Katie Mack: Life-altering questions about the end of the universe | TED

翻译人员: Jennifer Yan 校对人员: Yanyan Hong

莉莉·詹姆斯·奥尔兹（LJO）： 您好，卡蒂，欢迎。

卡蒂·迈克（KM）： 谢谢。谢谢您邀请我。

LJO：很高兴您能来。

我很希望您能给我们这些 不是天体物理学家的人

Lily James Olds: Hi, Katie, welcome.

介绍一下宇宙的起源，

Katie Mack: Thank you. Thanks for having me.

LJO: So happy to have you.

我们又是如何知道这个的。

I would love if, for those of us who are not astrophysicists,

KM：嗯，好的。

其实，我们知道很多 关于早期的宇宙

you could return and help us give a little refresher

on how the universe did begin and how we know that.

和宇宙的起源，

因为我们能看到它。

KM: Right, right, yeah.

So we know actually quite a lot about the early universe,

这是天文学了不起的地方：

about the beginning of the universe,

我们可以看到宇宙的起源。

because we can actually see it.

And this is the wildest part of astronomy,

宇宙现在大概是 138 亿年。

当我们望向宇宙的时候， 我们会看到遥远的星系。

that we can see the beginning of the universe.

So the universe is about 13.8 billion years old,

当我们看那些遥远的星系时， 它们正在远离我们。

and when we look out into the cosmos, we see distant galaxies.

所以很长一段时间 有这样一个观点，

如果星系正在远离我们，

And when we look at the distant ones, they're all moving away from us.

它们以前一定离我们更近。

以前的宇宙一定 在某种意义上更小一些，

And so for a long time, there's been this idea that, well,

if the galaxies are moving away from us now,

更热，更密集，

they must have been closer in the past.

一切都挤在更少的空间里。

The universe in the past must have been smaller in some sense,

这个理念——以前的宇宙 更小，更热，更密集——

这就是大爆炸理论。

hotter and denser,

everything packed into less space.

关于这个理论，在 1960 年代， 我们得到了很直接的证据，

And that's the Big Bang theory,

the idea that the universe was smaller and denser and hotter in the past.

那时我们能够看到

And we got really direct evidence of that in the 1960s

从非常早期的宇宙传来的光。

让我再退一步说。

当我们看一个遥远的星系时，

when we're able to actually see the light

从那个星系发来的光 需要一些时间才能到达我们这里。

from the very early universe.

所以我们会看到一个星系在闪耀。

So let me take one more step back.

那个光有可能用了 十亿年跨越时空，

When we look at a distant galaxy,

the light from that galaxy takes some time to reach us.

从那里到这里。

So we see, you know, we see a galaxy shining.

我们能看到的有些星系， 远到一个程度，

That light might have taken a billion years to cross the space

它的光需要 100 亿年， 甚至 130 亿年，才到达我们这里，

而宇宙本身只有 138 亿年。

between there and here.

We can see galaxies that are so distant

如果你所看的某个东西的光

that the light took 10 billion years, even 13 billion years to reach us,

需要超过 130 亿年

and the universe is only 13.8 billion years old.

才能到达我们这里， 那会发生什么呢？

当你试着看更远的东西时， 又会发生什么呢？

So what happens if you look at something so far away

that the light has taken more than, you know,

其实，你能看多远是有极限的。

more than 13 billion years to reach us?

这个极限就是光需要多久 传到我们这里，

What happens when you try and look at something even farther?

这种极限定义了 什么是“可观测宇宙”。

Well, there's a limit to how far you can look,

如果一样东西远到一个程度，

the observable universe,

它的光需要 150 亿年 才能传到我们这里，

and that limit is defined by how long it takes light to travel.

我们是看不到这个光的， 因为它还没有到达这里。

So if something is so far away

但如果我们看的某种东西远到

that the light would take 15 billion years to reach us,

它的光需要 138 亿年传到我们这里，

we can't see it because the light hasn't gotten here yet.

