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TEDxCaltech

Sean Carroll: Distant time and the hint of a multiverse

肖恩·卡罗尔:遥远的时间与多元宇宙的迹象

Filmed:

在TEDx加州理工学院,宇宙学家肖恩·卡罗尔把我们带入一段娱乐性强且发人深省的,穿梭于时间与宇宙之间的旅程,目的是探究一个貌似简单的问题:为什么存在着时间?潜在的答案指向的对于整个宇宙以及宇宙中的我们的见解足以令人称奇。

- Physicist, cosmologist
A physicist, cosmologist and gifted science communicator, Sean Carroll is asking himself -- and asking us to consider -- questions that get at the fundamental nature of the universe. Full bio

The universe
宇宙
00:15
is really big.
非常大
00:17
We live in a galaxy, the Milky Way Galaxy.
我们生活在一个名为银河的星系
00:19
There are about a hundred billion stars in the Milky Way Galaxy.
银河系中有约一千亿颗恒星
00:22
And if you take a camera
如果你拿起相机
00:25
and you point it at a random part of the sky,
并把它指向空中的任何一处
00:27
and you just keep the shutter open,
打开快门并让它开在那里
00:29
as long as your camera is attached to the Hubble Space Telescope,
只要你的相机接通着哈勃天文望远镜
00:31
it will see something like this.
这就是它会看到的
00:34
Every one of these little blobs
这里的每一小点
00:36
is a galaxy roughly the size of our Milky Way --
都是与我们的银河系大小相当的星系
00:39
a hundred billion stars in each of those blobs.
每一小点中都有一千亿颗恒星
00:41
There are approximately a hundred billion galaxies
而在整个可见宇宙中
00:44
in the observable universe.
约有一千亿个星系
00:47
100 billion is the only number you need to know.
所以你记住一千亿这个数字就行了
00:49
The age of the universe, between now and the Big Bang,
宇宙的年龄 自大爆炸以来
00:51
is a hundred billion in dog years.
在狗看来已过了一千亿年
00:54
(Laughter)
(笑)
00:56
Which tells you something about our place in the universe.
这就告诉了你 我们在这宇宙中的位置
00:58
One thing you can do with a picture like this is simply admire it.
面对这样的画面 你可以做的一件事便是欣赏
01:01
It's extremely beautiful.
它极其美丽
01:03
I've often wondered, what is the evolutionary pressure
我常想 在星系的照片还不存在的时候
01:05
that made our ancestors in the Veldt adapt and evolve
究竟是什么推动了我们远在非洲大草原的祖先
01:08
to really enjoy pictures of galaxies
让他们适应 进化
01:11
when they didn't have any.
并欣赏这些星系的呢?
01:13
But we would also like to understand it.
但除了欣赏 我们也想要了解它们
01:15
As a cosmologist, I want to ask, why is the universe like this?
作为一个宇宙学家 我想问问 宇宙为什么是这样的呢?
01:17
One big clue we have is that the universe is changing with time.
宇宙随着时间流逝的演变 是一条重要的线索
01:21
If you looked at one of these galaxies and measured its velocity,
如果你选中一个星系并测量它的速度
01:24
it would be moving away from you.
你会发现它正离你远去
01:27
And if you look at a galaxy even farther away,
而如果你选中的是一个更远的星系
01:29
it would be moving away faster.
你会发现它正以更快的速度离你远去
01:31
So we say the universe is expanding.
所以说 宇宙正在膨胀
01:33
What that means, of course, is that, in the past,
当然 这就意味着过去所有的一切
01:35
things were closer together.
彼此之间都比较接近
01:37
In the past, the universe was more dense,
曾经的宇宙密度比现在高
01:39
and it was also hotter.
它也比现在热
01:41
If you squeeze things together, the temperature goes up.
如果你把东西紧捏在一切 温度便会上升
01:43
That kind of makes sense to us.
听起来有道理吧
01:45
The thing that doesn't make sense to us as much
而让我们觉得没道理的
01:47
is that the universe, at early times, near the Big Bang,
是宇宙初期 大爆炸之后那个
01:49
was also very, very smooth.
极度光滑的宇宙
01:52
You might think that that's not a surprise.
