the Nobel Prize in physics

兩個天文學家的團隊，

was awarded to two teams of astronomers

因為他們所作出的一個

for a discovery that has been hailed

被稱為天文觀測史上

as one of the most important

最重要的觀察之一，

astronomical observations ever.

而獲得了諾貝爾物理學獎。

And today, after briefly describing what they found,

而今天，在簡短的描述他們的發現之後，

I'm going to tell you about a highly controversial framework

我將告訴你們一個可以解釋他們的發現，

for explaining their discovery,

但卻非常有爭議的理論架構。

namely the possibility

那就是，

that way beyond the Earth,

在超出地球，

the Milky Way and other distant galaxies,

超出銀河系和一切遙遠的星系以上，

we may find that our universe

我們可能會明白我們的宇宙

is not the only universe,

并不是唯一的宇宙，

but is instead

而只是一個極度龐大的宇宙群，

part of a vast complex of universes

我們所謂的多元宇宙，

that we call the multiverse.

其中的一個。

Now the idea of a multiverse is a strange one.

多元宇宙的想法有些奇怪。

I mean, most of us were raised to believe

我們大多數人在成長中都被教予

that the word "universe" means everything.

“宇宙”這個詞代表著所有的一切。

And I say most of us with forethought,

我說“我們大多數”是經過考慮的，

as my four-year-old daughter has heard me speak of these ideas since she was born.

因為我的四歲的女兒從出生便開始聽我說這些想法，

And last year I was holding her

而去年當我抱住她

and I said, "Sophia,

然後我對她說： “索菲亞，

I love you more than anything in the universe."

我愛你超過宇宙中所有的一切。”

And she turned to me and said, "Daddy,

然後她轉過來對我說， “爸爸，

universe or multiverse?"

是宇宙還是多元宇宙？”

(Laughter)

（笑聲）

But barring such an anomalous upbringing,

但在這反常的教育以外，

it is strange to imagine

設想和我們的世界

other realms separate from ours,

分離的領域還是很奇怪，

most with fundamentally different features,

它們或許有著從根本上完全不同的特徵，

that would rightly be called universes of their own.

并各自可以被稱作宇宙。

And yet,

但是，雖然

speculative though the idea surely is,

這個設想只是推測，

I aim to convince you

我的目標是說服你們

that there's reason for taking it seriously,

的確有理由來認真的考慮它，

as it just might be right.

因為它有可能就是真的。

I'm going to tell the story of the multiverse in three parts.

我將把多元宇宙的故事分成三部份。

In part one,

在第一部份，

I'm going to describe those Nobel Prize-winning results

我將描述那獲得諾貝爾獎的研究結果，

and to highlight a profound mystery

以及這些結果揭發的

which those results revealed.

一個意義深遠的謎團。

In part two,

在第二部份，

I'll offer a solution to that mystery.

我將為那個謎團提出一個解釋。

It's based on an approach called string theory,

它基於一個叫做弦理論的方法，

and that's where the idea of the multiverse

並會將多元宇宙的概念

will come into the story.

來引進這個故事中。

Finally, in part three,

最終，在第三部份，

I'm going to describe a cosmological theory

我將描述一個叫做“暴脹”的

called inflation,

宇宙論，

which will pull all the pieces of the story together.

而它將把故事所有的片段聯繫在一起。

Okay, part one starts back in 1929

好的。 第一部份從1929年開始。

when the great astronomer Edwin Hubble

著名的天文學家愛德文.哈伯

realized that the distant galaxies

發現遠處的星系

were all rushing away from us,

都在迅速的離我們遠去，

establishing that space itself is stretching,

說明了空間本身正在伸展，

it's expanding.

在擴張。

Now this was revolutionary.

而這是突破性的。

The prevailing wisdom was that on the largest of scales

當時普遍的認知是，在最大的範圍內，

the universe was static.

宇宙是靜止的。

But even so,

但即使如此，

there was one thing that everyone was certain of:

有一件事情是所有人都確信的：

The expansion must be slowing down.

