Murray Gell-Mann: Beauty and truth in physics

翻译人员: li shuo 校对人员: Wang Qian

Thank you for putting up these pictures of my colleagues over here.

非常感谢把我同事的这些照片挂在这儿。

(Laughter) We'll be talking about them.

（众笑）我们待会就会谈到他们

Now, I'm going try an experiment. I don't do experiments, normally. I'm a theorist.

现在我来做个实验。我平常不做实验，只搞理论研究。

But I'm going see what happens if I press this button.

来看看我按下这按钮会怎样。

Sure enough. OK. I used to work in this field of elementary particles.

好吧。我过去的科研方向是基本粒子。

What happens to matter if you chop it up very fine?

如果你把它再分下去会怎样呢？

What is it made of?

它是由什么组成的呢？

And the laws of these particles are valid throughout the universe,

宇宙中这些基本粒子所遵循的物理规律都是一致的，

and they're very much connected with the history of the universe.

它们和宇宙的历史息息相关。

We know a lot about four forces. There must be a lot more,

对基本粒子的四种作用力我们已经相当了解，但未知的部分肯定更多。

but those are at very, very small distances,

但对极其微小尺度的物质

and we haven't really interacted with them very much yet.

我们还所知甚少。

The main thing I want to talk about is this:

我最想说的就是

that we have this remarkable experience in this field of fundamental physics

在基础物理领域我们有这个显著的经验：

that beauty is a very successful criterion for choosing the right theory.

美是我们在判断理论正确与否时的一条十分有用的标准

And why on earth could that be so?

但原因何在呢？

Well, here's an example from my own experience.

先让我讲一个我自己的经历吧。

It's fairly dramatic, actually, to have this happen.

它非常有戏剧性。

Three or four of us, in 1957,

在1957年，我们三四位同僚一起

put forward a partially complete theory of one of these forces, this weak force.

提出了一个还算完整的弱相互作用理论。

And it was in disagreement with seven -- seven, count them, seven experiments.

这理论和当时7个实验结果都不吻合--足足七个，大家想想看！

Experiments were all wrong.

后来知道那些实验都是错的。

And we published before knowing that,

虽然我们当时并不知道后来知道那些实验都是错的，我们还是出版了我们的理论。

because we figured it was so beautiful, it's gotta be right!

因为我们认为这个理论太美了，它必定是对的。

The experiments had to be wrong, and they were.

那些那些实验必须是错的，它们的确也是错的。

Now our friend over there, Albert Einstein,

我们的朋友爱因斯坦，他在那儿

used to pay very little attention when people said,

听到别人说D.C.米勒的实验结果与他的狭义相对论不符时

"You know, there's a man with an experiment that seems to disagree with special relativity.

他完全不放在心上，

DC Miller. What about that?" And he would say, "Aw, that'll go away." (Laughter)

他会说：“哦，那实验肯定是错的！” （众笑）

Now, why does stuff like that work? That's the question.

为什么事情是这样的呢？这是个问题。

Now, yeah, what do we mean by beautiful? That's one thing.

物理学中的美到底是什么呢？这是一方面。

I'll try to make that clear -- partially clear.

我会尽量说清楚究竟什么是物理中的美。

Why should it work, and is this something to do with human beings?

为什么它在物理中有很大作用，以及这是不是和人类自身有关呢？

I'll let you in on the answer to the last one that I offer,

我先回答最后一个问题

and that is, it has nothing to do with human beings.

这和人类一点关系都没有。

Somewhere in some other planet, orbiting some very distant star,

假设在遥远的星系的一颗行星上

maybe in a another galaxy,

也许在另一个银河系

there could well be entities that are at least as intelligent as we are,

存在着至少和我们一样聪明的智慧生物

and are interested in science. It's not impossible; I think there probably are lots.

他们同样对科学感兴趣。这并不是不可能的。我想也许存在很多这样的星球。

Very likely, none is close enough to interact with us.