那我们所看的就正是 宇宙刚刚起源的时候。

But if we look at something that's, you know, so far away,

我们所看的是来自 宇宙刚刚起源时候的光，

the light's taken 13.8 billion years to reach us,

那我们所看见的—— 如果我们看的是那么遥远的东西——

then what we're looking at is a time when the universe was just beginning.

应该就是火吧？

所以我们产生了这个理念： 早期的宇宙

We're looking at the light from the very beginning of the universe

是又热又密集的。

and what we should see, if we look at something that far away,

整个宇宙充满了 一种滚滚的等离子体。

is fire, right?

So we take this idea

如果我们看得足够远， 我们应该看得到它，

that the early universe was hot and dense,

因为我们所看的那个远古的过去

everywhere in the cosmos was, like, filled with this sort of roiling plasma.

早到了整个宇宙都在燃烧。

And so if we look far enough away, we should see it,

令人震惊的是，

because we're looking so far back in time

我们真的看得到这个。

that we're looking at the time when the whole universe was on fire.

当我们用微波望远镜的时候，

And we do see that shockingly,

我们在各个方向 都看到了这种背景光。

we actually do see that.

在我们视线的边缘是热，是火，

When we use microwave telescopes,

we see this background light every direction we look.

而且我们确定它就是热。

我们可以分析光谱，

You know, at the edges of our vision, is this heat, this fire,

并且看到这个微波，

这个辐射，

and we know that it's heat,

跟那种热到发光的东西的光

we can analyze the spectrum of the light

是同一种类的。

所以不论我们向哪个方向看，

and we can see that this microwave light,

this radiation,

如果我们看得足够远， 我们所看到的过去

is the kind of light you get when something is just glowing

遥远到一个程度， 宇宙依然都在燃烧。

because it's hot.

And so we can see that every direction we look,

那就是大爆炸。

if we look far enough away, we’re looking so far back in time

那时到底发生了什么，

that we're seeing a universe that is still on fire.

那个火是怎么起的，

是另一个我们仍在试着搞清楚的 非常复杂的故事。

So that's the Big Bang.

Exactly what happened, you know, around that time,

我们认为在燃烧之前

是一个膨胀， 一个快速的扩大。

how that fire got started,

that's a whole other very complicated story that we're still figuring out.

在那之前，可能有一个奇点。

可能没有，我们不知道。

So we think that, you know,

before the fiery part there was this inflation, this rapid expansion.

我们不知道是什么启动了 那个快速膨胀。

但我们知道，

Before that, maybe there was a singularity,

maybe not, we don't know.

We don't know what started that rapid expansion.

在宇宙的前 38 万年里，

整个空间都充满了这个火，

But we do know that for the first 380,000 years of the cosmos,

我们知道这个是因为我们看得到它。

it was this sort of,

LJO：太神奇了。

让我们来探讨一些

all of space was filled with this fire.

宇宙可能如何终结的精彩细节吧。

And we know that because we can see it.

我知道您跟很多其他宇宙学家 谈论过这个话题，

LJO: It's amazing.

Well, let's get into some of the juicy specifics

关于这个话题有很多不同的理论。

of how exactly the universe might end.

您觉得我们应该从哪里开始？

I know that you've talked to many other cosmologists yourself

您来做主。

等待我们的是什么？

KM：直到如今我们认为最可能， 也是我们在宇宙学里

and there are a lot of different theories on this.

Where do you think we should begin?

最常讲到的一个理论， 叫做“热寂“。

Dealer's choice.

What's in store for us?

KM: Well, so the one that is, as far as we know, the most likely,

这是我在我的TED演讲里讨论过的：

有一种理念是宇宙正在膨胀。

the one that we talk about the most in cosmology, is the heat death.

星系之间的距离变得越来越大。

So this is what I discussed in my TED Talk,

当我们去量宇宙膨胀的时候，

and the idea there is that, you know, the universe is currently expanding.

我们发现它并不在减速，

Galaxies are getting farther and farther apart from each other.