擴張必定在逐漸緩慢下來。

That, much as the gravitational pull of the Earth

就像地球上的萬有引力

slows the ascent of an apple tossed upward,

將往上拋的蘋果的速度慢下來，

the gravitational pull

每一個星系對對方的

of each galaxy on every other

萬有引力

must be slowing

必定也在將空間的擴張

the expansion of space.

緩慢下來。

Now let's fast-forward to the 1990s

現在讓我們快轉到90年代，

when those two teams of astronomers

當我在一開始講到的

I mentioned at the outset

那兩個天文學家的團隊

were inspired by this reasoning

受到了這個推理的啟迪，

to measure the rate

來測量宇宙擴張

at which the expansion has been slowing.

減慢的速度。

And they did this

他們

by painstaking observations

對很多個遠處星系

of numerous distant galaxies,

做出的縝密的觀察

allowing them to chart

允許他們記錄下來

how the expansion rate has changed over time.

宇宙隨著時間過去，擴張速度的變化

Here's the surprise:

而令人吃驚的事情發生了：

They found that the expansion is not slowing down.

他們發現擴張并沒有緩緩減速。

Instead they found that it's speeding up,

相反，他們發現它正在加速，

going faster and faster.

越來越快。

That's like tossing an apple upward

這就像將一個蘋果拋上空中，

and it goes up faster and faster.

然後它往上的速度越來越快。

Now if you saw an apple do that,

如果你看到一個蘋果那樣表現的話，

you'd want to know why.

你會想知道這是爲什麽。

What's pushing on it?

是什麽東西在推動著它？

Similarly, the astronomers' results

同樣的，這些天文學家的結果

are surely well-deserving of the Nobel Prize,

肯定應該獲得諾貝爾獎，

but they raised an analogous question.

但它們也提起了一個相似的問題。

What force is driving all galaxies

是什麽力量在將

to rush away from every other

所有的星系往外

at an ever-quickening speed?

以越來越快的速度推動？

Well the most promising answer

最好的答案

comes from an old idea of Einstein's.

源於愛因斯坦的一個老想法。

You see, we are all used to gravity

你看，我們都習慣於萬有引力

being a force that does one thing,

只做一件事情，

pulls objects together.

那就是將事物拉到一起。

But in Einstein's theory of gravity,

但在愛因斯坦的萬有引力理論，

his general theory of relativity,

它的廣義相對論中，

gravity can also push things apart.

萬有引力也可以將事物推開。

How? Well according to Einstein's math,

這是如何做到的？根據愛因斯坦的計算，

if space is uniformly filled

如果空間被一種

with an invisible energy,

無形的能量均勻的佔據，

sort of like a uniform, invisible mist,

就像一個均勻的，無形的迷霧，

then the gravity generated by that mist

那麼這個迷霧產生的引力

would be repulsive,

將會是相斥的，

repulsive gravity,

而相斥的引力

which is just what we need to explain the observations.

恰恰可以提我們解釋這些觀察結果。

Because the repulsive gravity

因為空間中一種無形的能量

of an invisible energy in space --

產生的相斥的引力 -

we now call it dark energy,

我們現在叫它暗能量，

but I've made it smokey white here so you can see it --

但我在這裡將它變成煙霧般的白色讓你能看到 -

its repulsive gravity

它的相斥的引力

would cause each galaxy to push against every other,

會導致每一個星系互相推動，

driving expansion to speed up,

將擴張速度變快，

not slow down.

而不是變慢。

And this explanation

而這個解釋

represents great progress.

代表著很大的進展。

But I promised you a mystery

但我答應了你在第一部份

here in part one.

有一個謎團。

Here it is.

謎題是如此的:

When the astronomers worked out

當這些天文學家計算出

how much of this dark energy

空間中需要

must be infusing space

多少暗能量

to account for the cosmic speed up,

才能導致現在的宇宙擴張加速，

look at what they found.

看看他們所發現的。

This number is small.

這個數字很小。

Expressed in the relevant unit,

以相應的單位时表示，

it is spectacularly small.

它令人吃驚地小。

And the mystery is to explain this peculiar number.

