Making sense of string theory | Brian Greene

校对人员: Wang Qian

In the year 1919,

在1919年，

a virtually unknown German mathematician, named Theodor Kaluza

一位显为人知名叫“西奥多•卡鲁扎”的德国数学家

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

提出了一个大胆，甚至有些异乎寻常的猜想。

He proposed that our universe

他认为在我们的宇宙

might actually have more than the three dimensions

可能实际上包含不只三个维度

that we are all aware of.

并非像我们一贯所认为的那样。

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

除了我们熟悉的左和右，前与后，上跟下外，

Kaluza proposed that there might be additional dimensions of space

“卡鲁扎”认为空间里可能包含有额外的维度

that for some reason we don't yet see.

只是因为某些特殊原因，我们还无法认知。

Now, when someone makes a bold and bizarre idea,

当一个人有了大胆怪异的猜想，

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

我们通常只会关注其大胆和古怪的部分，

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

而这部分和我们存在的现实世界是毫无关联的。

This particular idea, however --

但是这一次，面对于这个猜想--

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

虽然我们还不知道它的正确与否，

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

之后我会谈谈一些会在未来几年里进行的实验，

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

可能会证实它的真伪--

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

这个猜想在上个世纪已经给物理学界带来了重大冲击

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

毫无疑问，它会进一步推动大量前沿学科的研究。

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

所以，我想借此机会与你一起探讨一下这些“额外的维度”。

So where do we go?

我们从哪里开始好呢？

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

先让我们谈一些背景知识吧。话说1907年，

This is a year when Einstein is basking in the glow

那年“爱因斯坦”已经成功地

of having discovered the special theory of relativity

发现了狭义相对论

and decides to take on a new project,

并且正计划开启一个新的课题研究--

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

进一步深入地发掘被大家普遍认知的重力的由来。

And in that moment, there are many people around

那时，很多人

who thought that that project had already been resolved.

认为该课题早已被攻克了。

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

“牛顿”已经在17世纪末提出了重力理论

that works well, describes the motion of planets,

该理论可以正确地描述了星球间的运动，

the motion of the moon and so forth,

月亮的运动等等，

the motion of apocryphal of apples falling from trees,

但这个导致苹果坠落的令人质疑的运动，

hitting people on the head.

一直困扰着大家。

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

虽然这些运动都可以运用牛顿理论来描述，

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

但是“爱因斯坦”意识到“牛顿”遗留下了一些未解的东西，

because even Newton had written

甚至“牛顿”本人也提到

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

虽然他明白如何计算“重力”的影响，

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

但是他无法真切地了解“重力”究竟是如何工作的。

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

为什么距离地球9千3百万英里外的太阳，

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

可以影响到地球的运动？

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

太阳是如何超越空旷无极的宇宙来施展它的魔力？

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

这恰恰是“爱因斯坦”想探讨地--

to figure out how gravity works.

究竟“重力”是从何而来。

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

让我们来看看他究竟发现了什么。

So Einstein found

“爱因斯坦”发现

that the medium that transmits gravity is space itself.

传递“重力”的媒介其实就是空间本身。

The idea goes like this:

他的观点是这样的：

imagine space is a substrate of all there is.

想象空间是承载万物的本源。

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

“爱因斯坦”认为在没有任何物质存在的情况下，空间是细致扁平的。

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

但在有物质存在的情况下， 比如说太阳，

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

它会导致这个类似织布的空间扭曲。

And that communicates the force of gravity.

而这导致了“重力”的产生。

Even the Earth warps space around it.

地球同样会扭曲在它四周的空间。

Now look at the Moon.

你看月亮。

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

根据这个想法，月亮之所以能保持在它的轨道上，

because it rolls along a valley in the curved environment

是因为它沿着曲面的内测旋转

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

太阳，地球，月亮间的影响力均是因为它们本身的存在而产生的。

We go to a full-frame view of this.

我们来总体看一下。

The Earth itself is kept in orbit

地球之所以保持在其轨道上

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

是因为它旋转的曲面是

because of the Sun's presence.

太阳的存在而产生的。

That is this new idea about how gravity actually works.