但它们十分有可能离我们太遥远了，以至于无法和我们交流。

But they could be out there, very easily.

但很大可能，他们的确存在。

And suppose they have, you know, very different sensory apparatus, and so on.

假设他们拥有和我们不同的感觉器官，比方说

They have seven tentacles, and they have 14 little funny-looking compound eyes,

他们有7只触手，14个可笑的小复眼

and a brain shaped like a pretzel.

和一个形似蝴蝶结的大脑。

Would they really have different laws?

他们会有不同的物理规律吗？

There are lots of people who believe that, and I think it is utter baloney.

很多人坚信有，可我认为这纯属胡扯。

I think there are laws out there,

我想那里存在一些物理规律

and we of course don't understand them at any given time very well

尽管我们也还不能透彻了解全部的规律

-- but we try. And we try to get closer and closer.

但我们会努力去了解它们。我们努力去接近它们。

And someday, we may actually figure out the fundamental unified theory

也许终有一天，我们会找出宇宙中，关于粒子和力

of the particles and forces, what I call the "fundamental law."

基本又统一的定律，我管它叫“基本定律”

We may not even be terribly far from it.

也许现在我们离发现这个定律也并非那么遥远。

But even if we don't run across it in our lifetimes,

即便在有生之年我们看不到这一天

we can still think there is one out there,

我们仍然可以坚信它的存在

and we're just trying to get closer and closer to it.

我们所做的就是不断接近它。

I think that's the main point to be made.

PPT上是我接下来要阐述的观点（以数学简洁表达出来的理论，就是美和优雅的。）

We express these things mathematically.

我们用数学描述理论

And when the mathematics is very simple --

而数学是简明的

when in terms of some mathematical notation,

就一些数学符号而言

you can write the theory in a very brief space, without a lot of complication --

你可以把一个理论简洁的表示出来，一点也不复杂

that's essentially what we mean by beauty or elegance.

这种理论就是美丽和优雅的

Here's what I was saying about the laws. They're really there.

这也就是我说“基本定律”，他们的确是存在的。

Newton certainly believed that.

牛顿肯定也持这一观点。

And he said, here, "It is the business of natural philosophy to find out those laws."

他说：“自然哲学（在牛顿时代，自然哲学=科学）的目标就是发现自然界的基本规律。”

The basic law, let's say -- here's an assumption.

这里有一个关于基本定律的假设

The assumption is that the basic law really takes the form

基本定律是

of a unified theory of all the particles.

关于所有粒子的一种统一理论。

Now, some people call that a theory of everything.

有些人称其为“万有理论”

That's wrong because the theory is quantum mechanical.

那不对，因为那个理论是关于量子力学的。

And I won't go into a lot of stuff about quantum mechanics and what it's like, and so on.

我不会讲一些关于量子力学的知识，比如什么是量子力学之类。

You've heard a lot of wrong things about it anyway. (Laughter)

你们一定听说过很多关于量子力学的错误说法。（众笑）

There are even movies about it with a lot of wrong stuff.

甚至还有几部与之相关的电影，里面也是错误百出。

But the main thing here is that it predicts probabilities.

但最主要的是量子力学能预测可能性。

Now, sometimes those probabilities are near certainties.

有时它的预测是接近正确的

And in a lot of familiar cases, they of course are.

在很多常见的情况下，他们一定如此

But other times they're not, and you have only probabilities for different outcomes.

但在其他时候则未必，你能获知的只是各种可能性而已。

So what that means is that the history of the universe is not determined just by the fundamental law.

因此，这说明决定宇宙的历史不仅仅有基本定律。

It's the fundamental law and this incredibly long series of accidents,

它们应包括基本定律和不确定性，

or chance outcomes, that are there in addition.

还有偶发事件

And the fundamental theory doesn't include those chance outcomes; they are in addition.

而基本定律可不包括这些结果，他们是额外附加的。

So it's not a theory of everything. And in fact, a huge amount of the information

所以基本定律不是万有理论。事实上，我们周围宇宙中

in the universe around us comes from those accidents,

大量的信息从这些不确定性而来，

and not just from the fundamental laws.