而謎團便是如何解釋這個古怪的數字。

We want this number

我們想讓這個數字

to emerge from the laws of physics,

從物理定律中自然的浮現，

but so far no one has found a way to do that.

但目前為止沒有人知道如何做。

Now you might wonder,

現在你可能在想，

should you care?

這是你應該關心的嗎？

Maybe explaining this number

或許解釋這個數字

is just a technical issue,

只是一個技術上的問題，

a technical detail of interest to experts,

一個專家對之有興趣的技術細節，

but of no relevance to anybody else.

但對其他人來說沒有任何意義。

Well it surely is a technical detail,

它的確是一個技術細節，

but some details really matter.

但有些細節真的狠重要。

Some details provide

有些細節可以為

windows into uncharted realms of reality,

探索未知的現實提供一扇窗。

and this peculiar number may be doing just that,

而這個特殊的數字很有可能就是這扇窗，

as the only approach that's so far made headway to explain it

因為到目前為止，唯一一個可以解釋它的方法

invokes the possibility of other universes --

包括了其他宇宙的存在的可能 -

an idea that naturally emerges from string theory,

一個從弦理論中自然而然浮現的理念，

which takes me to part two: string theory.

而從這裡我開始講第二部份： 弦理論。

So hold the mystery of the dark energy

請將神秘的暗能量

in the back of your mind

暫時放在腦後，

as I now go on to tell you

因為我將告訴你

three key things about string theory.

關於弦理論的三個關鍵的事情。

First off, what is it?

首先，弦理論是什麽？

Well it's an approach to realize Einstein's dream

它是一個可以完成愛因斯坦的夢想，

of a unified theory of physics,

一個統一的物理理論的方法，

a single overarching framework

一個可以形容

that would be able to describe

宇宙中所有運行的力的

all the forces at work in the universe.

全面的思想架構。

And the central idea of string theory

而弦理論的中心思想

is quite straightforward.

很直接明瞭。

It says that if you examine

它說，如果你近乎無限仔細的考察

any piece of matter ever more finely,

任何一個物質，

at first you'll find molecules

一開始你會發現分子，

and then you'll find atoms and subatomic particles.

然後你會發現原子和次原子微粒。

But the theory says that if you could probe smaller,

但弦理論說，如果你能夠在探查的更細微一些，

much smaller than we can with existing technology,

比任何我們現在擁有的科技可以做到的都細微，

you'd find something else inside these particles --

你會發現在這些微粒中還有東西 --

a little tiny vibrating filament of energy,

一個很小的，振動的能量絲，

a little tiny vibrating string.

一個很小的，振動的弦。

And just like the strings on a violin,

而就像一個小提琴的琴弦一樣，

they can vibrate in different patterns

它們可以以不同的頻率振動，

producing different musical notes.

產生不同的音調。

These little fundamental strings,

這些小的基礎的弦們，

when they vibrate in different patterns,

當它們以不同的頻率振動的時候，

they produce different kinds of particles --

它們會產生不同的微粒，

so electrons, quarks, neutrinos, photons,

比如電子，夸克，中微子，光子，

all other particles

以及所有的其他的微粒

would be united into a single framework,

都會被統一在一個體系之下，

as they would all arise from vibrating strings.

因為他們都由振動的弦構成。

It's a compelling picture,

這是一個非常扣人心弦的構想，

a kind of cosmic symphony,

一種星雲交響曲，

where all the richness

我們所看到周圍的

that we see in the world around us

這個世界上的富饒的一切，

emerges from the music

都在這些細小的弦的

that these little, tiny strings can play.

演奏中形成。

But there's a cost

但這個優美的統一理論

to this elegant unification,

有著一個代價，

because years of research

因為多年的研究

have shown that the math of string theory doesn't quite work.

表明了弦理論的數學不怎麼貫通。

It has internal inconsistencies,

它有著內在的矛盾，

unless we allow

除非我們考慮

for something wholly unfamiliar --

一個我們完全不熟悉的東西 --

extra dimensions of space.

額外的空間維度。

That is, we all know about the usual three dimensions of space.