而是在加速。

这有点像如果你把一个球扔向空中，

When we measured the expansion,

it turned out that it was not slowing down at all,

它有一阵儿会减速 然后突然间冲向太空。

it was actually speeding up.

这个例子里所用的物理非常相似，

And that was like if you throw a ball up into the air,

我们以前不知道为什么它会发生。

it slows down for a little while and then just shoots off into space.

现在依然不知道为什么它正在发生。

我们把这个特性称作“暗能量“。

It’s very similar physics,

and we didn't have any idea why that should happen.

我们不知道暗能量是什么。

它好像在把东西推开，

So we still don't know why that's happening.

We attribute it to something we call “dark energy.”

让宇宙加速膨胀。

这个可能会导致

We don't know what dark energy is.

It's just something that seems to be pushing things apart,

所有的东西——

making the universe expand faster.

所有的星系—— 绝然孤立。

And because of that, it looks like we will end up

恒星将死去，

宇宙将变得很暗，很冷。

with everything, really --

基本上，我们最终面临的将是一个

you know, all the galaxies really isolated,

the stars will die away.

又空、又冷、又暗、又孤独的宇宙。

The universe will get very dark, very cold.

这就叫做热寂。

它叫做热寂是因为

And you know, we'll end up with this basically empty,

所有的东西都将衰减成创造的余热。

cold, dark, lonely universe.

都将衰减成创造的余热。

And that's called the heat death.

The reason it's called the heat death

你不可能有一个机器达到 100%的机械效率——

is because, like ...

Everything's decaying into, like, the waste heat of creation.

它总是会通过摩擦失去一点能量。

So, you know, just as you can't have a machine that's perfectly efficient,

这是一个普通的物理概念，

叫做“热力学第二定律”。

it'll always lose a little bit of energy through friction.

所有的东西会衰减成熵—— 成为混乱无序——

That's a property of physics in general,

这是物理对于“热”的概念。

it's called the second law of thermodynamics.

Everything sort of decays into entropy, into disorder,

所以当宇宙里只剩下余热的时候， 这就是热寂。

and that is called heat from a physics perspective.

这也是为什么谈论 其它的可能性很有趣，

因为我们并不确知热寂会发生。

So the heat death is when nothing is left but the waste heat of the universe.

一部分原因是， 我们不知道什么是暗能量。

Which is part of why it's fun to talk about the alternatives,

我们不理解这个让宇宙 加速膨胀的东西。

because we don't know for sure that the heat death will happen.

它有可能只是空间的 一个特质，也就是说，

Partially because we don't know what dark energy is.

空间自然就有这种内置的膨胀，

We don't understand this stuff that's making the universe expand faster.

而且它会这样持续下去。

不过，它也许会随着时间而变化。

Maybe it's just a property of space where, you know,

space just has this sort of, expansion built in,

也许它会逆转， 而在这个大收缩里，

宇宙里所有的东西 都会聚回到原点。

and it'll keep going the way it's going.

或者，它可能会变得更加强大。

But maybe it's something that changes over time.

那样，我们最终面临的 将是“大撕裂”，

Maybe it'll turn around and we'll get a big crunch

也就是说，如果暗能量越变越强，

and everything will come back together.

Or maybe it'll become more powerful.

它不仅仅开始把星系向彼此推开，

And then you end up with something called a “Big Rip,”

而且会把星系里的空间扩大、 让恒星远离星系、

where if the dark energy becomes more powerful,

it starts to not just move galaxies apart from each other,

撕开行星和恒星、

最终毁灭整个宇宙。

but actually expand the space in galaxies and move stars away from galaxies

我在我的书里谈论了这些可能性。

and then pull apart planets and stars

因为我们不知道暗能量是什么，

and eventually destroy the entire universe.

我们不确知它未来会做什么。

So those are other possibilities that I talk about in the book.

LJO：我想提出观众问的几个问题。

Because we don't know what dark energy is,

and we don't know for sure what it'll do in the future.

