Sean Carroll: Distant time and the hint of a multiverse

譯者: Yakun Li 審譯者: Lily Yichen Shi

The universe

宇宙

is really big.

是浩瀚的

We live in a galaxy, the Milky Way Galaxy.

我們生活在宇宙中的一個星系裡 也就是銀河系

There are about a hundred billion stars in the Milky Way Galaxy.

銀河系裡大約有上千億的恆星

And if you take a camera

如果你拿一個照相機

and you point it at a random part of the sky,

隨便對著天空的某一個角落

and you just keep the shutter open,

打開快門

as long as your camera is attached to the Hubble Space Telescope,

如果你的照相機連接著一個哈勃天文望遠鏡的話

it will see something like this.

你就會看到這樣一幅景象

Every one of these little blobs

這一團一團的

is a galaxy roughly the size of our Milky Way --

都是是跟銀河系差不多大小的星系

a hundred billion stars in each of those blobs.

就是說這枚一團裡都有上千億的恆星

There are approximately a hundred billion galaxies

並且在我們可以觀測到的宇宙範圍內

in the observable universe.

存在着上千億這樣的團

100 billion is the only number you need to know.

上千億——你記住這個數字就可以了

The age of the universe, between now and the Big Bang,

宇宙的年齡 也就是從宇宙大爆炸至今

is a hundred billion in dog years.

大概是一千億“狗年”（一狗年約等於八年）

(Laughter)

（笑聲）

Which tells you something about our place in the universe.

我這麼說也是為了告訴你我們在宇宙中的位置

One thing you can do with a picture like this is simply admire it.

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

It's extremely beautiful.

多麼美麗的圖像

I've often wondered, what is the evolutionary pressure

我時常會想 在星系的圖像還不存在的時候

that made our ancestors in the Veldt adapt and evolve

是什麼進化壓力 促使我們非洲大草原的的祖先

to really enjoy pictures of galaxies

不斷地適應 進化

when they didn't have any.

並開始欣賞星系？

But we would also like to understand it.

但是我們還想試圖理解它們

As a cosmologist, I want to ask, why is the universe like this?

作為一個宇宙學家 我的疑惑是 為什麼宇宙是這樣的？

One big clue we have is that the universe is changing with time.

一個線索就是宇宙是隨著時間而不斷變化的

If you looked at one of these galaxies and measured its velocity,

如果你關注一個星系 並度量這個星系變化的速率

it would be moving away from you.

你會發現這個星系是不斷離你遠去的

And if you look at a galaxy even farther away,

如果你再去關註一個更遠距離以外的星系

it would be moving away faster.

這個星系會以更快的速度離你遠去

So we say the universe is expanding.

所以我們說宇宙是在不斷膨脹的

What that means, of course, is that, in the past,

這是什麼意思呢？就是說 在過去

things were closer together.

物質是很緊密的聚合在一起的

In the past, the universe was more dense,

在過去 宇宙是相對更加緊實的

and it was also hotter.

並且其溫度也更高

If you squeeze things together, the temperature goes up.

你把東西擠壓到一起 溫度自然會升高

That kind of makes sense to us.

這個很好理解

The thing that doesn't make sense to us as much

難以令人理解的是

is that the universe, at early times, near the Big Bang,

宇宙在非常早期的時候 也就是大爆炸之後不久

was also very, very smooth.

也是非常非常平滑的

You might think that that's not a surprise.

你可能想 這沒什麼可驚訝的

The air in this room is very smooth.

這個房間裡的空氣就很平滑

You might say, "Well, maybe things just smoothed themselves out."

你也許會說 “可能物質自然就平滑了”

But the conditions near the Big Bang are very, very different

但是要知道宇宙大爆炸之後初期的情況

than the conditions of the air in this room.

與現在這個屋子裡的情況是非常不一樣的

In particular, things were a lot denser.

具體來說 就是物質都很緊密

The gravitational pull of things

這些物質之間的引力

was a lot stronger near the Big Bang.

在大爆炸之後初期比現在要強烈得多

What you have to think about

你可以這樣想

is we have a universe with a hundred billion galaxies,

我們這個宇宙裡 有上千億的星系

a hundred billion stars each.

