TEDxCaltech
Sean Carroll: Distant time and the hint of a multiverse
西恩·凱羅： 遙遠的時間和多重宇宙的徵兆
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在TED加州理工分舵大會，宇宙學家西恩·凱羅以一種有趣並且引人思考的方式，帶領聽眾回顧了時間跟宇宙的屬性，並深入探討了一個貌似很簡單的問題：時間為什麼存在？解釋這個問題，首先需要理解一個令人驚訝的對於宇宙性質的看法，以及對於我們在宇宙中位置的看法。
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. Full bio
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
Double-click the English transcript below to play the video.
00:15
The universe
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宇宙
00:17
is really big.
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是浩瀚的
00:19
We live in a galaxy, the Milky Way Galaxy.
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我們生活在宇宙中的一個星系裡 也就是銀河系
00:22
There are about a hundred billion stars in the Milky Way Galaxy.
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銀河系裡大約有上千億的恆星
00:25
And if you take a camera
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如果你拿一個照相機
00:27
and you point it at a random part of the sky,
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隨便對著天空的某一個角落
00:29
and you just keep the shutter open,
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打開快門
00:31
as long as your camera is attached to the Hubble Space Telescope,
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如果你的照相機連接著一個哈勃天文望遠鏡的話
00:34
it will see something like this.
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你就會看到這樣一幅景象
00:36
Every one of these little blobs
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這一團一團的
00:39
is a galaxy roughly the size of our Milky Way --
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都是是跟銀河系差不多大小的星系
00:41
a hundred billion stars in each of those blobs.
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就是說這枚一團裡都有上千億的恆星
00:44
There are approximately a hundred billion galaxies
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並且在我們可以觀測到的宇宙範圍內
00:47
in the observable universe.
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存在着上千億這樣的團
00:49
100 billion is the only number you need to know.
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上千億——你記住這個數字就可以了
00:51
The age of the universe, between now and the Big Bang,
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宇宙的年齡 也就是從宇宙大爆炸至今
00:54
is a hundred billion in dog years.
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大概是一千億“狗年”（一狗年約等於八年）
00:56
(Laughter)
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（笑聲）
00:58
Which tells you something about our place in the universe.
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我這麼說也是為了告訴你我們在宇宙中的位置
01:01
One thing you can do with a picture like this is simply admire it.
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對於這樣一幅圖像 我們能做什麼呢？也就是純粹的欣賞景仰吧
01:03
It's extremely beautiful.
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多麼美麗的圖像
01:05
I've often wondered, what is the evolutionary pressure
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我時常會想 在星系的圖像還不存在的時候
01:08
that made our ancestors in the Veldt adapt and evolve
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是什麼進化壓力 促使我們非洲大草原的的祖先
01:11
to really enjoy pictures of galaxies
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不斷地適應 進化
01:13
when they didn't have any.
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並開始欣賞星系？
01:15
But we would also like to understand it.
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但是我們還想試圖理解它們
01:17
As a cosmologist, I want to ask, why is the universe like this?
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作為一個宇宙學家 我的疑惑是 為什麼宇宙是這樣的？
01:21
One big clue we have is that the universe is changing with time.
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一個線索就是宇宙是隨著時間而不斷變化的
01:24
If you looked at one of these galaxies and measured its velocity,
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如果你關注一個星系 並度量這個星系變化的速率
01:27
it would be moving away from you.
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你會發現這個星系是不斷離你遠去的
01:29
And if you look at a galaxy even farther away,
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如果你再去關註一個更遠距離以外的星系
01:31
it would be moving away faster.
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這個星系會以更快的速度離你遠去
01:33
So we say the universe is expanding.
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所以我們說宇宙是在不斷膨脹的
01:35
What that means, of course, is that, in the past,
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這是什麼意思呢？就是說 在過去
01:37
things were closer together.
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物質是很緊密的聚合在一起的
01:39
In the past, the universe was more dense,
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在過去 宇宙是相對更加緊實的
01:41
and it was also hotter.
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並且其溫度也更高
01:43
If you squeeze things together, the temperature goes up.
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你把東西擠壓到一起 溫度自然會升高
01:45
That kind of makes sense to us.
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這個很好理解
01:47
The thing that doesn't make sense to us as much
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難以令人理解的是
01:49
is that the universe, at early times, near the Big Bang,
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宇宙在非常早期的時候 也就是大爆炸之後不久
01:52
was also very, very smooth.
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也是非常非常平滑的
01:54
You might think that that's not a surprise.
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你可能想 這沒什麼可驚訝的
01:56
The air in this room is very smooth.