瓦西里问，

“您有没有问过， ’如果没有宇宙，

LJO: I want to open up to some of the questions from the audience.

那会有什么呢？’

与此连带的问题是， 宇宙终结之后会有什么？”

Vasily asks,

"Have you ever asked the question 'If there were no universe,

KM：我觉得这里的难题就是

what would there be?'

如何定义“宇宙”吧。

This leads to the question of what will be after the universe ends?"

如果你定义宇宙为“所有东西”，

KM: So I think that gets into tricky questions

那么这个问题就不是那么清楚了。

of how do you define universe, right?

“某个东西”和“所有东西”的不同在哪里？

So you can define universe as being everything,

and then it becomes a less clear question.

那么，你知道， 如果有任何其它的东西，

那么根据定义， 它就是宇宙的一部分。

What does it mean for something other than everything?

但是，我们在宇宙学里 谈论宇宙的一种方式

Then, you know, if there is anything else,

it's by definition part of the universe.

是谈论可观测宇宙。

可观测宇宙是宇宙中 我们能看到的部分，

But one of the ways we often talk about the universe in cosmology,

其中，从大爆炸开始， 光有了足够的时间到达我们这里。

is we talk about the observable universe,

我在之前讲过这个。

where the observable universe is the part of the cosmos we can see,

可观测宇宙的边缘是我们看得到 从大爆炸发来的光的地方。

where the light has had time to reach us since the Big Bang.

我们认为实际的宇宙

So I talked about that before.

超出了可观测宇宙的边缘。

The edge of the observable universe is where we see that Big Bang light.

可观测宇宙只是一个视角的问题。

The actual universe,

它有点像地球的地平线：

由于你所处的位置， 你只能看到那么远，

we think extends far beyond the edge of the observable universe.

但是地球延伸到地平线之外。

The observable universe is just a perspective thing.

同样地，我们比较肯定宇宙 比我们能看到和观测到的

It's like a horizon when you're on Earth,

you can only see so far because of where you're standing,

延伸得遥远很多很多。

but the Earth keeps going beyond the horizon.

And similarly, with the universe, we're pretty sure that it extends

不过，我们看得到可观测宇宙，

我们可以研究并且了解它，

much, much farther than what we can see, what we can observe.

而我们却得不到任何 可观测宇宙之外的信息。

所以，就引起， 像多元宇宙这样的观念：

But we can see the observable universe and we can study,

we can learn about the observable universe,

有一些空间区域离我们 远到一个程度，

and we can't get any information about what's beyond it.

它们基本上属于另一个宇宙，

So, you know, that brings up things like a multiverse,

那些区域有完全不同的历史、

where you can have regions of space that are so far away from us

完全不同的未来、

that they’re effectively another universe,

甚至有不同的物理定律。

有多种可能性关于那些

and those regions can have a totally different history,

a totally different future,

在可观测宇宙衰减成熵的时候 继续存在——

different laws of physics even.

So, there are possibilities for things that carry on

或许有别的命运——的东西。

long after our observable universe is decayed into entropy

甚至有可能有

所谓的“高维空间”，

or maybe meets another fate.

有可能有我们不能想象的方向，

And there are even possibilities

比如，一维空间因另一维空间 而与我们隔离。

where there could be higher dimensions of space,

like directions that we can't conceive,

有可能有某一个

我不太能设想的方向

you know, space that's separated from us by some other dimension of space,

不与我们任何的空间方向垂直，

some other direction that we don't, you know,

却在数学上，从某种意义是有道理的。

perpendicular to all of our spatial directions,

所以这方面有诸如此类的可能性。

which I can't sort of envision.

如果你真的深入挖掘，

But mathematically, that makes sense in some ways.

你可能会涉入一些

So there are those kinds of possibilities.

有关时空性质的光怪陆离的东西。

在我的书里，

And you know, you can get into really weird stuff

我只讲了关于我们 可观测的宇宙和它的命运，

about the nature of space and time

with you if you really dig into it.

