he he draws the opposite conclusion.
有一个故事说，当惠勒宣布黑洞极有可能是超大质量恒星引力坍缩的最终状态时，奥本海默正坐在礼堂外。
And there's a story that Oppenheimer was sitting outside of the auditorium when Wheeler was coming forth with his declaration that, in fact, black holes were the likely end state of gravitational collapse for very, very heavy stars.
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当被问及此事时，奥本海默只是说，我已经转向其他事情了。
And, when asked about it, Oppenheimer sort of said, well, I've moved on to other things.
因为你曾在许多地方写过科学背后的人类。
Because you've written in many places about the human beings behind the science.
嗯。
Mhmm.
我必须问你关于核武器的事，这些最伟大的物理学家们聚集在一起，创造了这种最恐怖、最强大的技术。
I have to ask you about this, about nuclear weapons, where is the greatest of physicists coming together to create this most terrifying and powerful of a technology.
而现在，我有机会与世界领导人交谈，对他们来说，这项技术是地缘政治棋盘上可能被隐性使用的一种工具。
And now I get to talk to world leaders for whom this technology is part of the tools that is used perhaps implicitly on the chessboard of geopolitics.
作为一名物理学家，研究过物理学家并写过这些科学背后的人类，对于这个物理学家们齐聚一堂、创造出足以毁灭整个人类文明的武器的历史时刻，你有什么看法？
What what can you say, as a person who's a physicist and who have studied the physicists and written about the physicists, the humans behind this, about this moment in human history when physicists came together and created this weapon that's powerful enough to destroy all of human civilization.
我认为这是科学史上一个极其痛苦的时刻。
I think it's an excruciating moment in in the history of science.
人们常谈到海森堡，他留在德国，为纳粹工作，试图研制原子弹。
And people talk about Heisenberg who stayed in Germany and and, worked for the Nazis in their own attempt to build the bomb.
当时有一种充满希望的说法，认为海森堡可能故意阻挠了核武器计划，但我认为这种观点基本已被驳斥——如果他愿意，他是能制造出原子弹的。
There was this kind of hopeful talk that maybe Heisenberg had intentionally derailed the nuclear weapons program, but I think that's been largely discredited that he would have made the bomb, could he?
如果他没有在最初估算所需材料数量或如何克服能量壁垒时犯下一些非常简单的错误的话。
Had he not made some really kind of simple errors in his original estimates about how much material would be required or how they would get over the energy barriers.
这是一个令人恐惧的想法。
And that's a terrifying thought.
我不知道我们中的任何人是否真的能设身处地地想象，面对这样的困境：必须主动参与思考如何将量子力学用于杀人，并最终制造出原子弹。
I I don't know that any of us can really put ourselves in that position of imagining that we're faced with that quandary, having to take the initiative to participate in thinking of a way that quantum mechanics can kill people and then making the bomb.
我认为，如今绝大多数物理学家都认为，我们不应继续推进核武器的扩散。
I think overwhelmingly, physicists today feel we should not continue in the proliferation of nuclear weapons.
极少有理论物理学家希望这种状况继续下去。
Very few theoretical physicists wanna see this continue.
那个历史时刻，苏联拥有杰出的科学家，纳粹德国拥有杰出的科学家，美国也拥有杰出的科学家。
That moment in history, The Soviet Union had incredible scientists, Nazi Germany had incredible scientists, and The United States had incredible scientists.
很容易想象，这三个国家中的任何一个都可能率先制造出原子弹，而不是美国。
And it's very easy to imagine that one of those three would have created the bomb first, not The United States.
是的。
Yes.
那么世界会有什么不同？
And how different would the world be?
那种博弈论，嗯。
The game theory of that Mhmm.
我认为，如果美国有33%的概率率先研制出原子弹，那么如果苏联拥有原子弹，我认为他们会在欧洲战场以更可怕的方式使用它，甚至可能反过来对付美国。
I think, say, if the probability is 33% that it was The United States, if The Soviet Union had the bomb, I think I think they would have used it in a much more terrifying way in the in the European theater and maybe turn on The United States.
显然，希特勒也会使用它。
And, obviously, with Hitler, he would have used it.
毫无疑问，他会用它来杀死数亿人。
I think there's no question he would have used it to to to to kill hundreds of millions of people.
在博弈论的版本中，这是最不有害的结果。
In the game theory version, this was the least harmful outcome.
是的。
Yes.
是的。
Yes.
但没有原子弹的结果，嗯，
But there is no outcome with no bomb that Yeah.
任何博弈论学者都不会选择的那种结果。
That any game theorist would, I think would play.
但我想，如果我们抛开地缘政治、意识形态和邪恶的独裁者，这些人本质上都是科学家。
But I I think if we just remove the geopolitics and the ideology and the evil dictators, all of those people are just scientists.
我认为他们未必会考虑意识形态问题。
I think they don't necessarily even think about the ideology.
这深刻地揭示了伟大科学与那些利用科学实现好坏目的的、令人头疼甚至邪恶的政治家之间的联系。
And it it's a it's a it's a deep lesson about the connection between great science and the annoying, sometimes evil politicians that use that science for means that are either good or bad.
嗯。
Mhmm.
而科学家们，天啊，他们对科学的用途真的能掌控多少呢？
And the scientists perhaps don't boy, do they even have control of how that science is used as hard?
没有控制权。
Don't have control.
对。
Right.
一旦制造出来，决定其用途的就不再是科学推理，而是克制。
Once it's once it's made, it's no longer scientific reasoning that dictates the use or, it's restraint.
但我要说，我认为这并不是因为三十年后美国的情况不同了。
But I will say that I do believe that it wasn't a thirty one third down the line because America was different.
我认为在当前这种特定的氛围下，我们必须思考这一点。
And I think that's something we have to think about right now in this particular climate.
这么多科学家逃到了这里。
So many scientists fled here.
他们逃到了这里。
They fled to here.
美国人并没有逃往纳粹德国。
Americans weren't fleeing to Nazi Germany.
他们来到这里，受到的驱动力不仅仅是爱国主义。
They came here, and and they were motivated, by, it's more than a patriotism.
你知道吗？
You know?
我的意思是，这当然是爱国主义，但又不止于此。
It's I mean, it was a patriotism, obviously, but it was sort of more than that.
他们真正理解了欧洲的威胁，当时欧洲正在发生什么，以及那种自由奔放的柏林文化是如何迅速转变为一个压抑而恐怖的政权的。
It was really understanding the threat of Europe, what was going on in Europe, and and what that life's how quickly it turned, how quickly this free spirited Berlin culture, you know, was suddenly in this repressive and terrifying, regime.