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這個房間裡的空氣就很平滑
01:58
You might say, "Well, maybe things just smoothed themselves out."
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你也許會說 “可能物質自然就平滑了”
02:01
But the conditions near the Big Bang are very, very different
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但是要知道宇宙大爆炸之後初期的情況
02:04
than the conditions of the air in this room.
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與現在這個屋子裡的情況是非常不一樣的
02:06
In particular, things were a lot denser.
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具體來說 就是物質都很緊密
02:08
The gravitational pull of things
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這些物質之間的引力
02:10
was a lot stronger near the Big Bang.
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在大爆炸之後初期比現在要強烈得多
02:12
What you have to think about
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你可以這樣想
02:14
is we have a universe with a hundred billion galaxies,
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我們這個宇宙裡 有上千億的星系
02:16
a hundred billion stars each.
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每個星系裡 有上千億的恆星
02:18
At early times, those hundred billion galaxies
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在很早期的時候 這樣的上千億的星系
02:21
were squeezed into a region about this big --
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被擠壓到了僅僅這樣大小的一個空間裡
02:24
literally -- at early times.
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真的是這樣的 在早期的時候
02:26
And you have to imagine doing that squeezing
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並且 你要知道 這樣的擠壓必須
02:28
without any imperfections,
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以一種完美的方式發生
02:30
without any little spots
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沒有任何一處疏鬆
02:32
where there were a few more atoms than somewhere else.
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即使僅僅是某一處比另一處多了幾個原子
02:34
Because if there had been, they would have collapsed under the gravitational pull
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因為假如有任何疏鬆或不平均的話 整個宇宙就會在引力的作用下垮塌
02:37
into a huge black hole.
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從而變成一個巨大的黑洞
02:39
Keeping the universe very, very smooth at early times
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在宇宙早期保證宇宙處於一個非常平滑的狀態
02:42
is not easy; it's a delicate arrangement.
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是很不容易的 需要精心的安排
02:44
It's a clue
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這就從一個側面說明了
02:46
that the early universe is not chosen randomly.
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早期的宇宙不是一個隨機的組合
02:48
There is something that made it that way.
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有某種原因的存在導致了這樣的組合的發生
02:50
We would like to know what.
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我們研究就是為了明白這種原因
02:52
So part of our understanding of this was given to us by Ludwig Boltzmann,
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路德維希 波茲曼 一個生活在19世紀的奧地利物理學家
02:55
an Austrian physicist in the 19th century.
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向我們提供了部分的解釋
02:58
And Boltzmann's contribution was that he helped us understand entropy.
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波茲曼的貢獻就在於他幫我們理解了“熵”這個概念
03:01
You've heard of entropy.
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你應該聽說過熵
03:03
It's the randomness, the disorder, the chaoticness of some systems.
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熵是指一種存在於某些系統中的隨意性 無序性和混亂性
03:06
Boltzmann gave us a formula --
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波茲曼給出了一個方程式 ——
03:08
engraved on his tombstone now --
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這個方程式現在是刻在他的墓碑上的——
03:10
that really quantifies what entropy is.
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來給熵定量
03:12
And it's basically just saying
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這個方程式大概就是說
03:14
that entropy is the number of ways
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熵是一個值 用來描述在你未發現一個系統
03:16
we can rearrange the constituents of a system so that you don't notice,
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產生了變化的前提下 可以對系統進行重組的方式的數目
03:19
so that macroscopically it looks the same.
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這裡的變化是指外部大體上的變化
03:21
If you have the air in this room,
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比如說這個屋子裡的空氣
03:23
you don't notice each individual atom.
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你不會看到每個原子
03:26
A low entropy configuration
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一個低熵值的形態 是指一個
03:28
is one in which there's only a few arrangements that look that way.
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只能有少數的組合方式的變化來保證外在沒有變化的形態
03:30
A high entropy arrangement
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一個高熵值的組合 是指在這種形態裡
03:32
is one that there are many arrangements that look that way.
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可以有很多種排列組合的方式並不影響其外在沒有變化
03:34
This is a crucially important insight
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這是一個非常重要的見解
03:36
because it helps us explain
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因為這個見解可以幫助我們來解釋
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the second law of thermodynamics --
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熱力學第二定律
03:40
the law that says that entropy increases in the universe,
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這個定律告訴我們 宇宙的熵值在不斷提高
03:43
or in some isolated bit of the universe.