因为那是我们唯一真的能研究的。

But in the book,

我讲了一点关于多元宇宙

和其它空间部分的可能性。

I really just talk about our observable universe in terms of the fate of that,

但关于我们的宇宙被毁灭以后 会发生什么——

because that's all we can really study.

I do talk a little bit about the multiverse

and the possibilities of other parts of space.

当然，这个取决于它如何被毁灭——

是否当可观测宇宙终结的时候

But in terms of what happens when our universe is destroyed,

有更多的空间在它的边缘以外，

I mean, it depends on how it's destroyed,

这些现在都纯属猜测。

whether there’s, you know, the observable universe is over

LJO：我想稍微转一下话题，

but there's more space beyond it or not.

因为不久前您写了一篇文章

And that's all the realm of speculation at the moment.

关于时空也许不是真的，

LJO: So I want to switch gears a little bit,

宇宙也许有一个更抽象、

because one of the articles that you wrote fairly recently

更数学性质的现实，

talked about how time and space might not be real,

而时空可能只是我们的感知。

and how there might be a deeper,

对此，您能跟我们多分享一些吗？

more abstract mathematical reality to the universe,

这怎么可能？

像在让你的大脑做后空翻。

and that time and space might just be what we perceive.

KM：嗯，这个的确很不可思议。

Can you tell us more about this?

2-3年前，我第一次听到

How is this possible?

Talk about your mind doing backflips.

KM: Yeah, yeah, this is really wild.

有个人在谈论这个：

So I first heard about this a couple of years ago

如果你计算 与其它粒子互动的粒子——

where somebody was talking about how,

有点像在粒子对撞机里

if you do calculations of particles interacting with other particles,

让质子互相撞击

然后测量这对产生 出来的粒子发生了什么，

like the kind of stuff relevant to particle collider experiments

是有办法通过把这些计算

where you're slamming protons into each other

变成一个抽象的数学模式

and measuring what happens to the particles that come out,

there are ways to do those calculations

然后再做计算。

where you can kind of put them into an abstract mathematical format

你得到的答案

跟你用平常的方式计算的一样，

只要真的是粒子在穿过时空

and do the calculation.

与其它粒子在时空里互动。

And then you get the same answer

as if you do the calculation the usual way,

因为有些方法不用空间 或者时间的概念

assuming, you know, it's actually particles moving through space

不用空间或者时间的概念来做计算，

and interacting with each other in space and time.

你只有这种抽象的数学空间，

And since there are ways to do some of these calculations

它从某种意义上意味着 时空不在帮助你，

without making use of the ideas of space or time,

你也不需要它就能理解 这些过程是如何运作的。

you just have this sort of abstract mathematical space,

it sort of suggests that maybe space and time are not helping you

其实在物理中，

有很多东西你可以在 亚原子尺度上计算

and not necessary for understanding how these processes work.

不用空间和时间为重要变量。

And there is actually a lot that you can calculate in physics

它们不是计算的一部分。

而且不用它们的时候， 你会得到正确答案的。

at the sort of, subatomic scale,

where space and time are not salient variables.

这似乎意味着

时间和空间未必是

They're not part of the calculation.

And you get the right answer when you do that.

掌控宇宙如何运行的基础，

And that sort of hints at this idea

你不需要假定所有的事情

that maybe space and time are not the fundamental things

都以一个被时间衡量的空间 为背景而发生。

that govern how the universe works,

如果你跟在这些领域工作，

that you don't have to assume that, you know,

everything happens in a background of a space measured by time.

真的在做这些计算的 理论物理学家谈论，

他们会说，

If you talk to the theoretical physicists who are working in these areas

“是啊，我们多年前就知道

时间和空间不是基本的。”

and are actually doing these calculations, doing these equations,

然后你就说，“等等……什么？”

they will say things like,

LJO：我完全错过了那个信息。

"Oh yeah, we've known for years

that space and time are not fundamental."

