Making sense of string theory | Brian Greene

譯者: K. C. Peng 審譯者: Lin Su-Wei(林書暐)

In the year 1919,

在1919年,

a virtually unknown German mathematician, named Theodor Kaluza

一位鮮為人知的德國數學家Theodor Kaluza

suggested a very bold and, in some ways, a very bizarre idea.

提出一非常大膽, 或可稱作非常怪異的想法

He proposed that our universe

他提議說我們的宇宙

might actually have more than the three dimensions

可能不僅僅是只有三度空間

that we are all aware of.

在所熟知的

That is in addition to left, right, back, forth and up, down,

左右, 前後, 上下以外, 還可以有其他維度

Kaluza proposed that there might be additional dimensions of space

Kaluza建議的額外維度空間

that for some reason we don't yet see.

只是因為某些原因, 造成我們並不察覺

Now, when someone makes a bold and bizarre idea,

嘿! 當有人提出大膽與怪異的想法

sometimes that's all it is -- bold and bizarre,

常常就只是大膽與怪異而已

but it has nothing to do with the world around us.

又常與真實世界沒有關聯

This particular idea, however --

但是, 就這個特殊的想法

although we don't yet know whether it's right or wrong,

雖然我們尚未知道其真偽

and at the end I'll discuss experiments which, in the next few years,

待會兒, 我會描述未來幾年內的一個實驗

may tell us whether it's right or wrong --

就或許能為我們解答其對或錯

this idea has had a major impact on physics in the last century

此想法對上世紀的物理學有著重大的衝擊

and continues to inform a lot of cutting-edge research.

也持續引領著許多的前瞻研究

So, I'd like to tell you something about the story of these extra dimensions.

因此, 我想要告訴各位有關額外維度的故事

So where do we go?

那麼怎麼開始呢?

To begin we need a little bit of back story. Go to 1907.

我們需要了解些背景故事, 回到1907年吧

This is a year when Einstein is basking in the glow

那個年代正是Einstein榮耀地發現了

of having discovered the special theory of relativity

"特殊(狹義)相對論"

and decides to take on a new project,

而決定開始新的挑戰 --

to try to understand fully the grand, pervasive force of gravity.

試著對崇高又普遍的重力作充分了解

And in that moment, there are many people around

但當時, 有許多人以為重力的問題

who thought that that project had already been resolved.

早就已經被解決了

Newton had given the world a theory of gravity in the late 1600s

Newton於1600末, 就已經提出地心引力的理論

that works well, describes the motion of planets,

大到行星的運動

the motion of the moon and so forth,

月亮的運行等等

the motion of apocryphal of apples falling from trees,

小到連理論的開場: 樹上蘋果落下

hitting people on the head.

擊中人們的頭頂

All of that could be described using Newton's work.

都能被Newton的理論妥善解釋

But Einstein realized that Newton had left something out of the story,

但Einstein明白Newton的理論似乎缺少什麼

because even Newton had written

因為, 就連Newton自己也曾這麼寫著

that although he understood how to calculate the effect of gravity,

雖然明白如何計算地心引力

he'd been unable to figure out how it really works.

但還是未能了解全貌:

How is it that the Sun, 93 million miles away,

太陽遠在9千3百萬英哩之外

[that] somehow it affects the motion of the Earth?

卻能影響地球的運動?

How does the Sun reach out across empty inert space and exert influence?

到底太陽是如何經過真空狀態的空間還能產生影響?

And that is a task to which Einstein set himself --

這就是Einstein給自己的難題

to figure out how gravity works.

解開重力作用的原理

And let me show you what it is that he found.

容我告訴你們他的發現

So Einstein found

Einstein發現了:

that the medium that transmits gravity is space itself.

傳遞重力場的介質就是空間本身

The idea goes like this:

概念如下:

imagine space is a substrate of all there is.

想像空間就是所有物質的一基本載具

Einstein said space is nice and flat, if there's no matter present.

當無其他物質存在時, Einstein認為空間是平坦的,

But if there is matter in the environment, such as the Sun,

但當有物質, 如太陽, 處於空間時

it causes the fabric of space to warp, to curve.

會造成空間直線網格的翹曲與扭曲

And that communicates the force of gravity.

太陽也就是利用空間本身傳遞了重力

Even the Earth warps space around it.