所以我认为，这件事在美国发生的可能性要大得多。
So I think that it was a much higher chance that it happened here in America.
是的。
Yeah.
美国体制有一些独特之处。
There's something about the American system.
这虽然老生常谈，但自由——各种各样的个人自由，确实能催生一个充满活力的科学界，至少在最好的时候是这样。
The you know, it's cliche to say, but the freedom, all the different individual freedoms that enable a very vibrant, at its best, a very vibrant scientific community.
这真的令人兴奋
And that's really exciting
当然。
Absolutely.
对科学家来说，保持这一点对我来说非常重要。
To scientists, and it's very valuable to me maintain that.
没错。
Right.
这种充满活力的辩论、资金和这些机制。
The the vibrancy of the debate of the funding those mechanisms.
当然。
Absolutely.
全世界的人都涌向这里，如果我们不再拥有思想自由，这种情况就不会再发生了。
The world flocked here, and that won't be the case if we no longer have intellectual freedom.
是的。
Yeah.
有一个有趣的问题值得思考，那就是21世纪中国与美国之间的紧张关系和冷战态势。
There's there's something interesting to think about tension, the Cold War between China and The United States in the twenty first century.
你知道，一些同样的问题和观点会再次浮现，我们希望确保科学思想能够自由、活跃地交流。
You know, some of those same questions, some of those ideas will rise up again, and we wanna make sure that there's a vibrant, free exchange of scientific ideas.
我认为大多数诺贝尔奖得主都来自美国。
And I believe most Nobel Prizes come from The United States.
对吧？
Right?
哦，是的。
Oh, yeah.
我没有确切的数字，但是……
I don't have the number, but
是的。
I so.
比例远超其他国家。
Disproportionately so.
事实上，许多粒子物理学家来自布朗克斯，他们是欧洲移民。
In fact, a lot of them from particle physics came from the Bronx, and they were European immigrants.
你如何解释这一点？
How do you explain this?
他们正是因为我们所描述的地缘政治而逃离欧洲。
Fled Europe, precisely because of the geopolitics we're describing.
是的。
Yeah.
因此，他们不是来自苏联或东欧集团的诺贝尔奖得主，而是来自布朗克斯。
And so instead of being Nobel Prize winners from the Soviet Union or from the Eastern Bloc, they were from The Bronx.
这就是你所写的，我们会一再回到这一点：科学是由人类完成的，而其中一些人非常有趣。
And that that's the thing you write about, and we'll return to time and time again that, you know, science is done by humans, and some of those humans are fascinating.
存在紧张关系。
There's tensions.
存在斗争。
There's battles.
有些人是独行者，有些人是出色的合作者，有些人备受折磨，有些人随和自在，诸如此类。
There's some are loners, some are great collaborators, some are tormented, some are easygoing, all this kind of stuff.
这正是它的美妙之处，我们有时会忘记，科学是由人类完成的，而人类是混乱、复杂而又美丽的。
And that's the beautiful thing about it, we forget sometimes is it's humans, and humans are messy and complicated and beautiful and all of that.
是的。
Yeah.
那我们刚才在谈什么？
So what were we talking about?
哦。
Oh.
恒星正在坍缩。
The star is collapsing.
好的。
Okay.
那我们能不能再回到恒星坍缩形成黑洞这个话题？
So can we just return to the collapse of a star that forms a black hole?
在哪个时刻，这个超密集的物体最终变成虚无？如果我们能稍微深入思考一下这个概念的话？
At which point does the super dense thing become nothing, if we can just, like, linger on this concept?
是的。
Yeah.
如果我正坠入一个黑洞，并且在我刚穿过这个空无区域、也就是这个分界线时，我拼命地试图行动，而我恰好知道它在哪里。
So if I were falling into a black hole and I I I tried really fast right as I crossed this empty region, but this demarcation, I happened to know where it was.
我计算过了，因为那里根本没有线。
I calculated because there's no line there.
那里没有任何迹象表明它存在。
There's no sign that it's there.
没有任何路标。
There's no signpost.
我可以发射一束微弱的光脉冲，正好在事件视界处向外发送。
I could emit a little light pulse and try to send it outward exactly at the event horizon.
所以它正以光速向外飞驰。
So it's racing outward at the speed of light.
它能悬停在那里，因为从我的角度来看，这非常奇怪。
It can hover there because from my perspective, it's very strange.
时空就像一场倾泻而下的瀑布，而我正被卷入其中，嗯。
The space time is like a waterfall raining in, and I'm being dragged in Mhmm.
随着那场瀑布。
With that waterfall.
我无法在事件视界处停住。
I can't stop at the event horizon.
它来了。
It comes.
它走了。
It goes.
它迅速地从我身后掠过。
It's behind me really quickly.
那束光试图停在那里，就像一条鱼逆着尼亚加拉瀑布游动，你知道的，停在瀑布前。
That light beam can try to sit there because it's like it's like a fish swimming against the Niagara, you know, sitting against a waterfall.
它就像卡在那里。
It's, like, stuck there.
但它就像卡在那里。
But it's, like, stuck there.
嗯。
Mhmm.
所以这是一种方式，你可以有一个小小的路标。
And so that's one way you can have a little signpost.
你知道，如果你飞过去，你会觉得它以光速移动。
You know, if you fly by, you think it's moving at the speed of light.
嗯。
Mhmm.
它以光速从你身边飞过，但它却静静地停在事件视界上。
It flies past you at the speed of light, but it's sitting right there at the event horizon.
所以你正在下落，穿过事件视界，在那一刻，你向外发射了一个光子。
So you're falling back, crossing the event horizon, right at that point, you shoot outwards a photon.
是的。
Yes.
它就卡在那里。
And it's just stuck there.
它就是卡在那里。
It just gets stuck there.
现在它非常不稳定。
Now it's very unstable.
重点是，恒星无法停在那里。
So the star can't sit there is the point.
它就是不行。
It it just can't.
所以它像瀑布一样向内坠落。
So it rains inward with this waterfall.
但从外部来看，我们真正应该关心的只有事件视界，因为我无法知道它内部发生了什么。
But from the outside, all we should ever really care about is the event horizon, because I can't know what happens to it.
它可能是纯粹的物质和反物质结合在一起，在内部湮灭成光子，所有质量都转化为光的能量。
It could be pure matter and antimatter thrown together, which annihilates into photons on the inside and loses all its mass into the energy of light.