KM：嗯，是啊。

And you're like, "Wait, what?"

如果你再深究， 那些理论物理学家会说，

“其实，它们可能只是层展现象。”

LJO: I missed that memo.

好像它们从某种意义上是真的。

KM: Yeah, no, totally.

就像我们活在空间里， 我们体会到时间。

And you dig down into it and they say,

但宇宙的实际构成

"Well, you know, maybe they're emergent."

Maybe it's like, you know, they're sort of real.

是另一种不能很好地映射到

Like, we live in space, we experience time.

But the actual, sort of, fabric of the universe

空间和时间的数学空间。

这个空间不是同一类的东西， 它不遵守同一类的规则。

is some other mathematical space that just doesn't map well

但从某种意义上， 我们可能都是数学性质的，

to space and time.

That's not the same kind of thing, doesn't follow the same kind of rules.

都是数学里的某种实例，

But in some sense, you know, maybe we are mathematical,

而不是在时空里存在的物体。

那才是更基本的东西。

you know, some kind of instantiation of mathematics

我们以为我们看到的是 时空里的物体，

rather than objects in space existing in time.

是因为我们的视角和经历。

And that's the more fundamental thing.

其实，真正组成宇宙的东西不是这些。

And it's just that because of our perspective, because of our experience,

we think we see objects in space and time.

LJO：我很喜欢这个说法。

In fact, that is not what the universe is really made of.

其实，您也是一个诗人。

我不想为难您，

LJO: I love that.

但我特别喜欢您的诗“迷惑”。

You know, it turns out you are also a poet.

我觉得它把这个表达得非常优美。

I don't want to put you on the spot, but I'm wondering,

我在想，您愿不愿意 读一下最后几节？

I really love your poem "Disorientation,"

KM：当然了，没问题。

and I feel like it states this really beautifully, actually.

嗯，这是我几年前写的一首诗，

I was wondering if you'd be willing to read the last few stanzas?

其实是在推特（Twitter）上 发的一个帖子，

KM: Sure, yeah, I can do that.

因为我觉得会挺好玩的。

每一节是一个帖子。

Yes, this was a poem I wrote a few years ago,

它从某种意义上概述了 我是如何看待宇宙的。

and I wrote it as a Twitter thread actually,

just because I thought it would be kind of fun.

这是最后一段。

So each stanza is a tweet.

我想让你相信，这个宇宙是一个 浩瀚、随机、和漠不关心的地方，

But it sort of encapsulates how I think about the universe.

我们的物种和我们的世界 在其中绝不重要。

So, yeah, this is the last bit.

I want you to believe that the universe is a vast, random, uncaring place

我也想让你相信，

我们唯一的回答 就是创造我们自己的美和意义，

in which our species, our world, has absolutely no significance

并且趁着我们能的时候 来分享这美和意义，

我想让你好奇 外面的世界有什么，

And I want you to believe

什么样的梦会在辐射的潮水里涌来，

that the only response is to make our own beauty

and meaning and to share it while we can

跨越一个无止境的广阔长空。

I want to make you wonder what is out there.

我们随着时间将知道的

和那些永远都不会 到达我们的光辉，

What dreams may come in waves of radiation

across the breadth of an endless expanse.

我想让这些在你心中变得有所意义。

What we may know, given time,

就是你在宇宙之中。

and what splendors may never, ever reach us

就是你是宇宙的一份。

就是你诞生于星尘，

I want to make it mean something to you.

也将归于星尘。

就是你是宇宙敬畏自己的一个方式。

That you are in the cosmos.

That you are of the cosmos.

That you were born from stardust

and to stardust you will return.

LJO：我好喜欢啊。

谢谢您，卡蒂。

That you are a way for the universe to be in awe of itself.

谢谢您与我有一个 这么深刻和引人入胜的对话。

我真的不胜荣幸。

LJO: I love that.

Thank you so much, Katie.

Thank you for such a thoughtful and engaging conversation.

It's really been such a pleasure.