即使是地球也使其週遭的空間扭曲

Now look at the Moon.

來看月球吧!

The Moon is kept in orbit, according to these ideas,

月球就是依據這樣解釋, 而能於固定軌道上運行

because it rolls along a valley in the curved environment

因為它繞著一扭曲的凹陷轉圈

that the Sun and the Moon and the Earth can all create by virtue of their presence.

太陽, 月球, 地球都因各有質量存在, 而能造成空間扭曲

We go to a full-frame view of this.

從一全景的角度來明瞭

The Earth itself is kept in orbit

地球自己是保持在一固定軌道

because it rolls along a valley in the environment that's curved

因為它繞著一扭曲的凹陷轉圈

because of the Sun's presence.

這主要是因為太陽存在所引起的

That is this new idea about how gravity actually works.

對重力的作用, 這是一全新的解釋

Now, this idea was tested in 1919 through astronomical observations.

這理論也於1919年的天文觀測得到最佳驗證

It really works. It describes the data.

理論成功解釋了觀測的數據

And this gained Einstein prominence around the world.

也為Einstein爭取到享譽全球的地位

And that is what got Kaluza thinking.

這理論的成功也讓Kaluza再深思

He, like Einstein, was in search of what we call a unified theory.

他和Einstein都在找一所謂的"統一理論"

That's one theory

那是個單一理論

that might be able to describe all of nature's forces from one set of ideas,

用來描述所有的作用力, 只用一組的概念

one set of principles, one master equation, if you will.

只用一組的原理, 只用一組的主要方程式

So Kaluza said to himself,

因此, Kaluza告訴自己:

Einstein has been able to describe gravity

"Einstein已能用空間的扭曲

in terms of warps and curves in space --

來描述重力" --

in fact, space and time, to be more precise.

更精確的說 是時間與空間都被扭曲

Maybe I can play the same game with the other known force,

"或許我也能對其他的作用力玩同樣的模式"

which was, at that time, known as the electromagnetic force --

也就是當時知道的電磁力

we know of others today, but at that time

現今的我們知道有更多種作用力, 但當時

that was the only other one people were thinking about.

除重力以外, 只知一種作用力

You know, the force responsible for electricity

那就是 解釋電流磁場

and magnetic attraction and so forth.

吸引互斥的電磁力

So Kaluza says, maybe I can play the same game

因此Kaluza 才會說: "或許我也能

and describe electromagnetic force in terms of warps and curves.

描述電磁力是一種的扭曲"

That raised a question: warps and curves in what?

緊接著的問題是: 什麼東西被扭曲了?

Einstein had already used up space and time,

Einstein已經用去了3維空間與時間

warps and curves, to describe gravity.

的扭曲來解釋重力

There didn't seem to be anything else to warp or curve.

似乎沒有其他的維度可被扭曲

So Kaluza said, well, maybe there are more dimensions of space.

所以Kaluza說: "哦, 或許空間有更多的維度"

He said, if I want to describe one more force,

他說: "如果我需要一統地再描述一個作用力

maybe I need one more dimension.

我就只需再一個維度"

So he imagined that the world had four dimensions of space, not three,

所以他想像宇宙需要4維度的空間, 不是只有3維

and imagined that electromagnetism was warps and curves

同時想像電磁作用力是被扭曲

in that fourth dimension. Now here's the thing:

在那第4度空間, 接著

when he wrote down the equations describing warps and curves

當他具體以數學式子來描述扭曲

in a universe with four space dimensions, not three,

的4度空間, 留意不是慣有的3度空間

he found the old equations that Einstein had already derived in three dimensions --

他發現能推導出不只是 Einstein為了說明重力

those were for gravity --

已導出的3度空間數學式

but he found one more equation because of the one more dimension.

但同時因多出的一維度也多導出另一數學式

And when he looked at that equation,

再仔細的推敲此一數學式

it was none other than the equation

它不是別的

that scientists had long known to describe the electromagnetic force.

就是科學家一直以來用來描述電磁力的數學式

Amazing -- it just popped out.

令人驚奇 --- 它就這樣一統地出現

He was so excited by this realization

他是如此的興奮, 就因純數學理論的推導

that he ran around his house screaming, "Victory!" --

他狂喜地在屋內奔跳, 喊著"勝利!"

that he had found the unified theory.