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或是說宇宙各部分的熵值在各自提高
03:45
The reason why entropy increases
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熵值升高的原因很簡單
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is simply because there are many more ways
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那就是高熵值的情況下比在低熵值的情況下
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to be high entropy than to be low entropy.
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存在有更多的可能性
03:52
That's a wonderful insight,
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這是一個很好的觀點
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but it leaves something out.
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但是卻不盡全面
03:56
This insight that entropy increases, by the way,
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順便說一下 這個熵值不斷提高的說法
03:58
is what's behind what we call the arrow of time,
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就是我們說的單向時間軸 時間之箭
04:01
the difference between the past and the future.
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也就是過去與未來的區別
04:03
Every difference that there is
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之所以有這個過去
04:05
between the past and the future
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與現在之間的區別
04:07
is because entropy is increasing --
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原因就是不斷上升的熵值
04:09
the fact that you can remember the past, but not the future.
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你能記住過去的事情 卻不能對未來的事情有印象
04:12
The fact that you are born, and then you live, and then you die,
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你出生 生活 然後死亡
04:15
always in that order,
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這些事情都是依次發生的
04:17
that's because entropy is increasing.
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原因都是熵值在不斷提高
04:19
Boltzmann explained that if you start with low entropy,
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博茨曼解釋說 如果一個初始狀態是低熵值
04:21
it's very natural for it to increase
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很自然的這個狀態會升高到高熵值
04:23
because there's more ways to be high entropy.
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因為這樣就提供了更多種的存在可能性
04:26
What he didn't explain
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但是博茨曼沒有解釋
04:28
was why the entropy was ever low in the first place.
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為什麼低熵值是一個初始狀態
04:31
The fact that the entropy of the universe was low
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宇宙早期的熵值很低
04:33
was a reflection of the fact
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這就反映了
04:35
that the early universe was very, very smooth.
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早期的宇宙是非常平滑的
04:37
We'd like to understand that.
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我們需要理解的就是這一現象
04:39
That's our job as cosmologists.
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我們宇宙學家就是做這個的
04:41
Unfortunately, it's actually not a problem
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可惜的是 我們並沒有給予
04:43
that we've been giving enough attention to.
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這個問題足夠的重視
04:45
It's not one of the first things people would say,
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如果你問一個宇宙學家
04:47
if you asked a modern cosmologist,
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”宇宙學界現在在試圖解決的哪些問題？“
04:49
"What are the problems we're trying to address?"
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這個問題不會是他最先給你的答案之一
04:51
One of the people who did understand that this was a problem
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認識到這個問題的人之一
04:53
was Richard Feynman.
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便是理查德·費曼
04:55
50 years ago, he gave a series of a bunch of different lectures.
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五十年前 他給了一系列講座
04:57
He gave the popular lectures
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他面向大眾的講座
04:59
that became "The Character of Physical Law."
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被編成了一本書 叫做『物理理論的特性』
05:01
He gave lectures to Caltech undergrads
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他給加州理工本科生做的講座
05:03
that became "The Feynman Lectures on Physics."
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變成了『費曼物理講座』一書
05:05
He gave lectures to Caltech graduate students
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他給加州理工研究生做的講座
05:07
that became "The Feynman Lectures on Gravitation."
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被編成了『費曼引力講座』一書
05:09
In every one of these books, every one of these sets of lectures,
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在每本書 每組講座裡
05:12
he emphasized this puzzle:
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費曼都強調了這個難題
05:14
Why did the early universe have such a small entropy?
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為什麼宇宙早期有如此低的一個熵值？
05:17
So he says -- I'm not going to do the accent --
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他說——我就不學他的口音了——
05:19
he says, "For some reason, the universe, at one time,
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他說”出於某種原因 宇宙曾經
05:22
had a very low entropy for its energy content,
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有一個很低的熵值
05:25
and since then the entropy has increased.
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而從那時起 熵值在不斷的升高
05:27
The arrow of time cannot be completely understood
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如果宇宙初期歷史這個謎團
05:30
until the mystery of the beginnings of the history of the universe
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沒有被我們從簡單的揣測
05:33
are reduced still further
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帶入到理解這個層次
05:35
from speculation to understanding."
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我們便無法去完全理解時間之箭”
05:37
So that's our job.
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我們就是要解決這個問題
05:39
We want to know -- this is 50 years ago, "Surely," you're thinking,
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我們想解決——從五十年前開始 你可能會想 ”那肯定
05:41
"we've figured it out by now."
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這個問題現在肯定已經解決了”
05:43
It's not true that we've figured it out by now.