每個星系裡 有上千億的恆星

At early times, those hundred billion galaxies

在很早期的時候 這樣的上千億的星系

were squeezed into a region about this big --

被擠壓到了僅僅這樣大小的一個空間裡

literally -- at early times.

真的是這樣的 在早期的時候

And you have to imagine doing that squeezing

並且 你要知道 這樣的擠壓必須

without any imperfections,

以一種完美的方式發生

without any little spots

沒有任何一處疏鬆

where there were a few more atoms than somewhere else.

即使僅僅是某一處比另一處多了幾個原子

Because if there had been, they would have collapsed under the gravitational pull

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

into a huge black hole.

從而變成一個巨大的黑洞

Keeping the universe very, very smooth at early times

在宇宙早期保證宇宙處於一個非常平滑的狀態

is not easy; it's a delicate arrangement.

是很不容易的 需要精心的安排

It's a clue

這就從一個側面說明了

that the early universe is not chosen randomly.

早期的宇宙不是一個隨機的組合

There is something that made it that way.

有某種原因的存在導致了這樣的組合的發生

We would like to know what.

我們研究就是為了明白這種原因

So part of our understanding of this was given to us by Ludwig Boltzmann,

路德維希 波茲曼 一個生活在19世紀的奧地利物理學家

an Austrian physicist in the 19th century.

向我們提供了部分的解釋

And Boltzmann's contribution was that he helped us understand entropy.

波茲曼的貢獻就在於他幫我們理解了“熵”這個概念

You've heard of entropy.

你應該聽說過熵

It's the randomness, the disorder, the chaoticness of some systems.

熵是指一種存在於某些系統中的隨意性 無序性和混亂性

Boltzmann gave us a formula --

波茲曼給出了一個方程式 ——

engraved on his tombstone now --

這個方程式現在是刻在他的墓碑上的——

that really quantifies what entropy is.

來給熵定量

And it's basically just saying

這個方程式大概就是說

that entropy is the number of ways

熵是一個值 用來描述在你未發現一個系統

we can rearrange the constituents of a system so that you don't notice,

產生了變化的前提下 可以對系統進行重組的方式的數目

so that macroscopically it looks the same.

這裡的變化是指外部大體上的變化

If you have the air in this room,

比如說這個屋子裡的空氣

you don't notice each individual atom.

你不會看到每個原子

A low entropy configuration

一個低熵值的形態 是指一個

is one in which there's only a few arrangements that look that way.

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

A high entropy arrangement

一個高熵值的組合 是指在這種形態裡

is one that there are many arrangements that look that way.

可以有很多種排列組合的方式並不影響其外在沒有變化

This is a crucially important insight

這是一個非常重要的見解

because it helps us explain

因為這個見解可以幫助我們來解釋

the second law of thermodynamics --

熱力學第二定律

the law that says that entropy increases in the universe,

這個定律告訴我們 宇宙的熵值在不斷提高

or in some isolated bit of the universe.

或是說宇宙各部分的熵值在各自提高

The reason why entropy increases

熵值升高的原因很簡單

is simply because there are many more ways

那就是高熵值的情況下比在低熵值的情況下

to be high entropy than to be low entropy.

存在有更多的可能性

That's a wonderful insight,

這是一個很好的觀點

but it leaves something out.

但是卻不盡全面

This insight that entropy increases, by the way,

順便說一下 這個熵值不斷提高的說法

is what's behind what we call the arrow of time,

就是我們說的單向時間軸 時間之箭

the difference between the past and the future.

也就是過去與未來的區別

Every difference that there is

之所以有這個過去

between the past and the future

與現在之間的區別

is because entropy is increasing --

原因就是不斷上升的熵值

the fact that you can remember the past, but not the future.

你能記住過去的事情 卻不能對未來的事情有印象

The fact that you are born, and then you live, and then you die,

你出生 生活 然後死亡

always in that order,

這些事情都是依次發生的

that's because entropy is increasing.

原因都是熵值在不斷提高

Boltzmann explained that if you start with low entropy,

博茨曼解釋說 如果一個初始狀態是低熵值

it's very natural for it to increase

很自然的這個狀態會升高到高熵值

because there's more ways to be high entropy.

因為這樣就提供了更多種的存在可能性

What he didn't explain

但是博茨曼沒有解釋

was why the entropy was ever low in the first place.