因他已找到一統作用力的理論

Now clearly, Kaluza was a man who took theory very seriously.

明顯地, Kaluza是堅信理論推導的人

He, in fact --

事實上, 他

there is a story that when he wanted to learn how to swim,

也有著這樣的小故事: 當他想學游泳時

he read a book, a treatise on swimming --

他選擇讀書, 一本游泳的專著

(Laughter)

(觀眾笑聲)

-- then dove into the ocean.

-- 然後躍入海中

This is a man who would risk his life on theory.

他是一個願意堅信理論而冒生命危險的人

Now, but for those of us who are a little bit more practically minded,

但是對我們這些較有務實想法的人

two questions immediately arise from his observation.

兩個疑問隨即挑戰他的觀察

Number one: if there are more dimensions in space, where are they?

第一: 若有額外的空間維度, 那是在哪?

We don't seem to see them.

我們並沒能看到其他維度

And number two: does this theory really work in detail,

第二: 如此的理論, 真的能仔細適用

when you try to apply it to the world around us?

到眾所週知的世界嗎?

Now, the first question was answered in 1926

第一個疑點於1926年被解釋

by a fellow named Oskar Klein.

是由一名叫 Oskar Klein 所為

He suggested that dimensions might come in two varieties --

他提出空間的維度可以兩種型式存在

there might be big, easy-to-see dimensions,

一種是大尺度, 能輕易用肉眼察覺的維度

but there might also be tiny, curled-up dimensions,

但也可以存在一種微小翹起的維度

curled up so small, even though they're all around us,

翹起的如此渺小, 即使是充滿在我們的四週

that we don't see them.

我們還是難以看見

Let me show you that one visually.

讓我以影像動畫說明

So, imagine you're looking at something

想像你們看著某件事

like a cable supporting a traffic light.

像是拉著交通號誌的鋼索

It's in Manhattan. You're in Central Park -- it's kind of irrelevant --

是在曼哈頓的中央公園拍的, 但這不是相關的

but the cable looks one-dimensional from a distant viewpoint,

這鋼索從一遠方看是一維度的

but you and I all know that it does have some thickness.

但你我都明白, 這鋼索有著些厚度

It's very hard to see it, though, from far away.

但從一遠遠的距離, 它是非常難被想像的

But if we zoom in and take the perspective of, say,

但當我們拉近觀察, 從不同的觀點, 舉例說

a little ant walking around --

是小小螞蟻的角度看

little ants are so small that they can access all of the dimensions --

螞蟻是如此的微小, 它們能通行所有的維度

the long dimension,

這綿長的直線維度

but also this clockwise, counter-clockwise direction.

以及順時逆時的旋轉維度

And I hope you appreciate this.

希望你們會讚嘆這拍攝

It took so long to get these ants to do this.

這需要很長的等待才拍到螞蟻如此行動

(Laughter)

(笑聲)

But this illustrates the fact that dimensions can be of two sorts:

主要是以視覺說明維度可以有兩種

big and small. And the idea that maybe the big dimensions around us

大維度與小維度, 大維度就是我們周遭

are the ones that we can easily see,

都能輕易見到的

but there might be additional dimensions curled up,

但同時也有額外翹起的小維度

sort of like the circular part of that cable,

就像是鋼索的旋轉部分

so small that they have so far remained invisible.

是如此的小, 以致不可見

Let me show you what that would look like.

讓我以圖形幫助大家理解

So, if we take a look, say, at space itself --

當我們看著空間本身

I can only show, of course, two dimensions on a screen.

現在只能用兩度空間的形式展現於螢幕上

Some of you guys will fix that one day,

或許有天你們能改善這種展示

but anything that's not flat on a screen is a new dimension,

超越螢幕的平坦想像, 就是一個新的維度

goes smaller, smaller, smaller,

一直放大, 放大, 放大,

and way down in the microscopic depths of space itself,

一直到微觀的空間本身深度

this is the idea,

形容如下

you could have additional curled up dimensions --

你可以有額外翹起的維度

here is a little shape of a circle -- so small that we don't see them.

就如微小的圓圈 --- 如此的小所以不可見

But if you were a little ultra microscopic ant walking around,

但想像你是超細小的螞蟻走在維度中

you could walk in the big dimensions that we all know about --

你可以走在習以為常的大維度

that's like the grid part --

就是格網之上

but you could also access the tiny curled-up dimension

你也可以進入微小翹起的維度

that's so small that we can't see it with the naked eye

那是如此的細小, 以致肉眼無法辨識

or even with any of our most refined equipment.