这是一个崭新的关于“重力”由来的观点。

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

随后，这个观点在1919年通过天文观测被肯定。

It really works. It describes the data.

这个观点能够正确的解释相关的数据。

And this gained Einstein prominence around the world.

这使得“爱因斯坦”在世界上名声大震。

And that is what got Kaluza thinking.

而这也促使了“卡鲁扎”去思考。

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

他和“爱因斯坦”一样，也在寻找我们称之的“统一理论”。

That's one theory

一个理论

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

能够用来描述所有自然间的作用力，可以是一整套观点，

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

一整套法则，或者一条主宰万物的等式，用你的话来说。

So Kaluza said to himself,

所以“卡鲁扎”自认为，

Einstein has been able to describe gravity

“爱因斯坦”能够用扭曲的空间来

in terms of warps and curves in space --

描述“重力”--

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

更精确的来说，用空间和时间。

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

也许我也可以用相同的方式来描述其他已知的作用力，

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

也就是当时已经被认知的电磁力--

we know of others today, but at that time

今天我们知道有更多的作用力，但在那个时期

that was the only other one people were thinking about.

电磁力是另一个唯一被大众所思索的。

You know, the force responsible for electricity

你看，这种作用力反应了电场

and magnetic attraction and so forth.

和磁场的相互作用。

So Kaluza says, maybe I can play the same game

所以“卡鲁扎”认为，也许我可以用相同的方式

and describe electromagnetic force in terms of warps and curves.

同样以“扭曲”为基点来描述电磁力。

That raised a question: warps and curves in what?

于是就有了进一步的问题：“扭曲”的依托是什么？

Einstein had already used up space and time,

“爱因斯坦”已经借用了空间和时间，

warps and curves, to describe gravity.

并以其“扭曲”的结果来描述重力。

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

似乎没有什么别的什么依托对象来实施“扭曲”了。

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

于是“卡鲁扎”想，这样吧，也许空间里包含有更多的维度。

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

他想，如果我要描述另一个作用力，

maybe I need one more dimension.

也许我需要增加一个维度。

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

所以他想象这个世界是由四个维度的空间组成，而不是三个，

and imagined that electromagnetism was warps and curves

并且电磁力的作用是在第四维度上

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

的“扭曲”而产生的。请注意这里：

when he wrote down the equations describing warps and curves

当他在写方程式组来描述四度空间的“扭曲”，

in a universe with four space dimensions, not three,

不再是三度空间的时候，

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

他发现“爱因斯坦”以三度空间为模型构建的方程式组--

those were for gravity --

就是用来描述重力的--

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

因其添加了额外的一维空间而增加了一个方程式。

And when he looked at that equation,

当他查看这个方程式时，

it was none other than the equation

发现没有别的方程式

that scientists had long known to describe the electromagnetic force.

被其他的科学家用来描述这个被熟知的电磁力。

Amazing -- it just popped out.

太奇妙了--就这样被发现了。

He was so excited by this realization

对于这个发现，他万分激动

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

他围绕着房子边跑边叫，“成功喽！”--

that he had found the unified theory.

他已经发现了“统一理论”。

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

很明显，“卡鲁扎”极为地偏重“理论”。

He, in fact --

他，实际上--

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

有一个故事，当他想要学习游泳的时候，

he read a book, a treatise on swimming --

他读了本论述游泳的书--

(Laughter)

（大笑声）

-- then dove into the ocean.

--然后就跳到海里去了。

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

他就是这种将生命系于理论的人。

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

你看，想我们这些稍微有些实践头脑的人，

two questions immediately arise from his observation.

就他的研究上，两个问题会立即产生。

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

第一个问题：如果空间中含有额外的维度，它们在哪里？

We don't seem to see them.

似乎我们并没有观察到。

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

第二个问题：这个理论确实能真实详尽地

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

应用于我们的世界么？

Now, the first question was answered in 1926

第一个问题在1926年被

by a fellow named Oskar Klein.

一个名叫“奥斯卡 克莱恩”的回答了。

He suggested that dimensions might come in two varieties --

他认为维度可能以两种形式存在--

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

一种维度可能很大，很容易被认知，

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

另一种可能很小，卷曲在一起的维度，

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

因为卷曲得太小了，虽然存在于我们周围，

that we don't see them.