这对我来说无关紧要，因为我无法知道内部发生了什么。
Won't matter to me because I can't know anything about what happened on the inside.
好的。
Okay.
我们能不能就这个话题多停留一会儿？
Can we just, like, linger on this?
那么，关于黑洞内部在那一刻发生的事情，我们有哪些模型呢？
So what models do we have about what happens on the inside of the black hole at that moment?
所以，我想你给我们的一大提醒是，嘿。
So I guess that one of the intuitions, one of the big reminders that you're giving to us is, hey.
我们对黑洞内部可能发生的事情知之甚少，因此我们必须谨慎，最好把黑洞看作是一个事件视界。
We know very little about what can happen on the inside of a black hole, and that's why we have to be careful about making it's better to think about the black hole as an event horizon.
嗯。
Mhmm.
但我们对黑洞内部时空的物理性质能知道什么？又真正知道些什么呢？
But what can we know, and what do we know about the physics of of space time inside a black hole?
我不介意在思考数学告诉我们什么时大胆一些。
I don't mind being incautious about thinking about what the math tells us.
所以，好吧。
So Okay.
我并不是一个观测者。
I'm not such a an observer.
对吧？
Right?
我的工作非常理论化。
I'm very theoretical in my work.
我经常只是用笔在纸上推演。
It's really pen on paper a lot.
这些都是我们可以进行和思考的思想实验。
These are thought experiments that I think we we can perform and contemplate.
我们是否能真正知晓，这是另一个问题。
Whether or not we'll ever know is another question.
因此，我们推测黑洞内部最美妙的现象之一是，空间和时间在某种意义上互换了角色。
And, so one of the most beautiful things that we suspect happens on the inside of a black hole is that space and time, in some sense, swap places.
所以，当我位于黑洞外部时，假设我待在一个舒适的太空站里，这个黑洞的质量可能是太阳的10倍，直径约60公里。
So while I'm on the outside of the black hole, let's say I'm in a nice comfortable space station, this black hole's maybe 10 times the mass of the sun, 60 kilometers across.
我可以距离它100公里远。
I could be a 100 kilometers out.
那已经非常非常近了。
That's very, very close.
嗯。
Mhmm.
安全地绕行着。
Orbiting quite safely.
没什么大不了的。
No big deal.
你知道吗？
You know?
闲逛。
Hanging out.
我不会去打扰黑洞。
I don't bug a black hole.
黑洞也不会打扰我。
Black hole doesn't bug me.
它不会像吸尘器一样把我吸进去，或者发生什么疯狂的事。
It won't suck me up like a vacuum or anything crazy.
但我的一位宇航员朋友跳了进去。
But some my my astronaut friend jumps in.
当他们穿过事件视界时，我作为外部观察者，看到的是黑洞投射出的球形阴影，可能是由周围的光线形成的。
As they cross the event horizon, what I'm calling space I'm looking on the outside at this spherical shadow of the black hole cast by maybe light around it.
这是一个阴影，因为所有靠近的东西都会掉进去。
It's a shadow because everything gets too close, falls in.
这只是一个相对于明亮天空的对比。
It's just this, just contrast against a bright sky.
我想，哦，这里有一个球体的中心，而球体的中心就是奇点。
I think, oh, there's a center of a sphere, And in the center of the sphere is the singularity.
从我的角度来看，它是一个空间中的点。
It's a point in space from my perspective.
但从掉入其中的宇航员的角度来看，它实际上是一个时间点。
But from the perspective of the astronaut who falls in, it's actually a point in time.
所以，他们对空间和时间的概念已经完全旋转了：我称之为朝向黑洞中心的空间方向——就像一个物理球体的中心——他们将会告诉我他们无法告诉我的事，但他们最终会得出结论：哦，不。
So their notions of space and time have rotated so completely that what I'm calling a direction in space towards the center of the black hole, like the center of a physical sphere, they're gonna tell me what they can't tell me, but they're gonna come to the conclusion, oh, no.
那不是一个空间中的位置。
That's not a location in space.
那是一个时间中的位置。
That's a location in time.
换句话说，奇点最终成为了他们的未来，他们无法避开奇点，就像他们无法避开时间的流逝一样。
In other words, the singularity ends up in their future, and they can no more avoid the singularity than they can avoid time coming their way.
所以，一旦你进入黑洞，就没有任何办法可以避开奇点。
So there's no shenanigans you can do once you're inside the black hole to try to skirt it, the singularity.
你无法围绕它进入轨道。
You can't set yourself up in orbit around it.
你无法通过点燃火箭来远离它，因为奇点就在你的未来，你终将不可避免地撞上它。
You can't try to fire rockets and stay away from it because it's in your future, and there's an inevitable moment when you will hit it.
通常，对于恒星质量的黑洞，我们认为这只需要微秒级的时间。
Usually, for a stellar mass black hole, we think it's microseconds.
从事件视界到奇点只需要微秒。
Microseconds to get from the event horizon to the
到奇点。
To the singularity.
到奇点。
To the singularity.
天哪。
Oh, boy.
天啊。
Oh, boy.
所以这是从你宇航员朋友的视角来描述的。
So that's describing from the your astronaut friends' perspective.
是的。
Yes.
从他们的视角来看，奇点就在他们的未来。
From their perspective, the singularities in their future.
但从你的视角来看，当你的朋友掉进黑洞，而你在外围悠闲地观察时，你看到了什么？
But from your perspective, what do you see when your friend falls into the black hole and you're chilling outside and watching?
所以一种思考方式是，当你接近黑洞时，宇航员的时空相对于你的时空在旋转。
So one way to think about this, is to is to think that as you're approaching the black hole, the astronaut's space time is rotating relative to your space time.
比如说，现在我的左边是你的右边。
So let's say right now, my left is your right.
我们并不会对左右方向的这种相对性感到惊讶。
We're not shocked by the fact that there's this relativity in left and right.
嗯。
Mhmm.
这完全能理解。
It's completely understood.
我可以进行空间旋转，使我的左边与你的左边对齐。
And I can perform a spatial rotation to align my left with your left.
现在，我已经完全转到了左边。
Right now, I've completely rotated left
嗯。
Mhmm.
出去。
Out.
对吧？
Right?
如果我想画一个类似地图的方位图，不是指南针图，而是像地图那样，上面有北、南、东、西。
If I just wanna draw a a a kind of a compass diagram not a compass diagram, but, you at the top of maps, there's a north, south, east, west.