而并非来自基本定律。

Now, it's often said that getting closer and closer

现在人们总是说，通过以下方法来接近基本定律

to the fundamental laws by examining phenomena at low energies, and then higher energies,

先是在低能量下，然后是高能量下观察现象

and then higher energies, or short distances, and then shorter distances,

接着是更高能量，小尺度，更小的尺度

and then still shorter distances, and so on, is like peeling the skin of an onion.

再小的尺度，就像 剥洋葱皮一样。

And we keep doing that,

我们的确一直这么做。

and build more powerful machines, accelerators for particles.

建造更强的机器来加速粒子

We look deeper and deeper into the structure of particles,

我们不断深入到粒子的更微小的结构当中，

and in that way we get probably closer and closer to this fundamental law.

这样我们可能会更接近基本定律。

Now, what happens is that as we do that, as we peel these skins of the onion,

当我们剥下这些洋葱皮

and we get closer and closer to the underlying law,

从而接近下一层的定律时，

we see that each skin has something in common with the previous one,

我们发现每一层洋葱皮和它前一层

and with the next one. We write them out mathematically,

、后一层之间都存在共性。当我们用数学把它们表示出来时

and we see they use very similar mathematics.

我们发现他们使用的数学是相似的。

They require very similar mathematics.

他们需要十分相似的数学。

That is absolutely remarkable, and that is a central feature

那绝对是惊人的发现，

of what I'm trying to say today.

那也正是我今天最想说的。

Newton called it -- that's Newton, by the way -- that one.

牛顿称它为...,顺便说一下那就是牛顿

This one is Albert Einstein. Hi, Al! And anyway,

这是爱因斯坦。你好，小爱。无论怎样，

he said, "nature conformable to herself" -- personifying nature as a female.

他说:"大自然是自适应的。"（并赋予自然以女性的形象）

And so what happens is that the new phenomena,

这个新现象

the new skins, the inner skins of the slightly smaller skins of the onion

新的"洋葱皮"，洋葱内小的那层

that we get to, resemble the slightly larger ones.

当我们接近它时，它就像大的那些层。

And the kind of mathematics that we had for the previous skin

关于之前一层“洋葱皮”的数学机制

is almost the same as what we need for the next skin.

和后面的一层几乎一样。

And that's why the equations look so simple.

这就是为什么这些方程看起来如此简单。

Because they use mathematics we already have.

因为它们使用的数学是我们已经熟知的。

A trivial example is this: Newton found the law of gravity,

这有一个小例子：牛顿发现了万有引力定律

which goes like one over the square of the distance between the things gravitated.

万有引力的大小与物体间距离的平方成正比

Coulomb, in France, found the same law for electric charges.

法国的库伦发现电荷间的作用也遵循同样的规律。

Here's an example of this similarity.

这就是相似性的一个例子。

You look at gravity, you see a certain law.

当你看万有引力时，你会看到一定的定律。

Then you look at electricity. Sure enough. The same rule.

而当你看电荷间的作用时，你将会发现相同的规律。

It's a very simple example.

这是一个非常简单的例子。

There are lots of more sophisticated examples.

还有更多复杂的例子。

Symmetry is very important in this discussion.

对称性在这里是非常重要的。

You know what it means. A circle, for example,

你们对此一定很了解。举个例子来说，一个圆

is symmetric under rotations about the center of the circle.

绕中心旋转是对称的。

You rotate around the center of the circle, the circle remains unchanged.

你绕圆心旋转，圆会保持不变。

You take a sphere, in three dimensions, you rotate around the center of the sphere,

当你绕着一个三维的球旋转时

and all those rotations leave the sphere alone.

所有这些旋转都不会使球发生变化

They are symmetries of the sphere.