我們每個人都知道常見的三個空間維度。

And you can think about those

而你也可以將它們想成

as height, width and depth.

高度，寬度，和長度。

But string theory says that, on fantastically small scales,

但弦理論說，在極度小的比例上，

there are additional dimensions

存在著額外的維度，

crumpled to a tiny size so small

縮小到了我們還無法

that we have not detected them.

測試到的地步。

But even though the dimensions are hidden,

但雖然那些維度被隱藏著，

they would have an impact on things that we can observe

它們對於我們可以觀察的東西有著一定的影響，

because the shape of the extra dimensions

因為這些額外的維度的形狀

constrains how the strings can vibrate.

決定了弦們如何振動。

And in string theory,

而在弦理論中，

vibration determines everything.

振動決定一切。

So particle masses, the strengths of forces,

所以微粒質量，力的力度，

and most importantly, the amount of dark energy

以及最重要的，暗能量的數量

would be determined

都會由這些額外的維度的

by the shape of the extra dimensions.

形狀決定。

So if we knew the shape of the extra dimensions,

而如果我們知道了這些額外維度的形狀，

we should be able to calculate these features,

我們應該可以計算這些特徵，

calculate the amount of dark energy.

計算暗能量的數量。

The challenge

我們的挑戰是，

is we don't know

我們并不知道

the shape of the extra dimensions.

這些額外維度的形狀。

All we have

我們只知道

is a list of candidate shapes

一些數學允許的

allowed by the math.

候選形狀。

Now when these ideas were first developed,

當這些想法第一次被發展出來的時候，

there were only about five different candidate shapes,

候選的形狀只有五個左右，

so you can imagine

所以你會覺得

analyzing them one-by-one

將它們一個一個的分析

to determine if any yield

來決定是否有一個可以產生

the physical features we observe.

我們觀察到的物理特徵。

But over time the list grew

但隨著研究人員不斷的找到其他的候選形狀

as researchers found other candidate shapes.

數量不斷的在增加。

From five, the number grew into the hundreds and then the thousands --

它的數字從五個增長到幾百個甚至幾千個 --

A large, but still manageable, collection to analyze,

一個雖然龐大，但仍然可以處理和分析的數字，

since after all,

因為不管如何，

graduate students need something to do.

研究博士生們總需要些事情做。

But then the list continued to grow

但這個清單繼續增長

into the millions and the billions, until today.

到了百萬甚至今天的數十億。直到今天，

The list of candidate shapes

候選形狀的清單

has soared to about 10 to the 500.

百億從猛增到了萬億。

So, what to do?

現在該怎麼辦？

Well some researchers lost heart,

有一些研究人員失去了信心，

concluding that was so many candidate shapes for the extra dimensions,

覺得因為額外維度有著如此之多的候選形狀，

each giving rise to different physical features,

每一個又可能產生不同的物理特徵，

string theory would never make

弦理論永遠也不可能做出

definitive, testable predictions.

確定的，可測試的預測。

But others turned this issue on its head,

但其他人決定從問題的源頭開始，

taking us to the possibility of a multiverse.

回到一個多元宇宙的可能。

Here's the idea.

想法是這樣的。

Maybe each of these shapes is on an equal footing with every other.

或許這些形狀的每一個都是與其他的形狀平等的。

Each is as real as every other,

每一個都是真實的，

in the sense

這意味著

that there are many universes,

有著很多的宇宙，

each with a different shape, for the extra dimensions.

每一個都有著不同形狀的額外維度。

And this radical proposal

這一個重大的提論

has a profound impact on this mystery:

對於這個謎題有著深遠的影響：

the amount of dark energy revealed by the Nobel Prize-winning results.

關於著那得了諾貝爾獎的暗能量的數量。

Because you see,

因為

if there are other universes,

如果有著其他的宇宙，

and if those universes

以及如果那些宇宙每一個的額外維度

each have, say, a different shape for the extra dimensions,

都有一個不同的形狀

then the physical features of each universe will be different,

那麼每一個宇宙的物理特徵就會不同，

and in particular,

而特別的，