但现在，时间是上下方向，而空间的一个方向是东西方向。
But now time is up, down, and one direction of space is, let's say, east west.
当你接近黑洞时，这就像你在时空中旋转，这是一种思考方式。
As you approach the black hole, it's as though you're rotating in space time is one way of thinking about it.
那么，这会带来什么影响呢？
So what is the effect of that?
其影响是，当这位宇航员越来越接近事件视界时，他们空间的一部分被旋转成了我的时间，而他们时间的一部分则被旋转成了我的空间。
The effect of that is as this astronaut gets closer and closer to the event horizon, part of their space is rotated into my time, and part of their time is rotated into my space.
换句话说，他们的时钟看起来与我的时间越来越不同步。
So in other words, their clocks seem to be less aligned with my time.
总体效果是，他们的时间似乎发生了膨胀。
And the overall effect is that their time seems to dilate.
他们手表上的刻度间隔——比如表盘上的滴答声——相对于我的来说被拉长、膨胀了。
The spacing between ticks on the clock of their watch, let's say, on the on the face of their watch, is is elongated, dilated relative to mine.
对我来说，他们的手表似乎走得更慢了，尽管它们和我的手表出自同一家工厂。
And it seems to me that their watches are running slowly even though they were made in the same factory as mine.
它们都被完美地同步过，是出色的瑞士手表。
They were both synchronized beautifully, and they're excellent Swiss watches.
似乎我的同伴的时间流逝得更慢了。
It seems as though time is elapsing more slowly for my companion.
同样，对他们来说，我的时间似乎过得非常快。
And, likewise, for them, it seems like mine's going really fast.
因此，在我的空间站里，可能已经过去了多年。
So years could elapse in my space station.
我的植物来了又走。
My plants come and go.
它们死了。
They die.
我老得更快。
I age faster.
我长出了白发。
I've got gray hair.
嗯。
Mhmm.
他们正在坠入，而在他们的参考系中，已经过去了数分钟。
And they're falling in, and it's been minutes in their frame of reference.
他们那艘小火箭里的花还没有腐烂。
Flowers in their little rocket ship haven't rotted.
他们还没有长出白发。
They don't have gray hair.
他们的生物钟相对于我们的变慢了。
Their biological clocks have slowed down relative to ours.
最终，在事件视界处，这种效应变得极其极端。
Eventually, at the event horizon, it's so extreme.
变得极其缓慢。
It's so slow.
从我的角度来看，他们的时钟仿佛完全停止了。
It's as though their clocks have stopped altogether from my point of view.
这意味着，从我的角度看，他们的时间完全旋转成了我的空间。
And that's to say that it's as though their time is completely rotated into my space.
这与黑洞内部空间和时间互换位置的观点相关。
And this is connected with the idea that inside the black hole space and time have switched places.
因此，我可能会看到他们在那儿悬浮数千年。
So I might see them hover there for millennia.
在我的空间站上，其他宇航员可能已经出生。
Other astronauts could be born on my space station.
几代人可能在那里繁衍生息，注视着这位可怜的宇航员始终未能坠入。
Generations could be populated there watching this poor astronaut never fall in.
所以，基本上，时间几乎停滞了。
So, basically, the time almost comes to a standstill.
嗯。
Mhmm.
但我们仍然知道，他们最终会坠入。
But we still they do fall in.
对。
Right.
他们最终还是会掉进去的。
They do fall in eventually.
这是因为它们自身具有一定的质量。
Now that's because they have some mass of their own.
嗯。
Yeah.
所以它们并不是一个完全无质量的粒子。
So they're not a perfectly light particle.
嗯。
Mhmm.
因此它们会稍微扭曲事件视界。
And so they deform the event horizon a little bit.
你实际上会看到事件视界晃动
You will actually see the event horizon bobble
嗯。
Mhmm.
然后把宇航员吸收进去。
And absorb the astronaut.
所以在有限的时间内，宇航员实际上会坠入其中。
So in some finite time, the astronaut will actually fall in.
所以这就像我们周围一个奇怪的时空气泡。
So so it's like this weird space time bubble that we have around us.
嗯。
Mhmm.
然后黑洞周围有一个巨大的时空弯曲气泡，还伴随着一种漂亮的旋涡状现象。
And then there's a very big space time curvature bubble thing from the black hole, and they there's a nice swirly type situation going on.
嗯。
Yeah.
这就是你被吸进去的方式。
That's how you get sucked up.
嗯。
Yeah.
所以如果你是一个完美的、无限小的粒子，你就会变得
So if you're a perfect, like, infinitely small particle, you would just be
越来越长。
longer and longer.
而且可能就卡在那里什么的，但不，还有量子力学。
And probably just be stuck there or something, but, no, there's quantum mechanics.
嗯。
Mhmm.
最终，你会掉进去。
Eventually, you'll fall in.
任何扰动都只会朝一个方向发展。
Any perturbation will only go one way.
它只在一个方向上是不稳定的。
It's unstable in one direction in one direction only.
但非常重要的是要记住，从宇航员的角度来看，时间根本没有过去多少。
But it's it's really important to remember that from the point of view of the astronaut, not much time has passed at all.
就你而言，你只是轻松地穿越过去，没有任何戏剧性的事件发生，甚至可能根本意识不到自己已经到达了事件视界。
You just sail right across as far as you're concerned, and nothing dramatic happens, or you might not even realize you've come to the event horizon.
你甚至可能根本意识不到自己已经穿越了事件视界，因为那里什么都没有。
You you might not even realize you've crossed the event horizon because it's there's nothing there.
对吧？
Right?
这是一个空无一物的时空区域。
This is an empty region of space time.
没有任何标记能告诉你，你已经到达了这个极其危险的不归点。
There's no marker to tell you you've reached this very dangerous point of no return.
当你在外部时，可以拼命点火推进，或许还能逃脱。
You can fire your rockets like hell when you're on the outside and maybe even escape.
对吧？
Right?
但一旦你到达那个点，无论多少能量都无法拯救你。
But once you get to that point, there's no amount of energy.
宇宙中所有的能量都无法让你免于这场毁灭。
All the energy in the universe will not save you from, this demise.
你知道，黑洞有不同的大小。
You know, there's different sized black holes.
嗯。
Mhmm.
我们能不能谈谈，根据黑洞的大小，你坠入黑洞时的体验会有什么不同？
And maybe can we talk about the experience that you have falling into a black hole depending on what the size of the black hole is?