即使是我們就精密的設備, 也無法辨識

But deeply tucked into the fabric of space itself,

仍然隱藏在空間本身的編織中

the idea is there could be more dimensions, as we see there.

要說明的概念就是空間能有額外的維度

Now that's an explanation

這也就大致解釋了

about how the universe could have more dimensions than the ones that we see.

宇宙可以有比我們所見的更多的維度

But what about the second question that I asked:

那至於我提的第二個疑點呢?

does the theory actually work

當我們將它應用到現實世界

when you try to apply it to the real world?

這樣的理論真的可行嗎?

Well, it turns out that Einstein and Kaluza and many others

結果是, Einstein, Kaluza與其他學者

worked on trying to refine this framework

試著微調理論架構的細項

and apply it to the physics of the universe

再應用到當時所理解的宇宙物理

as was understood at the time, and, in detail, it didn't work.

但實際觀察比對, 卻不能全面符合

In detail, for instance,

詳細舉例來說

they couldn't get the mass of the electron

他們無法單由此理論的推導

to work out correctly in this theory.

正確計算出電子的質量

So many people worked on it, but by the '40s, certainly by the '50s,

非常多人的努力, 直到1940年代, 甚至1950年代

this strange but very compelling idea

這個奇異但吸引的想法 ---

of how to unify the laws of physics had gone away.

一統物理的定律 --- 已經逐漸被放棄

Until something wonderful happened in our age.

直到我們的年代出現了奇想

In our era, a new approach to unify the laws of physics

一種新的一統物理定律的理論

is being pursued by physicists such as myself,

持續由像我一樣的許多物理學家

many others around the world,

分散各地努力提出解釋

it's called superstring theory, as you were indicating.

就是你們被提示的, 叫做"超弦理論"

And the wonderful thing is that superstring theory

超弦理論奇妙的地方是

has nothing to do at first sight with this idea of extra dimensions,

第一眼看到時, 是與額外的維度無關

but when we study superstring theory,

但當我們深入讀其理論

we find that it resurrects the idea in a sparkling, new form.

就會發現該想法又復活了, 而且是以一個亮麗的新形式出現

So, let me just tell you how that goes.

容許我直接做個介紹

Superstring theory -- what is it?

什麼是"超弦理論"?

Well, it's a theory that tries to answer the question:

嗯, 這裡論試著回答這個問題:

what are the basic, fundamental, indivisible, uncuttable constituents

什麼是物質最基本, 不能再分裂, 與再分割的成分

making up everything in the world around us?

在我們的周遭世界呢?

The idea is like this.

這理論大致像這樣

So, imagine we look at a familiar object, just a candle in a holder,

所以簡單舉例些我們熟悉的事物, 如燭台上的蠟燭

and imagine that we want to figure out what it is made of.

想像我們想要明白它的組成

So we go on a journey deep inside the object and examine the constituents.

我們可以展開一深入物體的旅程, 並分析其成分

So deep inside -- we all know, you go sufficiently far down, you have atoms.

深入後 -- 我們都明白可以看到原子的成分

We also all know that atoms are not the end of the story.

當然也知道原子並非最終的成分

They have little electrons that swarm around a central nucleus

會是電子繞著原子核的組成

with neutrons and protons.

而原子核又是由中子與質子構成

Even the neutrons and protons have smaller particles inside of them known as quarks.

就連中子與質子還有更小的成分, 被稱為夸克

That is where conventional ideas stop.

這是過去認為的終點

Here is the new idea of string theory.

弦理論提出了新想法

Deep inside any of these particles, there is something else.

在所有基本粒子內部, 還有其他共同成分

This something else is this dancing filament of energy.

就是一些跳動的能量細絲

It looks like a vibrating string --

就像是震動的弦

that's where the idea, string theory comes from.

這就是弦理論的開始

And just like the vibrating strings that you just saw in a cello

就像是大提琴上的弦

can vibrate in different patterns,

能以多種模式震盪

these can also vibrate in different patterns.

粒子中的弦也有多種模式的震盪

They don't produce different musical notes.

它們並不產生不同的音階

Rather, they produce the different particles making up the world around us.