為什麼低熵值是一個初始狀態

The fact that the entropy of the universe was low

宇宙早期的熵值很低

was a reflection of the fact

這就反映了

that the early universe was very, very smooth.

早期的宇宙是非常平滑的

We'd like to understand that.

我們需要理解的就是這一現象

That's our job as cosmologists.

我們宇宙學家就是做這個的

Unfortunately, it's actually not a problem

可惜的是 我們並沒有給予

that we've been giving enough attention to.

這個問題足夠的重視

It's not one of the first things people would say,

如果你問一個宇宙學家

if you asked a modern cosmologist,

”宇宙學界現在在試圖解決的哪些問題？“

"What are the problems we're trying to address?"

這個問題不會是他最先給你的答案之一

One of the people who did understand that this was a problem

認識到這個問題的人之一

was Richard Feynman.

便是理查德·費曼

50 years ago, he gave a series of a bunch of different lectures.

五十年前 他給了一系列講座

He gave the popular lectures

他面向大眾的講座

that became "The Character of Physical Law."

被編成了一本書 叫做『物理理論的特性』

He gave lectures to Caltech undergrads

他給加州理工本科生做的講座

that became "The Feynman Lectures on Physics."

變成了『費曼物理講座』一書

He gave lectures to Caltech graduate students

他給加州理工研究生做的講座

that became "The Feynman Lectures on Gravitation."

被編成了『費曼引力講座』一書

In every one of these books, every one of these sets of lectures,

在每本書 每組講座裡

he emphasized this puzzle:

費曼都強調了這個難題

Why did the early universe have such a small entropy?

為什麼宇宙早期有如此低的一個熵值？

So he says -- I'm not going to do the accent --

他說——我就不學他的口音了——

he says, "For some reason, the universe, at one time,

他說”出於某種原因 宇宙曾經

had a very low entropy for its energy content,

有一個很低的熵值

and since then the entropy has increased.

而從那時起 熵值在不斷的升高

The arrow of time cannot be completely understood

如果宇宙初期歷史這個謎團

until the mystery of the beginnings of the history of the universe

沒有被我們從簡單的揣測

are reduced still further

帶入到理解這個層次

from speculation to understanding."

我們便無法去完全理解時間之箭”

So that's our job.

我們就是要解決這個問題

We want to know -- this is 50 years ago, "Surely," you're thinking,

我們想解決——從五十年前開始　你可能會想 ”那肯定

"we've figured it out by now."

這個問題現在肯定已經解決了”

It's not true that we've figured it out by now.

但事實並非如此

The reason the problem has gotten worse,

這個問題現在更難解決了

rather than better,

而不是更加容易

is because in 1998

原因就是在1998年

we learned something crucial about the universe that we didn't know before.

我們對於宇宙有了一個突破性的發現

We learned that it's accelerating.

我們了解到了 宇宙是在加速擴張的

The universe is not only expanding.

宇宙不僅是在擴張而已

If you look at the galaxy, it's moving away.

如果你看著那個星系 他在離你遠去

If you come back a billion years later and look at it again,

如果你隔了10億年後再回來看

it will be moving away faster.

這個星系會離你更遠

Individual galaxies are speeding away from us faster and faster

每個星係都是以加速度不斷離我們遠去的

so we say the universe is accelerating.

所以我們說宇宙是在加速擴張的

Unlike the low entropy of the early universe,

與早期宇宙低熵值的狀態不同的是

even though we don't know the answer for this,

儘管我們不知道為什麼宇宙是在加速擴張的

we at least have a good theory that can explain it,

我們有一個還沒有確認的理論

if that theory is right,

如果這個理論是正確的話

and that's the theory of dark energy.

這就是暗能量理論

It's just the idea that empty space itself has energy.

根據這個理論 一個空的空間裡也是有能量的

In every little cubic centimeter of space,

在空間的每一個立方厘米裡

whether or not there's stuff,

不管有沒有東西存在 都是有能量的

whether or not there's particles, matter, radiation or whatever,

不管有沒有粒子 物質 放射 還是別的什麼

there's still energy, even in the space itself.

空間 就因為空間本身 也是有能量的

And this energy, according to Einstein,

這個能量 愛因斯坦認為

exerts a push on the universe.