嗯。
Yeah.
因为据我了解，黑洞越大，坠入其中的体验就越不剧烈。
Because as I understand, if the the the bigger it is, the less drastic the experience of falling into it.
是的。
Yeah.
这可能会让很多人感到惊讶。
That might surprise people.
是的。
Yeah.
黑洞越大，你越不容易察觉自己已经穿过了事件视界。
The bigger it is, the less noticeable it is that you've you've crossed the event horizon.
一种理解方式是，曲率越大，就越不明显。
One way to think about it is curvature is less noticeable the bigger it is.
如果我站在一个篮球上，我会非常清楚地意识到自己正站在一个弯曲的表面上。
So if I'm standing on a basketball, I'm very aware I'm I'm balancing on a curved surface.
我的两只脚位于不同的位置，我能明显感觉到。
I my two feet are in different locations, and I really notice.
但在地球上，你其实需要相当巧妙才能推断出地球是弯曲的。
But on the Earth, you actually have to be kinda clever to deduce that the Earth is curved.
星球越大，你越不容易察觉到它的整体曲率。
The bigger the planet, the less you're gonna notice the curvature, the the global curvature.
黑洞也是同样的道理。
And it's the same thing with a black hole.
一个巨大巨大的黑洞，感觉就像是完全平坦的。
A huge, huge black hole just just kinda feels like just flat.
你根本察觉不到。
You don't really notice.
我正在试图理解其中的物理原理，因为如果你察觉不到的话
I'm trying to figure out how the physic because if you don't notice
那里什么都没有。
And there's nothing there.
但物理规律很奇怪。
But the physics is weird.
在你的参考系中。
In your frame of reference.
不。
No.
还有另一件很酷的事情，我想澄清一下误解。
Also, another cool thing, so I'd like to dispel miss.
嗯。
Yeah.
你需要一分钟吗？
Do you need a minute?
你正抱着头。
You're holding your head.
有一种感觉，你应该能知道什么时候你进入了黑洞，什么时候越过了事件视界。
There's a sense, like, you you should be able to know when you're inside of a black hole, when you've crossed the event horizon.
但不，从你的参考系来看，你可能根本无法察觉。
But, no, from your frame of reference, you might not be able to know.
嗯。
Yeah.
至少一开始，你可能不会意识到发生了什么。
At first, at least, you might not realize what's happened.
有一些线索。
There are some hints.
例如，黑洞从外部看是黑暗的，但内部不一定就是黑暗的。
For instance, black holes are dark from the outside, but they're not necessarily dark on the inside.
所以这很有趣，你的体验可能是非常明亮的
So this is a kind of fascinating that your experience could be that it's quite bright
嗯。
Mhmm.
在黑洞内部，因为来自整个星系的光都从你身后照射进来，并且由于你正朝内部一个高度集中的区域逼近，这些光会聚焦起来。
Inside the black hole because all the light from the galaxy can be shining in behind you, and it's focusing down because you're all approaching this really focused region in the interior.
因此，当你接近奇点时，实际上会看到一道明亮的白光。
And so you actually see a bright white flash of light as you approach the singularity.
你知道，我开玩笑说，这就像一次濒死体验。
You know, I kind of, I joked that it's a, you know, it's like a near death experience.
我们总说隧道尽头有光，而你会看到地球上数千年的时间流逝。
We see the light at the end of the tunnel, so you would see millennia pass on Earth.
你可以看到整个星系的演化，你知道的，就是一道巨大的明亮闪光。
You could see the evolution of, the entire galaxy, you know, one big bright flash of light.
所以这就像濒死体验，但这绝对是彻底的死亡体验。
So it's like a near death experience, but it's definitely a total death experience.
过程非常快，但你向外看，一切都在超快地进行。
It goes pretty fast, but you're looking out you're looking out, everything's going super fast.
是的。
Yeah.
地球和空间站上的时钟相对于你的来说似乎在飞速前进。
The clocks on the Earth, on the space station seem to be progressing very rapidly relative to yours.
光可以追上你，当你看到星系演化展开时，你会看到一道明亮的光束。
The light can catch up to you, and you get this bright beam of light as you see the evolution of the galaxy unfold.
这在一定程度上取决于黑洞的大小以及你能在里面待多久。
And, I mean, it sort of depends on the size of the black hole and how long you have to hang around.
黑洞越大，你到达中心消亡所需的时间就越长。
The bigger the black hole, the longer it takes you to expire in the center.
显然，人类的感觉系统无法正确处理这些信息。
Obviously, the human, sensory system are not able to process that information correctly.
对。
Right.
那会是一微秒，对。
Would be a microsecond and a right.
那也太快了。
That would be too fast.
是的。
Yeah.
但那会很震撼。
But it would be wow.
能获得这些信息真是太酷了。
It'd be so cool to get that information.
但如果是大黑洞，你实际上可以待上几个月。
But a big black hole, you could actually, you know, hang around for some months.
所以是的。
So yeah.
那么小黑洞和超大质量黑洞是如何形成的呢？
What's how are small black holes versus supermassive black holes formed?
只是为了让大家能大致理解一下。
Just so people would kinda load that in.
它们都是恒星形成的吗？
Are they are they all is it always a star?
不是。
No.
所以这也是为什么我们需要更抽象地看待黑洞。
So this is also why it's important to think of black holes more abstractly.
它们是宇宙中非常深刻的存在，可能形成黑洞的方式不止一种。
They are something very profound in the universe, and there are probably multiple ways to make black holes.
通过恒星形成黑洞是最常见的。
Making them with stars is most plentiful.
仅在我们的银河系中，就可能存在数亿甚至多达十亿个黑洞。
There could be hundreds of millions, maybe even a billion black holes in our Milky Way galaxy alone.
这么多恒星。
That many stars.
只有大约1%的恒星会在生命终结时以黑洞的形式死亡。
It's only about 1% of stars that will end their lives in in in a death state that is a black hole.
但我们现在发现，这其实非常令人惊讶，存在着超大质量黑洞。
But we now see, and this was really quite a surprise, that there are supermassive black holes.
它们的质量是太阳的数十亿甚至数百亿倍，达到数百万到数百亿倍太阳质量。
They're billions or even hundreds of billions of times the mass of the sun and, millions to to tens of billions, maybe even hundreds of billions.
因此极其巨大。
So extremely massive.
我们不认为宇宙有足够的时间通过恒星合并来形成这些黑洞。
We don't think that the universe has had enough time to make them from stars that just merge.