而是產生多種不同的宇宙基本粒子

So if these ideas are correct,

如果這個想法是對的

this is what the ultra-microscopic landscape of the universe looks like.

這就是超微觀宇宙的狀況

It's built up of a huge number

有著龐大數量的

of these little tiny filaments of vibrating energy,

震盪能量細絲,

vibrating in different frequencies.

以不同的頻率震盪著

The different frequencies produce the different particles.

不同的頻率就對應到不同的基本粒子成分

The different particles are responsible

而不同的基本粒子就負責

for all the richness in the world around us.

組成目前所見的宇宙

And there you see unification,

而這就是一統的概念

because matter particles, electrons and quarks,

因為粒子, 電子, 夸克

radiation particles, photons, gravitons, are all built up from one entity.

輻射粒子, 光子, 引力子, 可以都由單一的弦理論構成

So matter and the forces of nature all are put together

換言之, 自然界的物質與作用力都由

under the rubric of vibrating strings.

震盪的弦依規則而組成

And that's what we mean by a unified theory.

這就是我們認為的"一統理論"

Now here is the catch.

這裡有個困擾

When you study the mathematics of string theory,

當研讀弦理論的數學

you find that it doesn't work

你會發現這是不通 當設定是

in a universe that just has three dimensions of space.

在一個3度空間的宇宙中

It doesn't work in a universe with four dimensions of space, nor five, nor six.

即使是4度, 5度, 6度的空間都不能成功

Finally, you can study the equations, and show that it works

最後, 當數學式合理時, 就會發現 ---

only in a universe that has 10 dimensions of space

只有在空間是10維度時

and one dimension of time.

再加上1維度的時間 才行

It leads us right back to this idea of Kaluza and Klein --

這就帶回到當初Kaluza 與Klein 的概念:

that our world, when appropriately described,

在適當的描述我們的世界時

has more dimensions than the ones that we see.

是需要有較所見還多的維度

Now you might think about that and say, well,

就開始這麼想像

OK, you know, if you have extra dimensions, and they're really tightly curled up,

有額外的維度, 是捲曲的維度

yeah, perhaps we won't see them, if they're small enough.

而它們是如此的微小, 所以肉眼難辨

But if there's a little tiny civilization of green people walking around down there,

再想像那兒有著小綠人的文明世界

and you make them small enough, and we won't see them either. That is true.

他們也是如此的小, 所以我們也就無法見到, 是真的

One of the other predictions of string theory --

這小綠人是弦理論的預測

no, that's not one of the other predictions of string theory.

不, 開玩笑的, 這不是弦理論的預測

(Laughter)

(笑聲)

But it raises the question:

但這樣也產生一個疑問

are we just trying to hide away these extra dimensions,

是我們刻意隱藏這些額外的維度嗎?

or do they tell us something about the world?

或是它們能告訴我們有關這個世界嗎?

In the remaining time, I'd like to tell you two features of them.

接下來的時間, 我會告訴大家弦理論的兩大特點

First is, many of us believe that these extra dimensions

第一, 許多的我們相信, 這些額外維度

hold the answer to what perhaps is the deepest question

能揭露出對理論物理與理論科學

in theoretical physics, theoretical science.

最深層的解釋

And that question is this: when we look around the world,

而那被解釋的疑問就是: 當我們環顧這個世界的常數

as scientists have done for the last hundred years,

這些也是幾百年來科學家的所成就的

there appear to be about 20 numbers that really describe our universe.

用約20個數字就能描述我們的宇宙

These are numbers like the mass of the particles,

例如各基本粒子的質量

like electrons and quarks, the strength of gravity,

像電子與夸克的, 如重力強度

the strength of the electromagnetic force --

如電磁力的強度

a list of about 20 numbers

而且這些約20個的數字

that have been measured with incredible precision,

早已被精確的測量過

but nobody has an explanation

但卻沒人解釋

for why the numbers have the particular values that they do.

為什麼它們是呈現那些數值大小?

Now, does string theory offer an answer?

那弦理論能提供個答案嗎?

Not yet.

還不行

But we believe the answer for why those numbers have the values they do

但我們相信各數值的特定表現

may rely on the form of the extra dimensions.

會根據這些額外的維度模式

And the wonderful thing is, if those numbers

奇妙的事是: 如果這些數字

had any other values than the known ones,

有其他的不同數值表現

the universe, as we know it, wouldn't exist.