它们就是球的对称性。

So we say, in general, that there's a symmetry

所以大体上来说，

under certain operations if those operations leave the phenomenon,

如果一个物体或一种现象经过某种操作后能够保持不变，

or its description, unchanged.

那么它就具有对称性。

Maxwell's equations are of course symmetrical

麦克斯韦方程就具有这种对称性，

under rotations of all of space.

在空间旋转的条件下。

Doesn't matter if we turn the whole of space around by some angle,

无论我们把空间旋转怎样一个角度，

it doesn't leave the -- doesn't change the phenomenon of electricity or magnetism.

电和磁的显现都不会改变。 电和磁的显现都不会改变。 它都不会改变电磁现象。

There's a new notation in the 19th century that expressed this,

19世纪出现了一种新的符号法则来表达麦克斯韦方程，

and if you use that notation, the equations get a lot simpler.

如果你使用那套符号，麦克斯韦方程组会变得更加简洁。

Then Einstein, with his special theory of relativity,

爱因斯坦的狭义相对论

looked at a whole set of symmetries of Maxwell's equations,

关注的是麦克斯韦方程体系的整体对称性。

which are called special relativity.

这被称之为狭义相对论

And those symmetries, then, make the equations even shorter, and even prettier, therefore.

这些对称使得麦克斯韦方程组更简洁，更加漂亮。

Let's look. You don't have to know what these things mean, doesn't make any difference.

让我们看看幻灯片。你们并不用知道这些公式具体的含义是什么，这没什么大影响，

But you can just look at the form. (Laughter) You can look at the form.

你只需看它们的形式就行啦（众笑）。让我们看一下它的形式。

You see above, at the top, a long list

你们可以看到，在上方，很长的一列

of equations with three components for the three directions of space: x, y and z.

这是一系列具有xyz三个空间分量的方程组。

Then, using vector analysis, you use rotational symmetry, and you get this next set.

用矢量分析，利用对称性，你们会看到接下来这种形势。

Then you use the symmetry of special relativity and you get an even simpler set

当你使用狭义相对论的对称形式时，你就会得到一种更加简洁的形式。

down here, showing that symmetry exhibits better and better.

它显示对称性越来越好

The more and more symmetry you have, the better you exhibit the simplicity and elegance of the theory.

越是对称，你的理论就会呈现出更加简洁和优雅的形式。

The last two, the first equation says that electric charges and currents

我们来看最后两个方程，第一个方程说明

give rise to all the electric and magnetic fields.

电荷和电流是怎样产生电场和磁场的，

The next -- second -- equation says that there is no magnetism other than that.

接下来的一个方程说明除了磁场之外没有别的东西了。

The only magnetism comes from electric charges and currents.

磁场唯一的来源就是电荷和电流。

Someday we may find some slight hole in that argument.

也许有一天我们会发现这些理论中的小小不足

But for the moment, that's the case.

但就现在看来，这种理论还是正确的。

Now, here is a very exciting development that many people have not heard of.

现在有一个很多人都没有听说过的令人兴奋的发展。

They should have heard of it, but it's a little tricky to explain in technical detail,

他们应当听说过它，但是把它解释清楚需要一些技巧，

so I won't do it. I'll just mention it. (Laughter)

所以我不准备这么做了。我就是稍微提一下。

But Chen Ning Yang, called by us "Frank" Yang -- (Laughter)

杨振宁，我们叫他 夫兰克 杨

-- and Bob Mills put forward, 50 years ago,

和罗伯特-米尔斯，在50年前提出的

this generalization of Maxwell's equations, with a new symmetry.

这种对麦克斯韦方程组的概括有全新的对称性。

A whole new symmetry.

一种全新的对称。

Mathematics very similar, but there was a whole new symmetry.

在数学上很相似，但这是一种全新的对称。

They hoped that this would contribute somehow to particle physics

他们希望这会对粒子物理有某种帮助。

-- didn't. It didn't, by itself, contribute to particle physics.

然而它本身并没有对粒子物理有帮助。

But then some of us generalized it further. And then it did!