我们知道两个黑洞可以合并形成更大的黑洞，而这些更大的黑洞又能继续合并形成更大的黑洞。
We know that two black holes can merge and make a bigger black hole, and then those can merge and make a bigger black hole.
我们认为没有足够的时间来形成它们。
We don't think there's been enough time for that.
因此，人们推测它们在宇宙早期就形成了，可能在大爆炸后几亿年内就直接由原始物质坍缩而成。
So it's suspected that they're formed very early, maybe even a hun a a hundred few hundred million years after the Big Bang, and that they're formed directly by collapsing out of primordial stuff.
嗯。
Mhmm.
直接坍缩形成黑洞。
That there's a direct collapse right into the black hole.
所以在宇宙极早期，这些是来自……
So, like, in the in the very early universe, these are primordial black holes from the
嗯，有
Well, there's
恒星还不是……等等。
stars not quite wait.
你怎么能从那片混沌中立刻形成黑洞呢？
How how do you get from that soup black holes right away?
对。
Right.
所以这很奇怪，但如果你谈论的规模足够大，用密度和空气差不多的物质来形成一个巨大的黑洞反而更容易。
So it's odd, but it's weirdly easier to make a big black hole out of something that's just the density of air, if it's really, really as big as what we're talking about.
因此，在某种意义上，如果它们能在宇宙早期直接坍缩，那么这个过程会更容易发生。
So in some sense, if they're just allowed to directly collapse very early in the universe's history, they can do that more easily.
而且这种现象如此普遍，以至于我们认为每个星系的中心都存在一个这样的超大质量黑洞。
And it's so much so that we think that there's one of these supermassive black holes in the center of every galaxy.
嗯。
Mhmm.
所以它们并不罕见，而且我们知道它们的位置。
So they're not rare, and we know where they are.
它们位于星系的核心。
They're in the nuclei of galaxies.
因此，它们与整个星系的极早期形成以一种令人惊讶且紧密关联的方式绑定在一起。
So they're bound to the very early formation of entire galaxies in a in a really surprising and deeply connected way.
我想知道，就像鸡和蛋的问题一样，超大质量黑洞对星系的形成有多关键、多重要？
I wonder if the, like, the chicken or the egg, is it like, how critical, how essential are the supermassive black holes to the formation of galaxies?
是的。
Yeah.
我的意思是，这还在进行中。
I mean, it's ongoing.
对吧？
Right?
这还在进行中。
It's ongoing.
哪个先出现？
Which came first?
是的。
Yeah.
黑洞还是星系？
The black hole or the galaxy?
可能是早期的大质量恒星，它们只由大爆炸产生的氢和氦组成。
Probably big early stars, which were just made out of hydrogen and helium from the big bang.
当时没有其他任何东西。
There wasn't anything else.
几乎没有其他任何东西。
Not much of anything else.
这些早期恒星正在形成，而黑洞和星系可能就像是围绕它们的气体云。
Those early stars were forming, and then maybe the black holes and kind of the galaxies were like these gassy clouds around them.
但黑洞驱动喷流、喷流将物质吹出星系，从而塑造了星系，或许还抑制了它们的成长，这两者之间可能存在深层关系。
But there's probably a deep relationship between the black hole powering jets, these jets blowing material out of the galaxy that that shaped galaxies, maybe kind of curbed their growth.
因此，我认为我们仍在努力理解这些事件的确切先后顺序。
And so I think the mechanisms are still are still ongoing attempts to understand exactly the ordering of these things.
我们能回到时空的话题吗？
Can we get back to space time?
回到二十世纪初，你是如何想象时空的？
Just going back to the beginning of the twentieth century, how do you imagine space time?
作为人类，我们该如何想象和理解时空呢？在那里，时间只是结合了空间和时间的四维空间中的另一个维度。
How do we, as human beings, supposed to visualize and think about space time where, you know, time is just another dimension in this four d space that combines space and time.
因为我们一直在讨论时空弯曲的各种不同方式。
Because we've been talking about morphing in all kinds of different ways, the curvature of space time.
那么，你该如何去构想它呢？
Like, how do you how are supposed to conceive of it?
你是怎么看待它的？
How do you think of it?
嗯。
Yeah.
时间只是另一个维度。
Time is just another dimension.
我们可以用不同的方式来思考它。
There are different ways we can think about it.
我们可以想象绘制一张空间地图，并将时间视为地图中的另一个方向。
We can imagine drawing a map of space and treating time as another direction in that map.
但我们受到限制，因为作为三维生物，我们无法真正画出四维空间，而这正是我所需要的。
But we're limited because as three-dimensional beings, we can't really draw four dimensions, which is what I'd require.
三个空间维度，因为我很确定至少有三个。
Three spatial, because I'm pretty sure there's at least three.
我认为可能还有更多，但我只愿意讨论大尺度的维度。
I think there's probably more, but, I'm happy just talking about the large dimensions.
我们看到的这三个维度：上和下。
The the three we see up down.
对吧？
Right?
东和西，南和北，三个空间维度。
East west, north south, three three spatial dimensions.
而时间是第四个。
And time is the fourth.
没有人能真正想象出它。
Nobody can really visualize it.
但我们知道如何在纸上用数学方法展开它。
But we know mathematically how to unpack it on paper.
我可以从数学上抑制其中一个空间维度，然后就能很好地画出来。
I can mathematically suppress one of the spatial dimensions, and then I can draw it pretty well.
现在问题是，我们会称之为欧几里得时空。
Now the problem is that we'd call it a Euclidean spacetime.
欧几里得时空是指所有维度都相互正交且被平等对待。
Euclidean spacetime is when all the dimensions are orthogonal and are treated equally.
时间并不是另一个欧几里得维度。
Time is not another Euclidean dimension.
它实际上是闵可夫斯基时空。
It's actually a Minkowski in spacetime.
但这意味着，当我们画出时空时，我们是在错误地表示它，不过这种错误表示是我们深刻理解的。
But it means that the spacetime, we're misrepresenting it when we draw it, but we're misrepresenting it in a way that we deeply understand.
我可以给你举个例子。
I can give you an example.
我可以将地球投影到一张平面上。
The Earth, I can project onto a flat sheet of paper.
我现在正在错误地表示地球的地图。
I am now misrepresenting a map of the Earth.
我知道这一点，但我理解如何在这幅错误的表示中计算距离的规则，因为地球并不是一张平纸。
And I know that, but I understand the rules for how to add distances on this misrepresentation because the Earth is not a flat sheet of paper.