你或许觉得这并不值得惊讶
01:54
The air in this room is very smooth.
这房间里的空气便十分光滑
01:56
You might say, "Well, maybe things just smoothed themselves out."
你也许会说 “大概这些东西就是会自己慢慢平滑掉的”
01:58
But the conditions near the Big Bang are very, very different
但大爆炸不久之后的环境 与这房间里的空气相比
02:01
than the conditions of the air in this room.
十分 十分的不同
02:04
In particular, things were a lot denser.
特别是一切的密度
02:06
The gravitational pull of things
当时的地心引力
02:08
was a lot stronger near the Big Bang.
比现在强很多
02:10
What you have to think about
我们不得不想想
02:12
is we have a universe with a hundred billion galaxies,
这个宇宙里有一千亿个星系
02:14
a hundred billion stars each.
而每个星系里都有一千亿颗恒星
02:16
At early times, those hundred billion galaxies
在宇宙初期 那一千亿个星系
02:18
were squeezed into a region about this big --
被挤压到这么小的空间
02:21
literally -- at early times.
毫不夸张 当初就这么小
02:24
And you have to imagine doing that squeezing
我们得想象一下这个挤压过程
02:26
without any imperfections,
这个完美的过程
02:28
without any little spots
毫无瑕疵
02:30
where there were a few more atoms than somewhere else.
这里比那里多一两个原子也不行
02:32
Because if there had been, they would have collapsed under the gravitational pull
如果真有任何瑕疵 地心引力也会把它们
02:34
into a huge black hole.
压成一个巨大的黑洞
02:37
Keeping the universe very, very smooth at early times
让初期的宇宙保持在极度光滑的状态并非易事
02:39
is not easy; it's a delicate arrangement.
这是个极为精细的布置
02:42
It's a clue
这条线索意味着初期宇宙
02:44
that the early universe is not chosen randomly.
并非任意选择的产物
02:46
There is something that made it that way.
是某些东西把它造就成那样的
02:48
We would like to know what.
而我们想知道那是什么
02:50
So part of our understanding of this was given to us by Ludwig Boltzmann,
19世纪的奥地利物理学家路德维希·玻尔兹曼
02:52
an Austrian physicist in the 19th century.
给予了我们不少对此的了解
02:55
And Boltzmann's contribution was that he helped us understand entropy.
玻尔兹曼的贡献在于他帮助我们理解了熵
02:58
You've heard of entropy.
你们听见过熵
03:01
It's the randomness, the disorder, the chaoticness of some systems.
在某些系统中 它是随意性 是不规则 是混乱
03:03
Boltzmann gave us a formula --
玻尔兹曼给了我们一条
03:06
engraved on his tombstone now --
被刻在了他墓碑上的公式
03:08
that really quantifies what entropy is.
让我们得以在数量上解释熵
03:10
And it's basically just saying
这条公式所说的 不过是
03:12
that entropy is the number of ways
我们可以重新组合
03:14
we can rearrange the constituents of a system so that you don't notice,
构成一个系统的各个要素 而在宏观上
03:16
so that macroscopically it looks the same.
你看不出任何变化
03:19
If you have the air in this room,
在感受这房间里的空气时
03:21
you don't notice each individual atom.
你不可能注意每一个原子吧
03:23
A low entropy configuration
如果能够组合出某个布局的方式屈指可数
03:26
is one in which there's only a few arrangements that look that way.
那这个布局的熵值就会很小
03:28
A high entropy arrangement
反之 若能组合出某个布局的方式很多
03:30
is one that there are many arrangements that look that way.
这个布局的熵值就会很大
03:32
This is a crucially important insight
对这一点的领悟极其关键
03:34
because it helps us explain
因为它帮助我们解释
03:36
the second law of thermodynamics --
热力学第二定律——
03:38
the law that says that entropy increases in the universe,
在整个宇宙 或是被隔离开的部分宇宙中
03:40
or in some isolated bit of the universe.
熵值只可增大
03:43
The reason why entropy increases
熵值增大的原因很简单
03:45
is simply because there are many more ways
只因呈现出对应于大熵值的布局
03:47
to be high entropy than to be low entropy.