會對於宇宙施加一個推力

It is a perpetual impulse

這個推理是一個永存的推力

that pushes galaxies apart from each other.

推動著星系互相遠去

Because dark energy, unlike matter or radiation,

這個暗能量 與物質或者放射性不同的是

does not dilute away as the universe expands.

不會因為宇宙的擴張而被稀釋

The amount of energy in each cubic centimeter

每立方厘米裡能量

remains the same,

是不變的

even as the universe gets bigger and bigger.

即使宇宙變得越來越大

This has crucial implications

這個對於解釋宇宙走向何方

for what the universe is going to do in the future.

有很關鍵的意義

For one thing, the universe will expand forever.

首先 宇宙將會永遠擴張

Back when I was your age,

當我想你們這個年級的時候

we didn't know what the universe was going to do.

我們不知道宇宙將會怎樣

Some people thought that the universe would recollapse in the future.

有人說宇宙將會又一次垮塌

Einstein was fond of this idea.

愛因斯坦很喜歡這個理論

But if there's dark energy, and the dark energy does not go away,

但是 如果有暗能量的話 並且它不會消失的話

the universe is just going to keep expanding forever and ever and ever.

這個宇宙將不斷 永遠的擴張下去

14 billion years in the past,

在過去與的140億年裡

100 billion dog years,

也就是一千億狗年

but an infinite number of years into the future.

但是我們不能估計未來還有多少年

Meanwhile, for all intents and purposes,

同時 不管怎麼看

space looks finite to us.

空間對於我們都看起來是有限的

Space may be finite or infinite,

空間可能是有限的 也可能是無限的

but because the universe is accelerating,

但是因為宇宙是加速度擴張的

there are parts of it we cannot see

有一部分宇宙 我們是看不到的

and never will see.

並且永遠都看不到

There's a finite region of space that we have access to,

我們能夠接觸到的宇宙只是很有限的一部分

surrounded by a horizon.

在一個有限的視線範圍之內

So even though time goes on forever,

所以即使時間不斷前行

space is limited to us.

空間對於我們來說仍然是有限的

Finally, empty space has a temperature.

最後 空的空間裡是有一個溫度的

In the 1970s, Stephen Hawking told us

在上世紀70年代 史蒂芬·霍金告訴我們

that a black hole, even though you think it's black,

黑洞 即使你認為它是黑壓壓的一片

it actually emits radiation

也是有放射性的

when you take into account quantum mechanics.

如果你從量子力學的角度來考慮問題

The curvature of space-time around the black hole

黑洞周圍的時間-空間曲率

brings to life the quantum mechanical fluctuation,

帶來了量子力學意義上的波動

and the black hole radiates.

並且黑洞開始具有放射性

A precisely similar calculation by Hawking and Gary Gibbons

霍金跟加利 吉布森有一個很類似的計算

showed that if you have dark energy in empty space,

這個計算顯示 如果你在一個空的空間裡有暗能量

then the whole universe radiates.

那麼整個宇宙都是會有放射性的

The energy of empty space

空的空間裡的能量

brings to life quantum fluctuations.

帶來量子波動

And so even though the universe will last forever,

並且即使宇宙永遠存在

and ordinary matter and radiation will dilute away,

普通物質跟放射性被稀釋

there will always be some radiation,

宇宙中總是會有一些放射性存在的

some thermal fluctuations,

還有熱波動

even in empty space.

即使是在這樣一個空的空間裡

So what this means

這就說明

is that the universe is like a box of gas

宇宙就像一個永遠存在的

that lasts forever.

装满的气体的盒子

Well what is the implication of that?

那麼這說明了什麼呢

That implication was studied by Boltzmann back in the 19th century.

博茨曼在19世紀就對此進行了研究

He said, well, entropy increases

他說 熵值增加

because there are many, many more ways

因為相比起低熵值的狀態

for the universe to be high entropy, rather than low entropy.

宇宙有更多方式達到一個高熵值的狀態

But that's a probabilistic statement.

但這是一個概率問題

It will probably increase,

熵值很有可能升高

and the probability is enormously huge.

並且這個可能性是非常巨大的

It's not something you have to worry about --

但是你不用擔心說

the air in this room all gathering over one part of the room and suffocating us.

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

It's very, very unlikely.