它是一个球体。
It's a sphere.
只要我明白从北极到南极的路径实际上是沿着大圆弧移动，并且我知道这个距离不同于在平纸上测量的距离，我就能很好地利用地图，并理解加法、乘法以及几何规则——这些规则并非基于平纸的几何。
And, and as long as I understand the rules for how I get from the North Pole to the South Pole, that I'm moving along really a great arc, and I understand that the distance is not the distance I would measure on a flat sheet of paper, then I can do a really great job with a map and understanding the rules of addition, multiplication, and the geometries, not the geometry of a flat sheet of paper.
我也可以对时空做同样的事情。
I can do the same thing with space time.
我可以把它画在一张平纸上，但我知道它实际上并不是一个平直的欧几里得空间。
I can draw it on a flat sheet of paper, but I know that it's not actually a flat Euclidean space.
因此，我测量距离的规则与例如笛卡尔几何中的规则不同。
And so my rules for measuring distances are different than the rules I would use that, for instance, Cartesian rules of geometry.
我会知道要使用闵可夫斯基时空的正确规则。
I I would know to use the correct rules for Minkowski spacetime.
这将使我能够计算出两个相对观察者之间经过的时间，现在这相当于地图上的一个时空长度，而我只有使用这些不同的规则才能得到正确的答案。
And and that will allow me to to to to calculate how long, time has elapsed, which is now a kind of a length, a space time length on my map, between two relative observers, and I will get the correct answer, but only if I use these different rules.
那么根据广义相对论，有质量的物体对时空造成了什么影响？
So then what does according to general relativity, objects with mass due to the space time?
对。
Right.
没错。
Exactly.
爱因斯坦为构建这一完全普遍的理论而苦苦探索，而不仅仅是寻求特定的解，比如黑洞、膨胀的时空或星系透镜效应——这些都只是具体的解。
So Einstein struggled for this completely general theory, not a specific solution like a black hole or an expanding space time or galaxies make lenses or those are all solutions.
这就是为什么他的成就如此巨大。
That's why what he did was so enormous.
这是一个完整的范式，认为：这边是物质和能量。
It's an entire paradigm that says, over here is matter and energy.
我要把这叫做方程的右边。
I'm gonna call that the right hand side of the equation.
爱因斯坦方程右边的所有内容，描述了物质和能量在时空中的分布情况。
Everything on the right hand side of Einstein's equations is how matter and energy are distributed in space time.
方程的左边则告诉你，时空如何响应这些物质和能量而发生弯曲，而有些方程根本无法求解。
On the left hand side tells you how space and time deform in response to that matter and energy, and it can be impossible to solve some of those equations.
施瓦西之所以了不起，是因为他在读到这一最终形式后不到一个月，就找到了一个非常优雅简洁的解。
What was so amazing about what Schwarzschild did is he found this very elegant simple solution within, like, a month of reading, this final formulation.
但爱因斯坦并没有去逐一寻找所有的解。
But Einstein didn't go through and try to find all the solutions.
他只是把这交给了我们。
He sort of gave it to us.
对吧？
Right?
他分享了这个理论，此后许多人便争相努力，试图预测：如果我告诉你物质和能量是如何分布的，你就能推断出时空的弯曲程度。
He shared this, and then lots of people since have been scrambling to try to, ah, I can predict the curvature of the spacetime if I tell you how the matter and energy is laid out.
如果所有物质都集中在一个球形系统中，比如太阳甚至黑洞，我就能理解它周围时空的弯曲。
If it's all compact in a spherical system like a sun or even a black hole, I can understand the curves in the spacetime around it.
我可以求出时空的形状。
I can solve for the for the shape of the space time.
我也可以想，如果宇宙中充满了气体或光，并且处处均匀分布，会怎样呢？
I can also say, well, what if the universe is full of gas or light and it's all kind of uniform everywhere?
我会得到一个同样令人惊讶的解，那就是宇宙会因此膨胀，它不是静态的，星系之间的距离会增大。
And I'll find a different equally surprising solution, which is that the universe would expand in response to that, that it's not static, that the distances between galaxies would grow.
这对爱因斯坦来说是一个巨大的惊喜。
This was a huge surprise to Einstein.
因此，他的理论的所有这些推论，你知道，都带来了在他最初提出广义相对论时完全不明显的发现。
So all of these consequences of his theory, you know, came with revelations that were not at all obvious when he first wrote down the general theory.
他不敢认真对待这一理论的后果，这很常见。
And he was afraid to take the consequences of that theory seriously, which is a Often.
这个理论本身在范围、宏伟和力量上都令人畏惧，所以我能理解。
The theory itself in its scope and grandeur and power is scary, so I can understand.
嗯。
Mhmm.
然后就是理论的边缘部分，那里它会失效，理论带来的某些极端后果。
Then there's, you know, the the edges of the theory where it falls apart, the consequences of the theory that are extreme.
很难当真。
It's hard to take seriously.
嗯。
Mhmm.
所以你能某种程度上感同身受。
So you can sort of empathize.
是的。
Yeah.
他非常抗拒宇宙膨胀的观点。
He very much resisted the expansion.
如果你想想1905年，当时他是个25岁、找不到工作的物理学家，却写出了这一系列令人难以置信的论文，关于相对论和量子力学。
So if you think about nineteen o five when he's writing these sequence of unbelievable papers as a 25 year old who can't get a job, you know, as a physicist, and he writes all of these remarkable papers on relativity and quantum mechanics.
甚至在1915年、1916年，他都不知道宇宙中还有其他星系。
And then even in nineteen fifteen, sixteen, he does not know that there are other galaxies out there.
这一点当时并不为人所知。
This this was not known.
人们曾对此进行过推测。
People had mused about it.
天空中有一些模糊的斑块，人们曾对此进行思考。
There were these kind of smudges on the sky that people contemplated.
如果存在其他‘宇宙岛’呢？
What if there are other island universes?
你知道，早在康德时代就有人思考过这个问题，但直到哈勃才...
You know, going back to Kant thought about this, but it wasn't until Hubble.
直到20世纪20年代末，才最终确认了其他星系的存在。
It really wasn't until the late twenties that it's confirmed that there are other galaxies.
哇。
Wow.
是的。
Yeah.
而且他显然没有意识到，我们现在所想的很多东西他都没想过，比如大爆炸。
And he didn't obviously, there's so much we think of now that he didn't think of, so there's no big bang.