比呈现出对应于小熵值的布局的方式多得多
03:50
That's a wonderful insight,
虽说领会到这些很奇妙
03:52
but it leaves something out.
但还有被遗漏的部分
03:54
This insight that entropy increases, by the way,
值得提及的是 正是熵值的增大
03:56
is what's behind what we call the arrow of time,
推动着我们的时间之箭
03:58
the difference between the past and the future.
造就着过去与未来的不同
04:01
Every difference that there is
过去与未来
04:03
between the past and the future
它们之间的所有区别
04:05
is because entropy is increasing --
都呈现于熵值的增大
04:07
the fact that you can remember the past, but not the future.
正如你能记得往事 却无法去记住将来所要发生的
04:09
The fact that you are born, and then you live, and then you die,
又如你出生 成长 死亡的过程
04:12
always in that order,
这些不变的顺序
04:15
that's because entropy is increasing.
都源于熵值的增大
04:17
Boltzmann explained that if you start with low entropy,
玻尔兹曼解释道 如果你从小熵值出发
04:19
it's very natural for it to increase
它会很自然的增大
04:21
because there's more ways to be high entropy.
因为处于大熵值状态的途径更多
04:23
What he didn't explain
但他并没有解释
04:26
was why the entropy was ever low in the first place.
为什么最初的熵值那么小
04:28
The fact that the entropy of the universe was low
宇宙初期的小熵值
04:31
was a reflection of the fact
意味着的莫过于
04:33
that the early universe was very, very smooth.
初期的宇宙非常非常的光滑
04:35
We'd like to understand that.
而我们想要理解它的原由
04:37
That's our job as cosmologists.
那便是作为宇宙学家的我们的任务
04:39
Unfortunately, it's actually not a problem
遗憾的是 我们并没有
04:41
that we've been giving enough attention to.
给予这个问题多大的关注
04:43
It's not one of the first things people would say,
如果你问一个现代宇宙学家
04:45
if you asked a modern cosmologist,
“我们正研究着的问题有哪些?”
04:47
"What are the problems we're trying to address?"
这不会是回答中你最先听到的问题之一
04:49
One of the people who did understand that this was a problem
认识到这个问题的重要性的其中一人
04:51
was Richard Feynman.
便是理查德·费曼
04:53
50 years ago, he gave a series of a bunch of different lectures.
50年前 他给了一系列的演讲
04:55
He gave the popular lectures
他面向大众的讲座
04:57
that became "The Character of Physical Law."
成了《物理之美》
04:59
He gave lectures to Caltech undergrads
他面向加州理工学院本科生的讲课
05:01
that became "The Feynman Lectures on Physics."
成了《费曼物理学讲义》
05:03
He gave lectures to Caltech graduate students
他面向加州理工学院研究生的讲课
05:05
that became "The Feynman Lectures on Gravitation."
成了《费曼引力学讲义》
05:07
In every one of these books, every one of these sets of lectures,
在上述的每本书 费曼的每个讲座中
05:09
he emphasized this puzzle:
他都强调了这个难题
05:12
Why did the early universe have such a small entropy?
为什么初期的宇宙有着那么小的熵值?
05:14
So he says -- I'm not going to do the accent --
我就不模仿他的口音了
05:17
he says, "For some reason, the universe, at one time,
他说:“虽说宇宙中包含着的能量巨大
05:19
had a very low entropy for its energy content,
某些原因使它曾一度拥有小熵值
05:22
and since then the entropy has increased.
而从那以后 熵值不断增大
05:25
The arrow of time cannot be completely understood
直至我们能够真正理解 而非单单推测
05:27
until the mystery of the beginnings of the history of the universe
整个宇宙历史的 开端的秘密
05:30
are reduced still further
时间之箭
05:33
from speculation to understanding."
便无法被完全理解”
05:35
So that's our job.
这就是我们的使命
05:37
We want to know -- this is 50 years ago, "Surely," you're thinking,
这是费曼50年前说的 你也许在想:“那么久了
05:39
"we've figured it out by now."
我们现在弄清了吧”
05:41
It's not true that we've figured it out by now.