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但事實並非如此
05:45
The reason the problem has gotten worse,
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這個問題現在更難解決了
05:47
rather than better,
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而不是更加容易
05:49
is because in 1998
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原因就是在1998年
05:51
we learned something crucial about the universe that we didn't know before.
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我們對於宇宙有了一個突破性的發現
05:54
We learned that it's accelerating.
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我們了解到了 宇宙是在加速擴張的
05:56
The universe is not only expanding.
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宇宙不僅是在擴張而已
05:58
If you look at the galaxy, it's moving away.
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如果你看著那個星系 他在離你遠去
06:00
If you come back a billion years later and look at it again,
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如果你隔了10億年後再回來看
06:02
it will be moving away faster.
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這個星系會離你更遠
06:05
Individual galaxies are speeding away from us faster and faster
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每個星係都是以加速度不斷離我們遠去的
06:08
so we say the universe is accelerating.
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所以我們說宇宙是在加速擴張的
06:10
Unlike the low entropy of the early universe,
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與早期宇宙低熵值的狀態不同的是
06:12
even though we don't know the answer for this,
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儘管我們不知道為什麼宇宙是在加速擴張的
06:14
we at least have a good theory that can explain it,
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我們有一個還沒有確認的理論
06:16
if that theory is right,
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如果這個理論是正確的話
06:18
and that's the theory of dark energy.
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這就是暗能量理論
06:20
It's just the idea that empty space itself has energy.
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根據這個理論 一個空的空間裡也是有能量的
06:23
In every little cubic centimeter of space,
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在空間的每一個立方厘米裡
06:26
whether or not there's stuff,
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不管有沒有東西存在 都是有能量的
06:28
whether or not there's particles, matter, radiation or whatever,
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不管有沒有粒子 物質 放射 還是別的什麼
06:30
there's still energy, even in the space itself.
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空間 就因為空間本身 也是有能量的
06:33
And this energy, according to Einstein,
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這個能量 愛因斯坦認為
06:35
exerts a push on the universe.
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會對於宇宙施加一個推力
06:38
It is a perpetual impulse
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這個推理是一個永存的推力
06:40
that pushes galaxies apart from each other.
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推動著星系互相遠去
06:42
Because dark energy, unlike matter or radiation,
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這個暗能量 與物質或者放射性不同的是
06:45
does not dilute away as the universe expands.
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不會因為宇宙的擴張而被稀釋
06:48
The amount of energy in each cubic centimeter
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每立方厘米裡能量
06:50
remains the same,
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是不變的
06:52
even as the universe gets bigger and bigger.
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即使宇宙變得越來越大
06:54
This has crucial implications
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這個對於解釋宇宙走向何方
06:57
for what the universe is going to do in the future.
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有很關鍵的意義
07:00
For one thing, the universe will expand forever.
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首先 宇宙將會永遠擴張
07:02
Back when I was your age,
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當我想你們這個年級的時候
07:04
we didn't know what the universe was going to do.
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我們不知道宇宙將會怎樣
07:06
Some people thought that the universe would recollapse in the future.
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有人說宇宙將會又一次垮塌
07:09
Einstein was fond of this idea.
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愛因斯坦很喜歡這個理論
07:11
But if there's dark energy, and the dark energy does not go away,
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但是 如果有暗能量的話 並且它不會消失的話
07:14
the universe is just going to keep expanding forever and ever and ever.
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這個宇宙將不斷 永遠的擴張下去
07:17
14 billion years in the past,
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在過去與的140億年裡
07:19
100 billion dog years,
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也就是一千億狗年
07:21
but an infinite number of years into the future.
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但是我們不能估計未來還有多少年
07:24
Meanwhile, for all intents and purposes,
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同時 不管怎麼看
07:27
space looks finite to us.
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空間對於我們都看起來是有限的
07:29
Space may be finite or infinite,
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空間可能是有限的 也可能是無限的
07:31
but because the universe is accelerating,
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但是因為宇宙是加速度擴張的
07:33
there are parts of it we cannot see
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有一部分宇宙 我們是看不到的
07:35
and never will see.
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並且永遠都看不到
07:37
There's a finite region of space that we have access to,
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我們能夠接觸到的宇宙只是很有限的一部分
07:39
surrounded by a horizon.
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在一個有限的視線範圍之內
07:41
So even though time goes on forever,
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所以即使時間不斷前行
07:43
space is limited to us.
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空間對於我們來說仍然是有限的
07:45
Finally, empty space has a temperature.