但我们无法认知。

Let me show you that one visually.

请看这里的图像演示。

So, imagine you're looking at something

设想你正在关注

like a cable supporting a traffic light.

一根支持交通灯的钢缆。

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

是在曼哈顿。你正在中央公园-- 好像跑题了--

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

从远处看，钢缆貌似是一维的，

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

但大家都知道钢缆是有粗细之分的。

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

虽然从远处来看是非常难辩认的。

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

但如果我们聚焦来看，比如，

a little ant walking around --

一只小蚂蚁在上面爬行着--

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

因为蚂蚁的微小，它可以穿越不同的维度--

the long dimension,

长的维度，

but also this clockwise, counter-clockwise direction.

同样顺时针和逆时针的方向。

And I hope you appreciate this.

同时，我希望你们能感激我们所做的。

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

我们费了很大功夫才让蚂蚁做到了这些。

(Laughter)

（大笑声）

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

但这却阐明了维度可以有两种类型的事实：

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

大的和小的。 大的维度就存在于我们的周围

are the ones that we can easily see,

我们可以轻易的识别，

but there might be additional dimensions curled up,

但也可能存在有额外的卷曲维度，

sort of like the circular part of that cable,

就像钢缆的柱面，

so small that they have so far remained invisible.

因为过于微小而未被发掘。

Let me show you what that would look like.

让我们来看看它可能的形状。

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

如果我们要看空间本身--

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

当然，在屏幕上只能显示两个维度。

Some of you guys will fix that one day,

将来你们之中的一些人会解决这个问题，

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

当然任何不处于平面上的部分是在一个新的维度上，

goes smaller, smaller, smaller,

让我们深入，深入，再深入，

and way down in the microscopic depths of space itself,

一直深入到细微的空间本身--

this is the idea,

这里是关键：

you could have additional curled up dimensions --

空间里可以包含额外的卷曲维度。

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

这就是小圆环--因为太小了所以我们无法观察到。

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

但如果你是超微小的爬行蚂蚁，

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

你既可以在我们公认的大维度上爬行--

that's like the grid part --

就像在这些格子里--

but you could also access the tiny curled-up dimension

也可以在微小的卷曲维度里自由进出

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

因为它实在太微小了，我们无法用肉眼直接看到

or even with any of our most refined equipment.

甚至用我们最精良的仪器也无法观测到。

But deeply tucked into the fabric of space itself,

但当深入到类似织布的空间本身，

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

可能会存在更多的维度，正像我们刚才看到的。

Now that's an explanation

而这就是解释

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

为什么宇宙中能够包含有更多的维度而并非我们所习惯认知的。

But what about the second question that I asked:

那么对于我刚才提出的第二个问题：

does the theory actually work

这个理论能够

when you try to apply it to the real world?

被运用于实践么？

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

其实，“爱因斯坦”，“卡鲁扎”以及其他

worked on trying to refine this framework

致力于优化这个体系

and apply it to the physics of the universe

并试图将其应用于当时被认知到的宇宙物理学，

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

发现在细微处该理论并不能反应现状。

In detail, for instance,

在细微处，比如说，

they couldn't get the mass of the electron

他们无法得到与理论计算

to work out correctly in this theory.

相一致的电子数。

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

曾经很多人致力于此研究，但从40年代，确切地说50年代起，

this strange but very compelling idea

这个奇怪但引人入胜的课题

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

关于如何统一物理学法则的想法没落了。

Until something wonderful happened in our age.

直到在我们这个年代，一些奇妙的事情发生了。

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

在我们的时代，物理学家们正在尝试用一种新的理论

is being pursued by physicists such as myself,

来统一物理学，这其中包括我

many others around the world,

也包括世界各地的物理学家

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

这种理论被称作“超弦理论”

And the wonderful thing is that superstring theory

“超弦理论”奇妙之处在于

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

乍一看它和多维度并没有什么关系

but when we study superstring theory,

但是当我们深入研究“超弦理论”的时候

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

我们发现它以一种崭新的方式使这个理念得以复苏

So, let me just tell you how that goes.