错了 我们到现在也没弄清
05:43
The reason the problem has gotten worse,
非但没把问题弄清
05:45
rather than better,
它还变得更糟糕了
05:47
is because in 1998
因为在1998年
05:49
we learned something crucial about the universe that we didn't know before.
一个关于宇宙的新发型展现在了我们面前
05:51
We learned that it's accelerating.
宇宙不仅在膨胀
05:54
The universe is not only expanding.
而且在加速膨胀
05:56
If you look at the galaxy, it's moving away.
如果你看见一个星系正离你远去
05:58
If you come back a billion years later and look at it again,
十亿年后再回来看它时
06:00
it will be moving away faster.
你会发现它远去的速度加快了
06:02
Individual galaxies are speeding away from us faster and faster
各个星系离我们远去的速度都在不断加快着
06:05
so we say the universe is accelerating.
所以我们说这个宇宙正在加速膨胀
06:08
Unlike the low entropy of the early universe,
与宇宙初期的小熵值不同
06:10
even though we don't know the answer for this,
虽然我们没有答案 但要解释这现象
06:12
we at least have a good theory that can explain it,
我们至少还有一套不错的理论
06:14
if that theory is right,
如果那理论是正确的
06:16
and that's the theory of dark energy.
我是在说暗能量理论
06:18
It's just the idea that empty space itself has energy.
它说 真空区自身便有能量
06:20
In every little cubic centimeter of space,
这空间中的任何一立方厘米中
06:23
whether or not there's stuff,
无论那里有没有东西
06:26
whether or not there's particles, matter, radiation or whatever,
无论那里有没有粒子 物质 辐射 或任何别的什么
06:28
there's still energy, even in the space itself.
那里仍有能量 就这空间中便有
06:30
And this energy, according to Einstein,
在爱因斯坦看来
06:33
exerts a push on the universe.
这能量推动着宇宙
06:35
It is a perpetual impulse
这是一股永恒的冲量
06:38
that pushes galaxies apart from each other.
使各星系之间的距离越来越大
06:40
Because dark energy, unlike matter or radiation,
因为暗能量 与物质和辐射不同
06:42
does not dilute away as the universe expands.
它不会因为宇宙的膨胀而被稀释
06:45
The amount of energy in each cubic centimeter
即便宇宙越来越大
06:48
remains the same,
每立方厘米中的能量
06:50
even as the universe gets bigger and bigger.
都将保持不变
06:52
This has crucial implications
这对宇宙未来的发展
06:54
for what the universe is going to do in the future.
有着关键的影响
06:57
For one thing, the universe will expand forever.
其中之一 便是宇宙会永远膨胀下去
07:00
Back when I was your age,
当我像你们那么小的时候
07:02
we didn't know what the universe was going to do.
我们并不知道宇宙是否会膨胀下去
07:04
Some people thought that the universe would recollapse in the future.
某些人认为 宇宙将会再坍缩
07:06
Einstein was fond of this idea.
爱因斯坦就很喜欢这想法
07:09
But if there's dark energy, and the dark energy does not go away,
但如果有暗能量 而暗能量又会永远留在那里
07:11
the universe is just going to keep expanding forever and ever and ever.
宇宙便会永不停息的 这样膨胀下去
07:14
14 billion years in the past,
从140亿年前
07:17
100 billion dog years,
狗的一千亿年前
07:19
but an infinite number of years into the future.
直至无数年以后 直至永恒的未来
07:21
Meanwhile, for all intents and purposes,
在此期间 不论我们有什么意图或目的
07:24
space looks finite to us.
宇宙空间在我们看来都是有限的
07:27
Space may be finite or infinite,
宇宙或许有限 或许无限
07:29
but because the universe is accelerating,
但因为它正在膨胀
07:31
there are parts of it we cannot see
我们看不到它的某些部分
07:33
and never will see.
也将永远无法看到
07:35
There's a finite region of space that we have access to,
能让我们获取信息的宇宙空间非常有限
07:37
surrounded by a horizon.
它被边界包围着
07:39
So even though time goes on forever,
所以即便时间不停下它的脚步
07:41
space is limited to us.
宇宙空间对我们来说还是有限的
07:43
Finally, empty space has a temperature.