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最後 空的空間裡是有一個溫度的
07:48
In the 1970s, Stephen Hawking told us
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在上世紀70年代 史蒂芬·霍金告訴我們
07:50
that a black hole, even though you think it's black,
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黑洞 即使你認為它是黑壓壓的一片
07:52
it actually emits radiation
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也是有放射性的
07:54
when you take into account quantum mechanics.
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如果你從量子力學的角度來考慮問題
07:56
The curvature of space-time around the black hole
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黑洞周圍的時間-空間曲率
07:59
brings to life the quantum mechanical fluctuation,
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帶來了量子力學意義上的波動
08:02
and the black hole radiates.
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並且黑洞開始具有放射性
08:04
A precisely similar calculation by Hawking and Gary Gibbons
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霍金跟加利 吉布森有一個很類似的計算
08:07
showed that if you have dark energy in empty space,
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這個計算顯示 如果你在一個空的空間裡有暗能量
08:10
then the whole universe radiates.
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那麼整個宇宙都是會有放射性的
08:13
The energy of empty space
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空的空間裡的能量
08:15
brings to life quantum fluctuations.
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帶來量子波動
08:17
And so even though the universe will last forever,
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並且即使宇宙永遠存在
08:19
and ordinary matter and radiation will dilute away,
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普通物質跟放射性被稀釋
08:22
there will always be some radiation,
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宇宙中總是會有一些放射性存在的
08:24
some thermal fluctuations,
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還有熱波動
08:26
even in empty space.
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即使是在這樣一個空的空間裡
08:28
So what this means
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這就說明
08:30
is that the universe is like a box of gas
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宇宙就像一個永遠存在的
08:32
that lasts forever.
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装满的气体的盒子
08:34
Well what is the implication of that?
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那麼這說明了什麼呢
08:36
That implication was studied by Boltzmann back in the 19th century.
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博茨曼在19世紀就對此進行了研究
08:39
He said, well, entropy increases
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他說 熵值增加
08:42
because there are many, many more ways
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因為相比起低熵值的狀態
08:44
for the universe to be high entropy, rather than low entropy.
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宇宙有更多方式達到一個高熵值的狀態
08:47
But that's a probabilistic statement.
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但這是一個概率問題
08:50
It will probably increase,
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熵值很有可能升高
08:52
and the probability is enormously huge.
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並且這個可能性是非常巨大的
08:54
It's not something you have to worry about --
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但是你不用擔心說
08:56
the air in this room all gathering over one part of the room and suffocating us.
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這個房間裡所有的空氣將聚集到房間的一個角落 讓我們窒息
09:00
It's very, very unlikely.
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這是非常非常不可能的
09:02
Except if they locked the doors
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除非門被鎖上
09:04
and kept us here literally forever,
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我們真的永遠的在這里呆下去
09:06
that would happen.
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剛才所說的情況才能有可能發生
09:08
Everything that is allowed,
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所有可能發生的情形
09:10
every configuration that is allowed to be obtained by the molecules in this room,
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所有這個屋子裡的原子所可能形成的所有的組合
09:13
would eventually be obtained.
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最後總會被實現
09:15
So Boltzmann says, look, you could start with a universe
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所以博茨曼說 你看 宇宙可以從一個
09:18
that was in thermal equilibrium.
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熱平衡的狀態開始發展
09:20
He didn't know about the Big Bang. He didn't know about the expansion of the universe.
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他不知道宇宙大爆炸理論 更不知道宇宙擴張理論
09:23
He thought that space and time were explained by Isaac Newton --
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他以為牛頓對於時間空間的解釋是正確的 那就是
09:26
they were absolute; they just stuck there forever.
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時間空間是絕對的 永遠不變的
09:28
So his idea of a natural universe
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所以博茨曼的自然宇宙的理論
09:30
was one in which the air molecules were just spread out evenly everywhere --
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認為空氣分子就是平均分散在各處的
09:33
the everything molecules.
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構成各種東西的分子
09:35
But if you're Boltzmann, you know that if you wait long enough,
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但是如果你是博茨曼 你會想 如果你足夠耐心
09:38
the random fluctuations of those molecules
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隨意的分子波動
09:41
will occasionally bring them
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會時不時的把分子
09:43
into lower entropy configurations.
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帶入一個較低熵值的構造
09:45
And then, of course, in the natural course of things,
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當然 之後 按照事物的自然發展規律
09:47
they will expand back.
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分子會重新回到之前的狀態
09:49
So it's not that entropy must always increase --
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所以並不是說熵值必須不斷地增加——
09:51
you can get fluctuations into lower entropy,
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有可能波動使熵值降低
09:54
more organized situations.