這是非常非常不可能的

Except if they locked the doors

除非門被鎖上

and kept us here literally forever,

我們真的永遠的在這里呆下去

that would happen.

剛才所說的情況才能有可能發生

Everything that is allowed,

所有可能發生的情形

every configuration that is allowed to be obtained by the molecules in this room,

所有這個屋子裡的原子所可能形成的所有的組合

would eventually be obtained.

最後總會被實現

So Boltzmann says, look, you could start with a universe

所以博茨曼說 你看 宇宙可以從一個

that was in thermal equilibrium.

熱平衡的狀態開始發展

He didn't know about the Big Bang. He didn't know about the expansion of the universe.

他不知道宇宙大爆炸理論 更不知道宇宙擴張理論

He thought that space and time were explained by Isaac Newton --

他以為牛頓對於時間空間的解釋是正確的 那就是

they were absolute; they just stuck there forever.

時間空間是絕對的 永遠不變的

So his idea of a natural universe

所以博茨曼的自然宇宙的理論

was one in which the air molecules were just spread out evenly everywhere --

認為空氣分子就是平均分散在各處的

the everything molecules.

構成各種東西的分子

But if you're Boltzmann, you know that if you wait long enough,

但是如果你是博茨曼 你會想 如果你足夠耐心

the random fluctuations of those molecules

隨意的分子波動

will occasionally bring them

會時不時的把分子

into lower entropy configurations.

帶入一個較低熵值的構造

And then, of course, in the natural course of things,

當然 之後 按照事物的自然發展規律

they will expand back.

分子會重新回到之前的狀態

So it's not that entropy must always increase --

所以並不是說熵值必須不斷地增加——

you can get fluctuations into lower entropy,

有可能波動使熵值降低

more organized situations.

帶來一個更加齊整的情況

Well if that's true,

那麼 這個說法是正確的話

Boltzmann then goes onto invent

博茨曼進而將會提出

two very modern-sounding ideas --

兩個聽起來非常領先的看法

the multiverse and the anthropic principle.

多層宇宙和人擇原理

He says, the problem with thermal equilibrium

他說 熱平衡狀態的問題是

is that we can't live there.

我們無法生活在這個一個平衡的狀態裡

Remember, life itself depends on the arrow of time.

你應該還記得 生命本身是依賴於時間軸的存在而存在的

We would not be able to process information,

如果在熱平衡的狀態下

metabolize, walk and talk,

我們將無法處理信息 新陳代謝

if we lived in thermal equilibrium.

走路 說話

So if you imagine a very, very big universe,

所以你可能想像一個非常非常大的宇宙

an infinitely big universe,

一個無限大的宇宙

with randomly bumping into each other particles,

裡面的粒子隨機的互相碰撞

there will occasionally be small fluctuations in the lower entropy states,

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

and then they relax back.

然後這些波動會回到原來的狀態

But there will also be large fluctuations.

但同時也會有大規模的波動

Occasionally, you will make a planet

時不時的 這些波動會造出一個行星來

or a star or a galaxy

或者一個恆星 或者一個星系

or a hundred billion galaxies.

或者一千億個星系

So Boltzmann says,

所以博茨曼說

we will only live in the part of the multiverse,

我們只是生活在這個多重宇宙的一個部分裡

in the part of this infinitely big set of fluctuating particles,

一個無限大的不斷波動的粒子堆裡的一部分

where life is possible.

這部分粒子恰巧有可以有生命存在的條件

That's the region where entropy is low.

這個區域也就是有低熵值的一個區域

Maybe our universe is just one of those things

可能我們的宇宙 就是偶爾在這個多重宇宙中出現的

that happens from time to time.

這麼一個低熵值的宇宙

Now your homework assignment

所以 現在我們來佈置家庭作業

is to really think about this, to contemplate what it means.

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

Carl Sagan once famously said

卡爾·薩根曾經提出過一個很有名的說法

that "in order to make an apple pie,

那就是 “你要想做一個蘋果派

you must first invent the universe."

你必須首先做一個宇宙”

But he was not right.

但是他說的不對

In Boltzmann's scenario, if you want to make an apple pie,

在博茨曼的假設情況下 如果你想要做一個蘋果派

you just wait for the random motion of atoms

你只需要耐心等這些隨機的原子

to make you an apple pie.