最后 真空区有它的温度
07:45
In the 1970s, Stephen Hawking told us
在70年代 斯蒂芬·霍金告诉我们
07:48
that a black hole, even though you think it's black,
虽然你认为黑洞是黑的
07:50
it actually emits radiation
它其实会辐射
07:52
when you take into account quantum mechanics.
如果把量子力学考虑进去的话
07:54
The curvature of space-time around the black hole
黑洞周围的空间曲率
07:56
brings to life the quantum mechanical fluctuation,
是会导致真空量子涨落的
07:59
and the black hole radiates.
黑洞也就会辐射
08:02
A precisely similar calculation by Hawking and Gary Gibbons
根据霍金与加利·基本斯的 一个类似的精确计算
08:04
showed that if you have dark energy in empty space,
如果真空区里有暗能量
08:07
then the whole universe radiates.
整个宇宙便会辐射
08:10
The energy of empty space
真空区的能量
08:13
brings to life quantum fluctuations.
带来量子涨落
08:15
And so even though the universe will last forever,
所以虽然宇宙是永恒的
08:17
and ordinary matter and radiation will dilute away,
而且一般的物质和辐射会被稀释
08:19
there will always be some radiation,
但某些辐射会永远留下
08:22
some thermal fluctuations,
某些热涨落
08:24
even in empty space.
即便那是真空区
08:26
So what this means
这也就是说
08:28
is that the universe is like a box of gas
宇宙好比一盒气体
08:30
that lasts forever.
永恒的气体
08:32
Well what is the implication of that?
这又意味着什么呢?
08:34
That implication was studied by Boltzmann back in the 19th century.
玻尔兹曼在19世纪对此进行了研究
08:36
He said, well, entropy increases
他说 熵值只会增大
08:39
because there are many, many more ways
因为让宇宙处于大熵值状态的方式
08:42
for the universe to be high entropy, rather than low entropy.
比让它处于小熵值状态的方式 多得多
08:44
But that's a probabilistic statement.
但那是一个概率性的称述
08:47
It will probably increase,
它可能会增大
08:50
and the probability is enormously huge.
而且这可能性奇大无比
08:52
It's not something you have to worry about --
我们不需要担心
08:54
the air in this room all gathering over one part of the room and suffocating us.
这房间里的空气不会挤到一处 并让我们窒息
08:56
It's very, very unlikely.
这可能性极小极小
09:00
Except if they locked the doors
但如果门被锁上
09:02
and kept us here literally forever,
我们被关在这里直至永远
09:04
that would happen.
这便会发生
09:06
Everything that is allowed,
所有被允许的
09:08
every configuration that is allowed to be obtained by the molecules in this room,
这房间里的分子的布局
09:10
would eventually be obtained.
都终究会出现
09:13
So Boltzmann says, look, you could start with a universe
所以玻尔兹曼说 你可以从一个
09:15
that was in thermal equilibrium.
处于热平衡状态的宇宙出发
09:18
He didn't know about the Big Bang. He didn't know about the expansion of the universe.
他没听说过大爆炸 也没听过宇宙膨胀
09:20
He thought that space and time were explained by Isaac Newton --
他以为牛顿对时空做出了充分的解释
09:23
they were absolute; they just stuck there forever.
时空是绝对的 它被永恒的固定在那里
09:26
So his idea of a natural universe
所以他在眼中的自然宇宙里
09:28
was one in which the air molecules were just spread out evenly everywhere --
空气中的分子都平均的分散在各处
09:30
the everything molecules.
所有的分子
09:33
But if you're Boltzmann, you know that if you wait long enough,
但如果你是玻尔兹曼的话 你知道 如果你等的够久
09:35
the random fluctuations of those molecules
那些分子无规则的涨落
09:38
will occasionally bring them
会偶尔使它们
09:41
into lower entropy configurations.
处于小熵值的布局
09:43
And then, of course, in the natural course of things,
但肯定的是 在那之后 随着自然规律
09:45
they will expand back.
它们会涨回到分散的状态
09:47
So it's not that entropy must always increase --
所以说 并非是熵值必须要增大
09:49
you can get fluctuations into lower entropy,
涨落会带来小熵值
09:51
more organized situations.