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帶來一個更加齊整的情況
09:56
Well if that's true,
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那麼 這個說法是正確的話
09:58
Boltzmann then goes onto invent
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博茨曼進而將會提出
10:00
two very modern-sounding ideas --
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兩個聽起來非常領先的看法
10:02
the multiverse and the anthropic principle.
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多層宇宙和人擇原理
10:05
He says, the problem with thermal equilibrium
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他說 熱平衡狀態的問題是
10:07
is that we can't live there.
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我們無法生活在這個一個平衡的狀態裡
10:09
Remember, life itself depends on the arrow of time.
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你應該還記得 生命本身是依賴於時間軸的存在而存在的
10:12
We would not be able to process information,
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如果在熱平衡的狀態下
10:14
metabolize, walk and talk,
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我們將無法處理信息 新陳代謝
10:16
if we lived in thermal equilibrium.
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走路 說話
10:18
So if you imagine a very, very big universe,
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所以你可能想像一個非常非常大的宇宙
10:20
an infinitely big universe,
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一個無限大的宇宙
10:22
with randomly bumping into each other particles,
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裡面的粒子隨機的互相碰撞
10:24
there will occasionally be small fluctuations in the lower entropy states,
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在這裡宇宙裡將會在較低熵值的狀態中有一些小規模的波動
10:27
and then they relax back.
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然後這些波動會回到原來的狀態
10:29
But there will also be large fluctuations.
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但同時也會有大規模的波動
10:31
Occasionally, you will make a planet
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時不時的 這些波動會造出一個行星來
10:33
or a star or a galaxy
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或者一個恆星 或者一個星系
10:35
or a hundred billion galaxies.
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或者一千億個星系
10:37
So Boltzmann says,
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所以博茨曼說
10:39
we will only live in the part of the multiverse,
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我們只是生活在這個多重宇宙的一個部分裡
10:42
in the part of this infinitely big set of fluctuating particles,
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一個無限大的不斷波動的粒子堆裡的一部分
10:45
where life is possible.
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這部分粒子恰巧有可以有生命存在的條件
10:47
That's the region where entropy is low.
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這個區域也就是有低熵值的一個區域
10:49
Maybe our universe is just one of those things
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可能我們的宇宙 就是偶爾在這個多重宇宙中出現的
10:52
that happens from time to time.
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這麼一個低熵值的宇宙
10:54
Now your homework assignment
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所以 現在我們來佈置家庭作業
10:56
is to really think about this, to contemplate what it means.
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那就是認真想這個問題 到底這個多重宇宙與波動意味著什麼
10:58
Carl Sagan once famously said
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卡爾·薩根曾經提出過一個很有名的說法
11:00
that "in order to make an apple pie,
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那就是 “你要想做一個蘋果派
11:02
you must first invent the universe."
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你必須首先做一個宇宙”
11:05
But he was not right.
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但是他說的不對
11:07
In Boltzmann's scenario, if you want to make an apple pie,
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在博茨曼的假設情況下 如果你想要做一個蘋果派
11:10
you just wait for the random motion of atoms
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你只需要耐心等這些隨機的原子
11:13
to make you an apple pie.
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運動來給你做一個蘋果派
11:15
That will happen much more frequently
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這個要比這些隨即無序的粒子運動
11:17
than the random motions of atoms
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現在給你造出一個蘋果園
11:19
making you an apple orchard
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再給你造出一些糖跟一個火爐
11:21
and some sugar and an oven,
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然後用這些東西給你做一個蘋果派
11:23
and then making you an apple pie.
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更容易發生
11:25
So this scenario makes predictions.
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所以這個假設情況下 我們可以做出一些推測
11:28
And the predictions are
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包括
11:30
that the fluctuations that make us are minimal.
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這些造就了我們的波動是很小的
11:33
Even if you imagine that this room we are in now
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即使你可以想像 這個我們現在所在的屋子
11:36
exists and is real and here we are,
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事實上存在著 真實存在著 並且我們也存在著
11:38
and we have, not only our memories,
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我們不僅有記憶 還有一個感知
11:40
but our impression that outside there's something
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可以知道在我們的存在之外
11:42
called Caltech and the United States and the Milky Way Galaxy,
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還存在著加州理工 美國 銀河系
11:46
it's much easier for all those impressions to randomly fluctuate into your brain
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比起這些東西真正的隨機波動
11:49
than for them actually to randomly fluctuate
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組成加州理工 美國 跟銀河系
11:51
into Caltech, the United States and the galaxy.