那我們的宇宙便不會存在

This is a deep question.

這便有著深層的疑問

Why are those numbers so finely tuned

為何這些數字是如此的被決定

to allow stars to shine and planets to form,

使得星星發光與行星成型

when we recognize that if you fiddle with those numbers --

我們也明瞭當操弄這些數值時 ---

if I had 20 dials up here

就像是有20個的強弱旋扭

and I let you come up and fiddle with those numbers,

你可以隨意調動這些數值

almost any fiddling makes the universe disappear.

幾乎是任何的變動都會使宇宙不存在

So can we explain those 20 numbers?

那我們能解釋這些20個常數嗎?

And string theory suggests that those 20 numbers

弦理論建議這20個數字

have to do with the extra dimensions.

與額外的維度有關

Let me show you how.

容我向你說明

So when we talk about the extra dimensions in string theory,

在弦理論中引用這些額外的空間維度時

it's not one extra dimension,

並不是如Kaluza與Klein

as in the older ideas of Kaluza and Klein.

所形容的維度想法

This is what string theory says about the extra dimensions.

弦理論稱這些額外維度

They have a very rich, intertwined geometry.

是有著錯綜複雜的幾何

This is an example of something known as a Calabi-Yau shape --

這就是Calabi-Yau 形狀的舉例

name isn't all that important.

名字並非那麼重要

But, as you can see,

但可看到的是

the extra dimensions fold in on themselves

這額外的維度會於它們維度之中摺疊

and intertwine in a very interesting shape, interesting structure.

糾纏成有趣的形狀與有趣的結構

And the idea is that if this is what the extra dimensions look like,

關於額外維度的這樣概念是

then the microscopic landscape of our universe all around us

告訴我們這個宇宙

would look like this on the tiniest of scales.

在微小的尺度下, 會是如此呈現

When you swing your hand,

當你揮動手時

you'd be moving around these extra dimensions over and over again,

就是重複地於這些額外的維度運動

but they're so small that we wouldn't know it.

但它們是如此的小, 以致於我們不會察覺

So what is the physical implication, though, relevant to those 20 numbers?

那到底是什麼物理的意涵相關於這些20個數字呢?

Consider this. If you look at the instrument, a French horn,

想像你看著一個樂器, 法國號為例

notice that the vibrations of the airstreams

會注意到氣流的震動

are affected by the shape of the instrument.

是被樂器的形狀所影響

Now in string theory,

在弦理論中

all the numbers are reflections of the way strings can vibrate.

所有的數字呈現的狀態就是弦所能震動的不同模式

So just as those airstreams

就像是樂器中的氣流

are affected by the twists and turns in the instrument,

隨著樂器的轉折扭曲的表現

strings themselves will be affected

弦會於幾何行進間

by the vibrational patterns in the geometry within which they are moving.

受自身震動模式的影響

So let me bring some strings into the story.

讓我將弦引導入這說明中

And if you watch these little fellows vibrating around --

當你看到它們這些小傢伙震動著 ---

they'll be there in a second -- right there,

它們馬上會出現在畫面中 --- 那裡!

notice that they way they vibrate is affected

注意到它們的震動模式會受

by the geometry of the extra dimensions.

幾何上額外的維度所影響

So, if we knew exactly what the extra dimensions look like --

所以如果我們知道額外空間的確實長相

we don't yet, but if we did --

目前尚未明瞭, 但如果我們知道了

we should be able to calculate the allowed notes,

我們便能計算出這些允許的音節

the allowed vibrational patterns.

也就是允許的震動模式

And if we could calculate the allowed vibrational patterns,

如果我們能計算出這些允許的震動模式

we should be able to calculate those 20 numbers.

我們也就能計算出這些20個數值

And if the answer that we get from our calculations

而這些計算結果

agrees with the values of those numbers

又能與早先數據

that have been determined

相吻合的話

through detailed and precise experimentation,

這些數據都是由實驗精準測量的

this in many ways would be the first fundamental explanation

那麼這些理論計算就是第一次能解釋

for why the structure of the universe is the way it is.

為何宇宙是如此的架構與目前的狀態

Now, the second issue that I want to finish up with is:

現在, 第二個我想帶出的議題是:

how might we test for these extra dimensions more directly?