带来更规则的状态
09:54
Well if that's true,
就这样
09:56
Boltzmann then goes onto invent
玻尔兹曼接着发明了
09:58
two very modern-sounding ideas --
两个听上去很现代化的概念
10:00
the multiverse and the anthropic principle.
多元宇宙与人择原理
10:02
He says, the problem with thermal equilibrium
他说 热平衡的问题在于
10:05
is that we can't live there.
我们无法生活在这样的状态下
10:07
Remember, life itself depends on the arrow of time.
记得吗 生命本身便依赖于时间之箭
10:09
We would not be able to process information,
如果我们生活在热平衡的状态下
10:12
metabolize, walk and talk,
我们将无法处理信息
10:14
if we lived in thermal equilibrium.
没法新陈代谢 没法走路 没法说话
10:16
So if you imagine a very, very big universe,
如果你想象一个很大很大的宇宙
10:18
an infinitely big universe,
一个无限大的宇宙
10:20
with randomly bumping into each other particles,
粒子间无规律的碰撞
10:22
there will occasionally be small fluctuations in the lower entropy states,
会偶尔带来小熵值下的小涨落
10:24
and then they relax back.
然后它们会复原
10:27
But there will also be large fluctuations.
但也会存在大涨落
10:29
Occasionally, you will make a planet
偶然造出个行星
10:31
or a star or a galaxy
恒星 星系
10:33
or a hundred billion galaxies.
或是一千亿个星系
10:35
So Boltzmann says,
所以玻尔兹曼说
10:37
we will only live in the part of the multiverse,
我们只可能生活在多元宇宙里
10:39
in the part of this infinitely big set of fluctuating particles,
这无限大的涨落中的粒子群里
10:42
where life is possible.
允许生命的那部分
10:45
That's the region where entropy is low.
也就是有着小熵值的区域
10:47
Maybe our universe is just one of those things
也许我们宇宙的诞生不过就是
10:49
that happens from time to time.
那些时而发生的事之一
10:52
Now your homework assignment
你们的回家作业
10:54
is to really think about this, to contemplate what it means.
是去好好想想这些 这到底意味着什么
10:56
Carl Sagan once famously said
引用卡尔·萨根的名言
10:58
that "in order to make an apple pie,
“要做个苹果派
11:00
you must first invent the universe."
你必须先造出个宇宙”
11:02
But he was not right.
但他说错了
11:05
In Boltzmann's scenario, if you want to make an apple pie,
根据玻尔兹曼 如果你想要做个苹果派
11:07
you just wait for the random motion of atoms
你只需等着 让原子不规则的运动
11:10
to make you an apple pie.
帮你做个苹果派
11:13
That will happen much more frequently
这比等着原子不规则的运动
11:15
than the random motions of atoms
造出个苹果园
11:17
making you an apple orchard
造出些糖和烤箱
11:19
and some sugar and an oven,
然后再帮你做个苹果派
11:21
and then making you an apple pie.
可能性大得多
11:23
So this scenario makes predictions.
这论点包含着某些预测
11:25
And the predictions are
这些预测包括
11:28
that the fluctuations that make us are minimal.
造出我们的是最小限度的涨落
11:30
Even if you imagine that this room we are in now
即便你想象我们现在的这个房间
11:33
exists and is real and here we are,
真实的存在着 而我们也就在这里
11:36
and we have, not only our memories,
我们不仅有着我们的回忆
11:38
but our impression that outside there's something
也坚信着这房间外面还有东西
11:40
called Caltech and the United States and the Milky Way Galaxy,
有加州理工学院 有美国 有银河系
11:42
it's much easier for all those impressions to randomly fluctuate into your brain
让这些想法通过不规则的涨落进入你的大脑
11:46
than for them actually to randomly fluctuate
比起让这些涨落真正造出加州理工学院
11:49
into Caltech, the United States and the galaxy.
造出美国 造出银河系 要容易得多
11:51
The good news is that,
好消息是
11:54
therefore, this scenario does not work; it is not right.
这论点行不通 是错误的
11:56
This scenario predicts that we should be a minimal fluctuation.
它预测我们应该是个小涨落
11:59
Even if you left our galaxy out,
即便你忽略我们的星系
12:02
you would not get a hundred billion other galaxies.