下面让我来解释其中的道理

Superstring theory -- what is it?

什么是“超弦理论”？

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

它是一个试图回答以下问题的理论

what are the basic, fundamental, indivisible, uncuttable constituents

在这个世界上，围绕着我们的万事万物都是由什么样的

making up everything in the world around us?

最基本的，不可再分的成分组成的？

The idea is like this.

这个理论的观点是

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

现在来想象一下我们观察一个熟悉的物体，一个烛托里的蜡烛

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

接着想象我们试图弄明白它的构成

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

于是我们展开一段旅程，进入到这个物体的深处来研究它的构成

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

我们到了内部足够深的地方，你看到了原子

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

我们也知道原子并不是最小的单位

They have little electrons that swarm around a central nucleus

我们看到微小的电子紧紧地围绕着中心的原子核

with neutrons and protons.

原子核中有中子和质子

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

而在中子和质子里我们也能发现更小的粒子--夸克

That is where conventional ideas stop.

以上是以被广泛接受的观点

Here is the new idea of string theory.

现在我要讲的是弦理论提出的新观点

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

在那些粒子的深处，还可以发现一些东西

This something else is this dancing filament of energy.

他们是正在舞动的丝状物，携带着能量

It looks like a vibrating string --

这些东西看上去像振动着的弦

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

这就是弦理论从何而来

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

就好像你看到的大提琴上的弦

can vibrate in different patterns,

能以不同的模式振动

these can also vibrate in different patterns.

这些弦也可以以不同模式振动

They don't produce different musical notes.

他们不能产生各种音乐符号

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

然而，他们制造出了围绕在我们周围，这个世界中的不同粒子

So if these ideas are correct,

所以，如果这个理论是正确的话

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

这就是宇宙中极微观世界的情景

It's built up of a huge number

它是由无数

of these little tiny filaments of vibrating energy,

微小的振动能量丝组成的

vibrating in different frequencies.

他们以不同的频率振动着

The different frequencies produce the different particles.

不同的频率产生不同的粒子

The different particles are responsible

不同的粒子保证了

for all the richness in the world around us.

我们这个世界的多样性

And there you see unification,

这样你就看到了统一性

because matter particles, electrons and quarks,

因为不论是物质粒子，电子，夸克

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

还是放射性粒子，光子，引力子，都是由一种实体构成的

So matter and the forces of nature all are put together

自然界中的物质和各种力都是由

under the rubric of vibrating strings.

这些震动着的红色弦组成的

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

这就是我们所说的统一理论

Now here is the catch.

但是问题是

When you study the mathematics of string theory,

当你研究弦理论中的数学时

you find that it doesn't work

你会发现

in a universe that just has three dimensions of space.

它在我们这个只有三维空间的宇宙里是不成立的

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

在四维，五维或六维的世界里也不成立

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

最终，当你研究这些方程，你会发现

only in a universe that has 10 dimensions of space

它只适用于一个有十个空间维度

and one dimension of time.

和一个时间维度的世界

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

这就是以前克鲁兹和卡莱恩的观点

that our world, when appropriately described,

当我们的世界被合理描述的时候

has more dimensions than the ones that we see.

它的维度应该比我们肉眼看得到的要多

Now you might think about that and say, well,

稍加思索，也许你就会说，

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

好，你看，如果真的存在更多的维度，他们又紧紧地蜷缩起来

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

是啊，如果他们真的足够小的话，也许我们确实看不到他们

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

但是如果有一群微小的绿色智人在下面行走

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

你可以想象让他们变得很小，小到我们眼不见他们，就是这样

One of the other predictions of string theory --

这个弦理论做出的一种预言

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

不，这并不是弦理论做出的另一种预言

(Laughter)

（笑声）

But it raises the question:

但是它引发了一个问题

are we just trying to hide away these extra dimensions,

是我们企图把这些额外的维度隐藏起来呢

or do they tell us something about the world?

又或者他们向我们揭开世界的奥秘

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

在接下来的时间里，我会向你们展示这些额外维度的两个特点

First is, many of us believe that these extra dimensions

第一，我们中的很多人都相信这些额外的维度

hold the answer to what perhaps is the deepest question

可以解答也许是理论物理，理论科学中

in theoretical physics, theoretical science.