要如何能直接驗證這些額外的維度呢?

Is this just an interesting mathematical structure

還是它們只是存在有趣的數學理論架構中 ---

that might be able to explain

來解釋

some previously unexplained features of the world,

過去世上並未能被解釋的問題嗎?

or can we actually test for these extra dimensions?

或是我們真的能設法測試這些額外的維度嗎?

And we think -- and this is, I think, very exciting --

我們認為或是我認為 這將是非常令人興奮的

that in the next five years or so we may be able to test

約在五年後, 我們便能測試

for the existence of these extra dimensions.

這些額外維度的存在與否

Here's how it goes. In CERN, Geneva, Switzerland,

這是這樣的, 在瑞士 日內瓦的CERN實驗室

a machine is being built called the Large Hadron Collider.

一個名叫"大型重子對撞機"正被建造中

It's a machine that will send particles around a tunnel,

是個於真空管道中 傳送兩束相反方向

opposite directions, near the speed of light.

以近光速運行的粒子束

Every so often those particles will be aimed at each other,

某些時候 兩束粒子能被聚焦在同一點上

so there's a head-on collision.

也就能發生正面對撞

The hope is that if the collision has enough energy,

希望會發生的是: 當對撞有足夠的高能量

it may eject some of the debris from the collision

就可能由對撞中彈射出一些殘屑

from our dimensions, forcing it to enter into the other dimensions.

會從我們所處的維度 強迫它進入其他的維度

How would we know it?

我們又是如何知道這件事?

Well, we'll measure the amount of energy after the collision,

因為我們會測量對撞後的總能量

compare it to the amount of energy before,

與對撞前之總能量相比較

and if there's less energy after the collision than before,

如果對撞後的總能量小於對撞前

this will be evidence that the energy has drifted away.

那這就是能量已飄移的證據

And if it drifts away in the right pattern that we can calculate,

如果這飄移剛好是我們能計算的模式

this will be evidence that the extra dimensions are there.

這也就是額外維度存在的證據

Let me show you that idea visually.

再讓我以視覺呈現的方式說明

So, imagine we have a certain kind of particle called a graviton --

所以假設我們有一種基本粒子叫"引力子"

that's the kind of debris we expect to be ejected out,

這粒子也是我們希望當額外的維度是真的

if the extra dimensions are real.

那從對撞實驗能發現噴射出的新物質

But here's how the experiment will go.

整個實驗就是這麼進行

You take these particles. You slam them together.

用粒子束對撞

You slam them together, and if we are right,

再對撞, 如果我們是對的

some of the energy of that collision

那碰撞後的部分高能量

will go into debris that flies off into these extra dimensions.

會產生新基本粒子, 而飛入額外的維度中

So this is the kind of experiment

所以這樣的實驗

that we'll be looking at in the next five, seven to 10 years or so.

會是我們未來5, 7, 到10年的努力重點

And if this experiment bears fruit,

若實驗有了結果

if we see that kind of particle ejected

我們能見到那種粒子被噴射出

by noticing that there's less energy in our dimensions

也注意在我們的維度中總能量

than when we began,

有比對撞之前短少

this will show that the extra dimensions are real.

這就能證明額外維度是存在的

And to me this is a really remarkable story,

對我而言, 這將會是非常了不起的故事

and a remarkable opportunity. Going back to Newton with absolute space --

將會是非常了不起的機會. 回到Newton理論的絕對空間

didn't provide anything but an arena, a stage

只是提供一個場地與舞台

in which the events of the universe take place.

容許宇宙的所有事件就發生其上

Einstein comes along and says,

Einstein出現並提出

well, space and time can warp and curve -- that's what gravity is.

空間與時間是參與改變的, 被重力所翹曲與捲曲

And now string theory comes along and says,

現在弦理論更進一步提出

yes, gravity, quantum mechanics, electromagnetism,

重力, 量子力學, 電磁學 ---

all together in one package,

都能被一套理論所解釋

but only if the universe has more dimensions than the ones that we see.

但條件是這個宇宙需要有比目前所見更多的維度

And this is an experiment that may test for them in our lifetime.

將有個能於此生完成的對撞實驗來驗證它們

Amazing possibility.

充滿了驚嘆的可能性

Thank you very much.

非常謝謝大家

(Applause)

(掌聲)