你也没法弄到一千亿个其他星系
12:04
And Feynman also understood this.
费曼也明白这一点
12:06
Feynman says, "From the hypothesis that the world is a fluctuation,
他说:“假设这世界便是涨落
12:08
all the predictions are that
那这也就意味着 如果我们
12:12
if we look at a part of the world we've never seen before,
对从未观测过的那部分世界进行观测
12:14
we will find it mixed up, and not like the piece we've just looked at --
我们会发现它很混乱 与我们之前观测的
12:16
high entropy.
大熵值的部分不同
12:18
If our order were due to a fluctuation,
如果我们的秩序来自于涨落
12:20
we would not expect order anywhere but where we have just noticed it.
我们便不会认为除了刚注意到的秩序 另外还有秩序
12:22
We therefore conclude the universe is not a fluctuation."
所以我们断定 宇宙并非涨落
12:24
So that's good. The question is then what is the right answer?
这算是好了 但正确的答案又是什么呢?
12:28
If the universe is not a fluctuation,
如果宇宙不是涨落
12:31
why did the early universe have a low entropy?
初期宇宙的熵值为什么那么小?
12:33
And I would love to tell you the answer, but I'm running out of time.
我很乐意回答你 但我没时间了
12:36
(Laughter)
(笑)
12:39
Here is the universe that we tell you about,
我们告诉你的宇宙 对应着
12:41
versus the universe that really exists.
真正存在着的宇宙
12:43
I just showed you this picture.
我刚刚给你们看过这画面
12:45
The universe is expanding for the last 10 billion years or so.
一百多亿年来 宇宙不断膨胀着
12:47
It's cooling off.
它也冷却着
12:49
But we now know enough about the future of the universe
但我们现在对宇宙的了解
12:51
to say a lot more.
足够让我们说出更多的
12:53
If the dark energy remains around,
如果暗能量留在周围不动
12:55
the stars around us will use up their nuclear fuel, they will stop burning.
我们周围的恒星将用尽他们的核子燃料 它们将停止燃烧
12:57
They will fall into black holes.
它们会变成黑洞
13:00
We will live in a universe
我们将生活在一个 除了黑洞
13:02
with nothing in it but black holes.
空空如也的宇宙
13:04
That universe will last 10 to the 100 years --
那宇宙将会存在10的100次方年
13:06
a lot longer than our little universe has lived.
比我们的小宇宙长寿多了
13:10
The future is much longer than the past.
为了比过去长得多
13:12
But even black holes don't last forever.
但就连黑洞也不是永恒的
13:14
They will evaporate,
它们会蒸发
13:16
and we will be left with nothing but empty space.
除了一个真空宇宙我们将一无所有
13:18
That empty space lasts essentially forever.
这真空宇宙将会是永远的
13:20
However, you notice, since empty space gives off radiation,
但你意识到 因为真空区也会有辐射
13:24
there's actually thermal fluctuations,
所以热涨落其实存在着
13:27
and it cycles around
它以存在于真空区中的
13:29
all the different possible combinations
有着各种不同组合的
13:31
of the degrees of freedom that exist in empty space.
自由度之间 不断的循环着
13:33
So even though the universe lasts forever,
所以即便宇宙将永远的存在下去
13:36
there's only a finite number of things
能够在宇宙中发生的事
13:38
that can possibly happen in the universe.
却是有限的
13:40
They all happen over a period of time
它们都在10到10的120次方年
13:42
equal to 10 to the 10 to the 120 years.
这段时间内发生
13:44
So here's two questions for you.
我想问你们两个问题
13:47
Number one: If the universe lasts for 10 to the 10 to the 120 years,
第一:如果宇宙会存在10到10的120次方年
13:49
why are we born
我们为什么出生于
13:52
in the first 14 billion years of it,
最初的140亿年间
13:54
in the warm, comfortable afterglow of the Big Bang?
出生于这大爆炸带来的温暖 舒适的环境中?
13:57
Why aren't we in empty space?
我们为什么不在真空区?
14:00
You might say, "Well there's nothing there to be living,"
你也许会说:“那里根本没有活着的东西”
14:02
but that's not right.
但这不对
14:04
You could be a random fluctuation out of the nothingness.