最深层的问题

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

这个问题就是：当我们环顾这个世界，

as scientists have done for the last hundred years,

在过去的几百年中，科学家们得出

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

大约有20个数字可以有力地描述我们生活的宇宙

These are numbers like the mass of the particles,

这些数字包括粒子的质量

like electrons and quarks, the strength of gravity,

包括电子和夸克，引力的强度

the strength of the electromagnetic force --

电磁力的强度

a list of about 20 numbers

这大约20个数字

that have been measured with incredible precision,

已经被测量的极度精确

but nobody has an explanation

但是没人可以解释

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

为什么这些数字显示现在我们所测量出来的数值

Now, does string theory offer an answer?

那么，弦理论可以给出答案吗

Not yet.

现在还不行

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

但是我们相信关于上诉问题的答案

may rely on the form of the extra dimensions.

有可能有待这些额外维度的形态来解答

And the wonderful thing is, if those numbers

令人称奇的是，如果这些数字

had any other values than the known ones,

换成了其他数值而非现在的数值

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

那么我们熟悉的宇宙就将灰飞烟灭了

This is a deep question.

这是个深奥的问题

Why are those numbers so finely tuned

为什么这些数字被如此精心地调试

to allow stars to shine and planets to form,

使得恒星发光，行星得以形成

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

我们意识到，如果你扰乱这些数字

if I had 20 dials up here

如果我把这个调高20

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

或者我让你上台来搅乱这些数字

almost any fiddling makes the universe disappear.

几乎任何的干扰都会使宇宙消失

So can we explain those 20 numbers?

那么我们可以解释这20个数字吗？

And string theory suggests that those 20 numbers

弦理论认为，这20个数字

have to do with the extra dimensions.

和额外的维度有关系

Let me show you how.

让我来向你们演示

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

所以当我们讨论到弦理论中的额外维度时

it's not one extra dimension,

不是在讨论额外的一个维度

as in the older ideas of Kaluza and Klein.

就像早期卡鲁扎和克莱因的观点

This is what string theory says about the extra dimensions.

这才是弦理论描述的额外维度

They have a very rich, intertwined geometry.

他们有非常多样又错综复杂的几何图样

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

现在你看到的被称为Calabi-Yau形状

name isn't all that important.

名字并不是重点

But, as you can see,

但是你们可以看到

the extra dimensions fold in on themselves

额外的维度嵌入他们之中

and intertwine in a very interesting shape, interesting structure.

缠绕，呈现出一种引人入胜的形状，一个有趣的结构

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

这个观点认为如果这就是这些额外维度的样子

then the microscopic landscape of our universe all around us

那么我们身处的宇宙的在显微镜在呈现的景象

would look like this on the tiniest of scales.

在如此微小的尺度中看上去就是这样的

When you swing your hand,

就在你的一摆手之间

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

你就来回穿梭在这些额外的维度里

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

但是他们太小了，我们不会察觉到

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

那么这20个数字隐含着什么物理意义呢？

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

请这样来想。如果你看着这件乐器，一个法国圆号

notice that the vibrations of the airstreams

你会注意到这些气流的震动

are affected by the shape of the instrument.

受乐器形状的影响

Now in string theory,

在弦理论中

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

所有这些数字反映了弦可以震动的方式

So just as those airstreams

所以就像这些气流

are affected by the twists and turns in the instrument,

是受乐器弯曲旋转的影响

strings themselves will be affected

弦本身也受

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

震动模式的影响。而震动模式是由移动的几何图案决定的

So let me bring some strings into the story.

现在让我来阐述弦理论的原理

And if you watch these little fellows vibrating around --

但是观察这些周围震动的细小物体时--

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

将会有一个时刻--就是这个时候

notice that they way they vibrate is affected

可以注意到他们震动的方式是受

by the geometry of the extra dimensions.

额外维度的几何图形的影响

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

如果我们准确地知道额外维度的形态

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

我们现在还不知道，但是如果我们可以知道

we should be able to calculate the allowed notes,

我们就可以计算出所有可能的模式

the allowed vibrational patterns.