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更有可能發生的是你腦子裡的這些印象感知隨意波動
11:54
The good news is that,
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好消息是
11:56
therefore, this scenario does not work; it is not right.
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這個假設情況行不通 是不對的
11:59
This scenario predicts that we should be a minimal fluctuation.
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這個假設情況推測說 我們應該是微微的波動的
12:02
Even if you left our galaxy out,
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即使你不考慮我們的星系
12:04
you would not get a hundred billion other galaxies.
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你也不會得到一千億個其他的星系
12:06
And Feynman also understood this.
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費曼也這樣認為
12:08
Feynman says, "From the hypothesis that the world is a fluctuation,
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費曼說 “假設世界是波動著的
12:12
all the predictions are that
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並且我們的推測都是基於這個想法
12:14
if we look at a part of the world we've never seen before,
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那麼如果我們去觀察一個新的區域
12:16
we will find it mixed up, and not like the piece we've just looked at --
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我們將會發現它是混雜的 不像我們剛剛看到的
12:18
high entropy.
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因為熵值變高了
12:20
If our order were due to a fluctuation,
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如果我們存在秩序基於這個波動
12:22
we would not expect order anywhere but where we have just noticed it.
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那我們將不會在除了剛才看到的那個地方之外找到這種秩序
12:24
We therefore conclude the universe is not a fluctuation."
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這樣 我們就會認為宇宙並不是一個波動的存在
12:28
So that's good. The question is then what is the right answer?
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好的 那麼個問題的答案到底是什麼
12:31
If the universe is not a fluctuation,
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如果宇宙不是一個波動的存在
12:33
why did the early universe have a low entropy?
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為什麼早期宇宙有這樣低的一個熵值
12:36
And I would love to tell you the answer, but I'm running out of time.
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我很樂意告訴你們這個問題的答案 但是我時間不夠了
12:39
(Laughter)
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（笑聲）
12:41
Here is the universe that we tell you about,
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這樣我們就有一個我們給你描述的宇宙 還有
12:43
versus the universe that really exists.
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一個真實存在的宇宙
12:45
I just showed you this picture.
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我剛剛向你描述了這個圖像
12:47
The universe is expanding for the last 10 billion years or so.
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宇宙已經在過去的一百億年中不斷的擴張
12:49
It's cooling off.
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宇宙現在在冷卻下來
12:51
But we now know enough about the future of the universe
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但是我們現在對於宇宙的未來知道的足夠多
12:53
to say a lot more.
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來進行更多的陳述
12:55
If the dark energy remains around,
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如果暗能量還是存在
12:57
the stars around us will use up their nuclear fuel, they will stop burning.
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如果我們周圍的恆星用完它們的核燃料 它們將會停止燃燒
13:00
They will fall into black holes.
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這個恆星那是將會變成黑洞
13:02
We will live in a universe
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我們將會生活在一個·除了黑洞
13:04
with nothing in it but black holes.
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什麼都沒有的宇宙裡
13:06
That universe will last 10 to the 100 years --
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宇宙將會持續存在於這樣的狀態裡大概10的100次方年
13:10
a lot longer than our little universe has lived.
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比我們的小宇宙存在的時間長很多
13:12
The future is much longer than the past.
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未來 比過去 要長很多
13:14
But even black holes don't last forever.
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但是即使是黑洞也不會永遠存在
13:16
They will evaporate,
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他們會蒸發掉
13:18
and we will be left with nothing but empty space.
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然後我們就發現宇宙裡除了空無一物的空間之外 什麼也沒有
13:20
That empty space lasts essentially forever.
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空的空間可以說是永遠存在的
13:24
However, you notice, since empty space gives off radiation,
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但是 你注意到 即使是空的空間 也是有放射性的
13:27
there's actually thermal fluctuations,
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事實上還是有熱波動的
13:29
and it cycles around
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然後如此循環
13:31
all the different possible combinations
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各種不同的在空的空間中存在的
13:33
of the degrees of freedom that exist in empty space.
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不同程度的”空無一物“的組合
13:36
So even though the universe lasts forever,
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所以即使宇宙永遠存在
13:38
there's only a finite number of things
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只有有限的情況
13:40
that can possibly happen in the universe.
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會發生在宇宙裡
13:42
They all happen over a period of time
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這些情況都會發生在
13:44
equal to 10 to the 10 to the 120 years.
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10的10的120次方年的一個時間段裡
13:47
So here's two questions for you.