你可以来自空无一物中无规则的涨落
14:06
Why aren't you?
而你为什么不是呢?
14:08
More homework assignment for you.
还有些回家作业要布置给你们
14:10
So like I said, I don't actually know the answer.
如我所说 我并不知道答案
14:13
I'm going to give you my favorite scenario.
就让我来谈谈我最喜欢的情形吧
14:15
Either it's just like that. There is no explanation.
也许它本该如此 根本没有解释
14:17
This is a brute fact about the universe
这就是个不容争议的关于宇宙的事实
14:20
that you should learn to accept and stop asking questions.
你必须接受它 并不再询问任何问题
14:22
Or maybe the Big Bang
或者说 大爆炸
14:26
is not the beginning of the universe.
并非宇宙的开端
14:28
An egg, an unbroken egg, is a low entropy configuration,
一只完整的鸡蛋 处于小熵值的状态
14:30
and yet, when we open our refrigerator,
但当我们打开冰箱时
14:33
we do not go, "Hah, how surprising to find
我们不会想:“哇 能在冰箱里看到这样一个
14:35
this low entropy configuration in our refrigerator."
小熵值状态实在太惊人了“
14:37
That's because an egg is not a closed system;
那是因为一只鸡蛋并非一个封闭系统
14:39
it comes out of a chicken.
它是某只鸡生出来的
14:42
Maybe the universe comes out of a universal chicken.
也许整个宇宙都是一只宇宙鸡生出来的
14:44
Maybe there is something that naturally,
也许通过物理定律的发展
14:48
through the growth of the laws of physics,
某些东西会自然的导致
14:50
gives rise to universe like ours
这个宇宙
14:53
in low entropy configurations.
以小熵值的形式诞生
14:55
If that's true, it would happen more than once;
如果那是正确的话 它不会只发生一次
14:57
we would be part of a much bigger multiverse.
我们会是巨大的多元宇宙的一部分
14:59
That's my favorite scenario.
这便是我最中意的情形
15:02
So the organizers asked me to end with a bold speculation.
组织者们让我以一个大胆的推测结束我的演讲
15:04
My bold speculation
我大胆的推测
15:07
is that I will be absolutely vindicated by history.
便是我将会绝对的被历史维护
15:09
And 50 years from now,
今后的50年间
15:12
all of my current wild ideas will be accepted as truths
我现在所有疯狂的想法都会
15:14
by the scientific and external communities.
被科学界以及整个社会 接受为现实
15:17
We will all believe that our little universe
我们将全都相信 我们的小宇宙
15:20
is just a small part of a much larger multiverse.
不过是更大的多元宇宙中的一部分
15:22
And even better, we will understand what happened at the Big Bang
不仅如此 我们将理解大爆炸时发生的一切
15:25
in terms of a theory
将有一套能够
15:28
that we will be able to compare to observations.
被观察支持的理论
15:30
This is a prediction. I might be wrong.
这只是预测 我也许错了
15:32
But we've been thinking as a human race
那么多年来 作为人类
15:34
about what the universe was like,
我们不断思考着 曾经的宇宙
15:36
why it came to be in the way it did for many, many years.
是怎样的 而它又是怎么变成它当时的样子的
15:38
It's exciting to think we may finally know the answer someday.
令人兴奋的是 或许终有一天我们会找到答案
15:41
Thank you.
谢谢
15:44
(Applause)
(掌声)
15:46
Translated by Lily Yichen Shi
Reviewed by Jenny Yang

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About the Speaker:

Sean M. Carroll - Physicist, cosmologist
A physicist, cosmologist and gifted science communicator, Sean Carroll is asking himself -- and asking us to consider -- questions that get at the fundamental nature of the universe.

Why you should listen

Sean Carroll is a theoretical physicist at Caltech in Pasadena, California, where he researches theoretical aspects of cosmology, field theory and gravitation -- exploring the nature of fundamental physics by studying the structure and evolution of the universe.

His book on cosmology and the arrow of time, From Eternity to Here: The Quest for the Ultimate Theory of Time, was published in 2010. He keeps a regular blog at Cosmic Variance.

More profile about the speaker
Sean M. Carroll | Speaker | TED.com