運動來給你做一個蘋果派

That will happen much more frequently

這個要比這些隨即無序的粒子運動

than the random motions of atoms

現在給你造出一個蘋果園

making you an apple orchard

再給你造出一些糖跟一個火爐

and some sugar and an oven,

然後用這些東西給你做一個蘋果派

and then making you an apple pie.

更容易發生

So this scenario makes predictions.

所以這個假設情況下 我們可以做出一些推測

And the predictions are

包括

that the fluctuations that make us are minimal.

這些造就了我們的波動是很小的

Even if you imagine that this room we are in now

即使你可以想像 這個我們現在所在的屋子

exists and is real and here we are,

事實上存在著 真實存在著 並且我們也存在著

and we have, not only our memories,

我們不僅有記憶 還有一個感知

but our impression that outside there's something

可以知道在我們的存在之外

called Caltech and the United States and the Milky Way Galaxy,

還存在著加州理工 美國 銀河系

it's much easier for all those impressions to randomly fluctuate into your brain

比起這些東西真正的隨機波動

than for them actually to randomly fluctuate

組成加州理工 美國 跟銀河系

into Caltech, the United States and the galaxy.

更有可能發生的是你腦子裡的這些印象感知隨意波動

The good news is that,

好消息是

therefore, this scenario does not work; it is not right.

這個假設情況行不通 是不對的

This scenario predicts that we should be a minimal fluctuation.

這個假設情況推測說 我們應該是微微的波動的

Even if you left our galaxy out,

即使你不考慮我們的星系

you would not get a hundred billion other galaxies.

你也不會得到一千億個其他的星系

And Feynman also understood this.

費曼也這樣認為

Feynman says, "From the hypothesis that the world is a fluctuation,

費曼說 “假設世界是波動著的

all the predictions are that

並且我們的推測都是基於這個想法

if we look at a part of the world we've never seen before,

那麼如果我們去觀察一個新的區域

we will find it mixed up, and not like the piece we've just looked at --

我們將會發現它是混雜的 不像我們剛剛看到的

high entropy.

因為熵值變高了

If our order were due to a fluctuation,

如果我們存在秩序基於這個波動

we would not expect order anywhere but where we have just noticed it.

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

We therefore conclude the universe is not a fluctuation."

這樣 我們就會認為宇宙並不是一個波動的存在

So that's good. The question is then what is the right answer?

好的 那麼個問題的答案到底是什麼

If the universe is not a fluctuation,

如果宇宙不是一個波動的存在

why did the early universe have a low entropy?

為什麼早期宇宙有這樣低的一個熵值

And I would love to tell you the answer, but I'm running out of time.

我很樂意告訴你們這個問題的答案 但是我時間不夠了

(Laughter)

（笑聲）

Here is the universe that we tell you about,

這樣我們就有一個我們給你描述的宇宙 還有

versus the universe that really exists.

一個真實存在的宇宙

I just showed you this picture.

我剛剛向你描述了這個圖像

The universe is expanding for the last 10 billion years or so.

宇宙已經在過去的一百億年中不斷的擴張

It's cooling off.

宇宙現在在冷卻下來

But we now know enough about the future of the universe

但是我們現在對於宇宙的未來知道的足夠多

to say a lot more.

來進行更多的陳述

If the dark energy remains around,

如果暗能量還是存在

the stars around us will use up their nuclear fuel, they will stop burning.

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

They will fall into black holes.

這個恆星那是將會變成黑洞

We will live in a universe

我們將會生活在一個·除了黑洞

with nothing in it but black holes.

什麼都沒有的宇宙裡

That universe will last 10 to the 100 years --

宇宙將會持續存在於這樣的狀態裡大概10的100次方年

a lot longer than our little universe has lived.

比我們的小宇宙存在的時間長很多

The future is much longer than the past.

未來 比過去 要長很多

But even black holes don't last forever.

但是即使是黑洞也不會永遠存在

They will evaporate,

他們會蒸發掉

and we will be left with nothing but empty space.

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

That empty space lasts essentially forever.

空的空間可以說是永遠存在的

However, you notice, since empty space gives off radiation,

但是 你注意到 即使是空的空間 也是有放射性的

there's actually thermal fluctuations,

事實上還是有熱波動的

and it cycles around

然後如此循環

all the different possible combinations

各種不同的在空的空間中存在的

of the degrees of freedom that exist in empty space.