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我有兩個問題
13:49
Number one: If the universe lasts for 10 to the 10 to the 120 years,
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第一個問題 如果宇宙存在了10的10的120次方年
13:52
why are we born
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為什麼我們人類出現在
13:54
in the first 14 billion years of it,
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初始的一百四十億年裡
13:57
in the warm, comfortable afterglow of the Big Bang?
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在這個溫暖 舒適的宇宙大爆炸的餘輝裡？
14:00
Why aren't we in empty space?
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為什麼我們不是生活在空無一物的空間裡？
14:02
You might say, "Well there's nothing there to be living,"
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你可能會回答說 “那是因為那裡沒有任何東西可以讓我們依賴而生存”
14:04
but that's not right.
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但是 不是這樣的
14:06
You could be a random fluctuation out of the nothingness.
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你可以作為一個隨機的無物的波動的產品
14:08
Why aren't you?
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你為什麼不是這麼一個東西呢？
14:10
More homework assignment for you.
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這就是你們另一個家庭作業
14:13
So like I said, I don't actually know the answer.
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就像我說的 我也不知道答案
14:15
I'm going to give you my favorite scenario.
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我可以告訴你我最喜歡的假設
14:17
Either it's just like that. There is no explanation.
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有一個可能的解釋是 沒有任何解釋
14:20
This is a brute fact about the universe
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關於宇宙的一個很難讓人接受的事實
14:22
that you should learn to accept and stop asking questions.
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就是你必須學會接受現實 停止問問題
14:26
Or maybe the Big Bang
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或者也有可能 宇宙大爆炸
14:28
is not the beginning of the universe.
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並不是宇宙的最初開始
14:30
An egg, an unbroken egg, is a low entropy configuration,
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一個雞蛋 一個完好無損的雞蛋 是一個低熵值的存在
14:33
and yet, when we open our refrigerator,
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然而 我們打開冰箱的時候
14:35
we do not go, "Hah, how surprising to find
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我們不會說 “啊哈 這太令人驚訝了
14:37
this low entropy configuration in our refrigerator."
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我在冰箱裡發現了這麼一個低熵值的玩意”
14:39
That's because an egg is not a closed system;
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因為雞蛋不是一個封閉的系統
14:42
it comes out of a chicken.
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一隻雞下了這個雞蛋
14:44
Maybe the universe comes out of a universal chicken.
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可能宇宙就是一個漁舟雞下的蛋
14:48
Maybe there is something that naturally,
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可能有一東西 很自然的
14:50
through the growth of the laws of physics,
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根據一些物理生長法則
14:53
gives rise to universe like ours
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造就了我們的宇宙
14:55
in low entropy configurations.
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成為一個低熵值的存在
14:57
If that's true, it would happen more than once;
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如果這是真的的話 這樣的情況會發生不止一次
14:59
we would be part of a much bigger multiverse.
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我們會是一個更大的多重宇宙的一部分
15:02
That's my favorite scenario.
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這是我最喜歡的假設
15:04
So the organizers asked me to end with a bold speculation.
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組織者要我以一個大膽的設想來結束我的談話
15:07
My bold speculation
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我的大膽的設想就是
15:09
is that I will be absolutely vindicated by history.
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歷史毫無疑問的將會證明我的理論是無比正確的
15:12
And 50 years from now,
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從現在起 五十年後
15:14
all of my current wild ideas will be accepted as truths
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我現在的所有瘋狂的理論都會被奉為是真理
15:17
by the scientific and external communities.
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不僅是在科學界 也包括在社會上
15:20
We will all believe that our little universe
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我們都會相信我們的小小宇宙
15:22
is just a small part of a much larger multiverse.
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只是一個更大的多重宇宙的一小部分
15:25
And even better, we will understand what happened at the Big Bang
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還有更好的 在理論層面上
15:28
in terms of a theory
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我們將會理解宇宙大爆炸的時候發生了什麼
15:30
that we will be able to compare to observations.
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我們就可以跟我們的觀察結果做對比
15:32
This is a prediction. I might be wrong.
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這只是一個推測 我可能猜錯
15:34
But we've been thinking as a human race
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但是人類已經思考了很多年
15:36
about what the universe was like,
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為什麼宇宙是現在這樣的
15:38
why it came to be in the way it did for many, many years.
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為什麼它變成現在這樣樣子
15:41
It's exciting to think we may finally know the answer someday.
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令人激動的是 我們可能會在某一天終於找到答案
15:44
Thank you.
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謝謝大家
15:46
(Applause)
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（掌聲）
ABOUT THE SPEAKER
Sean M. Carroll - Physicist, cosmologistA 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.
Sean M. Carroll | Speaker | TED.com