所有可能的震动模式

And if we could calculate the allowed vibrational patterns,

如果我们可以计算出所有可能的震动模式

we should be able to calculate those 20 numbers.

我们就可以计算出这20个数字

And if the answer that we get from our calculations

如果我们计算出的答案

agrees with the values of those numbers

等于这些数字

that have been determined

通过细致精确的实验

through detailed and precise experimentation,

测量并认定的数值

this in many ways would be the first fundamental explanation

这将在很多方面成为首次彻底深入地解释

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

为什么宇宙的结构是现在的样子。

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

现在，我想解决的第二个问题是：

how might we test for these extra dimensions more directly?

我们如何更直接地证明这些额外维度的存在？

Is this just an interesting mathematical structure

这只是一个有可能解释

that might be able to explain

世界上以前未能解释的问题的

some previously unexplained features of the world,

奇妙数学结构？

or can we actually test for these extra dimensions?

又或者我们真的可以证明这些额外额度的存在？

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

我们认为--我也认为，这将是一件激动人心的事情

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

在将来的五年里，我们有可能成功地证明出

for the existence of these extra dimensions.

这些额外维度的存在

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

事情是这样的。在瑞士日内瓦的欧洲粒子研究中心

a machine is being built called the Large Hadron Collider.

我们正在建造一座大型强子对撞机。

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

这个机器会使粒子以接近光速

opposite directions, near the speed of light.

在隧道中反向运动。

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

大量粒子会迎面飞行

so there's a head-on collision.

并且发生碰撞。

The hope is that if the collision has enough energy,

我们希望，如果这些撞击有足够的能量，

it may eject some of the debris from the collision

撞击可能使部分残骸会从我们的维度中

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

喷出，迫使它们进入其他的维度。

How would we know it?

我们是如果知道得呢？

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

我们将测量撞击后的能量，

compare it to the amount of energy before,

将其与撞击前的能量作比较，

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

如果撞击后能量减少了，

this will be evidence that the energy has drifted away.

这就证明了能量发生了逃逸

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

如果它们以我们可以计算出的模式发生逃逸

this will be evidence that the extra dimensions are there.

那我们就证明了额外维度的存在。

Let me show you that idea visually.

让我向你们展示这个想法的视觉成果

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

想象一下现在我们有一种叫做引力子的粒子--

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

我们假设如果真的存在额外维度，

if the extra dimensions are real.

这就是被喷出的残骸。

But here's how the experiment will go.

但以下是这个实验的过程

You take these particles. You slam them together.

你握住这些粒子，把它们攥在一起

You slam them together, and if we are right,

你把它们攥在一起，如果我们是正确的话，

some of the energy of that collision

撞击中的一部分能量

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

将由残骸携带飞入这些额外维度。

So this is the kind of experiment

这就是我们在将来的5年，7年也许10年

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

的时间里将要持续的实验。

And if this experiment bears fruit,

如果这个实验产生了成果，

if we see that kind of particle ejected

如果我们注意到我们所处的维度中能量

by noticing that there's less energy in our dimensions

比之前的能量有所减少

than when we began,

我们就知道某种粒子被喷出

this will show that the extra dimensions are real.

这就证明了额外维度是真正存在的

And to me this is a really remarkable story,

对我来说这是一个伟大的时刻，

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

一个伟大的机遇。回顾历史，牛顿认为的绝对空间--

didn't provide anything but an arena, a stage

他只证明了一个空间，一个宇宙中

in which the events of the universe take place.

事件发生的舞台。

Einstein comes along and says,

当爱因斯坦出现，他告诉我们

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

空间和时间是可以弯曲的，这就是重力

And now string theory comes along and says,

现在弦理论出现并告诉我们

yes, gravity, quantum mechanics, electromagnetism,

对，重力，量子力学，电磁力学

all together in one package,

都可以被统一起来

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

但前提是我们的宇宙拥有更多的维度，多过我们能观察到的

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

也许在我们的有生之年就能看到这个实验证实了他们的存在

Amazing possibility.

如果真的发生， 那将多么令人激动

Thank you very much.

谢谢大家。

(Applause)

（鼓掌声）