不同程度的”空無一物“的組合

So even though the universe lasts forever,

所以即使宇宙永遠存在

there's only a finite number of things

只有有限的情況

that can possibly happen in the universe.

會發生在宇宙裡

They all happen over a period of time

這些情況都會發生在

equal to 10 to the 10 to the 120 years.

10的10的120次方年的一個時間段裡

So here's two questions for you.

我有兩個問題

Number one: If the universe lasts for 10 to the 10 to the 120 years,

第一個問題 如果宇宙存在了10的10的120次方年

why are we born

為什麼我們人類出現在

in the first 14 billion years of it,

初始的一百四十億年裡

in the warm, comfortable afterglow of the Big Bang?

在這個溫暖 舒適的宇宙大爆炸的餘輝裡？

Why aren't we in empty space?

為什麼我們不是生活在空無一物的空間裡？

You might say, "Well there's nothing there to be living,"

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”

but that's not right.

但是 不是這樣的

You could be a random fluctuation out of the nothingness.

你可以作為一個隨機的無物的波動的產品

Why aren't you?

你為什麼不是這麼一個東西呢？

More homework assignment for you.

這就是你們另一個家庭作業

So like I said, I don't actually know the answer.

就像我說的 我也不知道答案

I'm going to give you my favorite scenario.

我可以告訴你我最喜歡的假設

Either it's just like that. There is no explanation.

有一個可能的解釋是 沒有任何解釋

This is a brute fact about the universe

關於宇宙的一個很難讓人接受的事實

that you should learn to accept and stop asking questions.

就是你必須學會接受現實 停止問問題

Or maybe the Big Bang

或者也有可能 宇宙大爆炸

is not the beginning of the universe.

並不是宇宙的最初開始

An egg, an unbroken egg, is a low entropy configuration,

一個雞蛋 一個完好無損的雞蛋 是一個低熵值的存在

and yet, when we open our refrigerator,

然而 我們打開冰箱的時候

we do not go, "Hah, how surprising to find

我們不會說 “啊哈 這太令人驚訝了

this low entropy configuration in our refrigerator."

我在冰箱裡發現了這麼一個低熵值的玩意”

That's because an egg is not a closed system;

因為雞蛋不是一個封閉的系統

it comes out of a chicken.

一隻雞下了這個雞蛋

Maybe the universe comes out of a universal chicken.

可能宇宙就是一個漁舟雞下的蛋

Maybe there is something that naturally,

可能有一東西 很自然的

through the growth of the laws of physics,

根據一些物理生長法則

gives rise to universe like ours

造就了我們的宇宙

in low entropy configurations.

成為一個低熵值的存在

If that's true, it would happen more than once;

如果這是真的的話 這樣的情況會發生不止一次

we would be part of a much bigger multiverse.

我們會是一個更大的多重宇宙的一部分

That's my favorite scenario.

這是我最喜歡的假設

So the organizers asked me to end with a bold speculation.

組織者要我以一個大膽的設想來結束我的談話

My bold speculation

我的大膽的設想就是

is that I will be absolutely vindicated by history.

歷史毫無疑問的將會證明我的理論是無比正確的

And 50 years from now,

從現在起 五十年後

all of my current wild ideas will be accepted as truths

我現在的所有瘋狂的理論都會被奉為是真理

by the scientific and external communities.

不僅是在科學界 也包括在社會上

We will all believe that our little universe

我們都會相信我們的小小宇宙

is just a small part of a much larger multiverse.

只是一個更大的多重宇宙的一小部分

And even better, we will understand what happened at the Big Bang

還有更好的 在理論層面上

in terms of a theory

我們將會理解宇宙大爆炸的時候發生了什麼

that we will be able to compare to observations.

我們就可以跟我們的觀察結果做對比

This is a prediction. I might be wrong.

這只是一個推測　我可能猜錯

But we've been thinking as a human race

但是人類已經思考了很多年

about what the universe was like,

為什麼宇宙是現在這樣的

why it came to be in the way it did for many, many years.

為什麼它變成現在這樣樣子

It's exciting to think we may finally know the answer someday.

令人激動的是 我們可能會在某一天終於找到答案

Thank you.

謝謝大家

(Applause)

（掌聲）