对。
Right.
静态宇宙。
Static universe.
但这些都相互关联。
But these are all connected.
哇。
Wow.
是的。
Yeah.
所以他是在信息非常有限的情况下进行思考的。
So he's operating on very little information.
非常少的信息。
Very little information.
这绝对是对的。
That's absolutely true.
实际上，我喜欢指出的一点是，相对论这种观念是以一种文化方式强加给人们的。
Actually, one of the things I like to point out is the idea of relativity was foisted on people in this kind of cultural way.
但你也可以从很多方面称它为一种绝对论的理论。
But there's many ways in which you could call it a theory of absolutism.
而爱因斯坦在信息如此匮乏的情况下得出这一结论，是通过坚持某些非常严格的绝对原则，比如光速的绝对上限和光速的绝对恒定性，这在刚被发现时真的非常古怪。
And, the way Einstein got there with so little information, is by adhering to certain very strict absolutes, like the absolute limit of the speed of light and the absolute constancy of the speed of light, which was completely bizarre when it was first discovered, really.
这是通过实验观察得出的，人们试图弄清楚光的相对速度会是多少。
That was observed through experiments trying to figure out, you know, what would the relative speed of light be.
只有无质量的粒子才具有这种具有绝对速度的特性。
It's the only it's really only massless particles have this property that they have an absolute speed.
如果你仔细想想，这简直不可思议。
And if you think about it, it's incredibly strange.
是的。
Yeah.
真的很奇怪。
It's really strange.
极其奇怪。
Incredibly strange.
从理论角度来看，他认真对待这一点。
And then so so from from theoretical perspective, he he's he takes that seriously.
他非常认真地对待它，而其他人则试图构建模型来消除它，是的。
He takes it very seriously, and everyone else is trying to come up with models to make it go away Yeah.
让光速变得像宇宙中其他一切那样更合理一些。
To make, the speed of light be a little bit more reasonable, like everything else in the universe.
你知道，如果两辆车相向而行，它们的相对速度比其中一辆静止时要快。
You know, if I run at a car, two cars coming at each other, they're coming at each other faster than if one of them stops.
这确实是现实的基本观察。
It's really a basic observation of reality.
对吧？
Right?
这里说，如果我朝着一束光奔跑，而你相对于光源静止，我们会测得完全相同的光速。
Here, this is saying that if I'm racing at a light beam, and you're standing still relative to the source, we'll measure the same exact speed of light.
非常奇怪。
Very strange.
他通过提出一个问题来得出相对论：那么，速度是什么？
And he gets to relativity by saying, well, what speed?
速度就是距离。
Speed is distance.
是空间除以时间。
It's space over time.
是你行进的距离。
It's how far you travel.
是在一定时间内所经过的空间。
It's the space you travel in a certain duration of time.
他说，嗯，那空间和时间一定有什么地方不对。
And he said, well, I bet something must be wrong then with space and time.
这是一个巨大的飞跃。
So this is an enormous leap.
他愿意放弃空间和时间的绝对性，以保持光速不变。
He's willing to give up the absolute character of space and time in favor of keeping the speed of light constant.
他是如何直觉到一个弯曲时空的世界的呢？
How was he able to intuit a world of curved space time.
嗯。
Like Mhmm.
我觉得这是人类历史上最非凡的飞跃之一。
I I think it's like one of the most special leaps Yeah.
在人类历史上。
In human history.
对吧？
Right?
因为这太惊人了。
Because you're It's amazing.
这种飞跃非常、非常、非常困难。
Like, it's very, very, very difficult to make that kind of leap.
我告诉你，我花了很长时间才明白，我不能确切地说出他究竟是怎么做到的。
I'll I'll tell you, it took me, I think, a long time to I can't say this is how he got there exactly.
并不是说我研究过关于他的历史记载或他对内心状态的描述。
It's not as though I studied the historical accounts of or his description of his internal states.
这更多是基于我对这一学科的学习，以及我如何试图用几个简短的步骤告诉别人如何达到这种理解。
This is more having learned the subject, how I try to tell people how to get there in a few short steps.
首先是等效原理，他称之为一生中最幸福的想法。
One is to start with the equivalence principle, which he called the happiest thought of his life.
等效原理在他思考的早期就出现了。
And the equivalence principle comes pretty early on in his thinking.
它始于类似这样的想法。
And and it starts with something like this.
比如现在，我觉得自己正在感受重力，因为我坐在椅子上，能感觉到椅子对我的压力，它阻止了我下坠。
Like, right now, I think I'm feeling gravity because I'm sitting in this chair, and I feel the pressure of the chair, and it's stopping me from falling.
如果躺到床上，我会感觉到身体压在床上的重量。
And, lie down in a bed, I feel heavy on the bed.
我把这种感觉当作重力。
And I think of that as gravity.
爱因斯坦有一种出色的能力，能够剔除所有这些额外因素，包括原子。
And Einstein has a beautiful ability to remove all of these extraneous factors, including atoms.
所以，让我们想象你身处一部电梯里，因为电梯地板在阻止你下落，所以你感到脚部有重量。
So let's imagine instead that you're in an elevator, and you feel heavy on your feet because the floor of the elevator's resisting your fall.
但我想把电梯去掉。
But I wanna remove the elevator.
电梯和重力的基本性质有什么关系呢？
What does the elevator have to do with fundamental properties of gravity?
于是我切断了缆绳。
So I cut the cable.
现在我正在下坠，但电梯也以同样的速度下坠。
Now I'm falling, but the elevator is falling at the same rate as me.
所以现在我在电梯里漂浮着。
So now I'm floating in the elevator.
如果这种情况发生在我身上，如果我醒来时正处于下坠或漂浮的状态，我可能无法分辨自己是在太空中漂浮，还是正在围绕地球下落。
And if this happened to me, if I woke up in this state of falling or floating in the elevator, I might not know if I was in empty space, just floating, or if I was falling around the earth.
实际上，这两种情况是等价的。
There would actually they're equivalent situations.
我无法区分它们的不同。
I would not be able to tell the difference.
当我通过切断缆绳移除电梯时，我实际上正在体验失重状态。
I'm actually when I get rid of the elevator in this way by cutting the cable, I'm actually experiencing weightlessness.
而这种失重正是引力最纯粹的体现。
And that weightlessness is the purest experience of gravity.
因此，这种下坠的概念实际上是根本性的。
And, and so this idea of falling is actually fundamental.
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