但是我们中的一些人把它更进一步的推广了。于是成功了。

And it gave a very beautiful description of the strong force and of the weak force.

它给出一种非常漂亮的方法来描述强相互作用和弱相互作用。

So here we say, again, what we said before:

所以我们说，正如我之前所说的，

that each skin of the onion shows a similarity to the adjoining skins.

正如洋葱皮之间存在着联系一样，

So the mathematics for the adjoining skins is very similar to what we need for the new one.

描述新旧理论的数学也是相似的。

And therefore it looks beautiful

因此它看上去美极了。

because we already know how to write it in a lovely, concise way.

因为我们已经知道用如何把它用漂亮和简明的方式表示出来。

So here are the themes. We believe there is a unified theory underlying all the regularities.

这是所有的主题。我们相信在所有的规律下有一个统一的理论。

Steps toward unification exhibit the simplicity.

在接近统一理论的过程中，呈现出对称性。

Symmetry exhibits the simplicity.

对称性显示出了简洁。

And then there is self-similarity across the scales -- in other words,

在所有的尺度上都存在着自相似性，换句话说

from one skin of the onion to another one.

从洋葱的一层到另一层

Proximate self-similarity. And that accounts for this phenomenon.

大体上来说是自相似的。那就解释了这个现象。

That will account for why beauty is a successful criterion for selecting the right theory.

那也将解释为什么美是选择正确理论的成功准则。

Here's what Newton himself said:

牛顿光学指出：

"Nature is very consonant and conformable to her self."

“自然是和谐和自相似的。”

One thing he was thinking of is something that most of us take for granted today,

他的这种思想在我们今天看来是天经地义的，

but in his day it wasn't taken for granted.

然而在他的那个时代人们可不这么想。

There's the story, which is not absolutely certain to be right, but a lot of people told it.

这有一个故事，这个故事并不一定是真的，但很多人都讲过。

Four sources told it. That when they had the plague in Cambridge,

它有四个来源。当剑桥大学爆发瘟疫时，

and he went down to his mother's farm -- because the university was closed --

牛顿回到到他母亲的农场，由于大学停课了

he saw an apple fall from a tree, or on his head or something.

他看到苹果从树上落下来, 砸到了他的脑袋或者其他什么东西，

And he realized suddenly that the force that drew the apple down to the earth

他突然意识到这种把苹果吸向地面的力

could be the same as the force regulating the motions of the planets and the moon.

很有可能和规范月球和行星运动的力是一致的

That was a big unification for those days, although today we take it for granted.

虽然今天看来这是无可厚非的，在那个年代，这是一个伟大的统一。

It's the same theory of gravity.

它就是万有引力定律。

So he said that this principle of nature, consonance:

所以他说，自然界的原理，和谐

"This principle of nature being very remote from the conceptions of philosophers,

这种自然法则与哲学家的观念相距甚远。

I forbore to describe it in that book,

我克制自己没有把这种想法写进我的书里，

lest I should be accounted an extravagant freak ... "

除非我想被认为是一个奢侈的怪胎

That's what we all have to watch out for, (Laughter) especially at this meeting.

对一点我们都十分小心。（众笑）特别是在这个会议上。

" ... and so prejudice my readers against all those things which were the main design of the book."

“我的读者对本书的主要内容怀有偏见”。

Now, who today would claim that as a mere conceit of the human mind?

谁想被视为一个妄想狂呢？

That the force that causes the apple to fall to the ground

把苹果吸向地面的力

is the same force that causes the planets and the moon to move around,

很有可能和使月球和行星运动的力是一致的，

and so on? Everybody knows that. It's a property of gravitation.

等等？每个人都知道。它就是万有引力的性质。

It's not something in the human mind. The human mind can, of course, appreciate it

它并不是人们头脑中的思想。当然人类的思想可以理解它，

and enjoy it, use it, but it's not -- it doesn't stem from the human mind.

欣赏它，使用它。但它并非来自于人类的思维。

It stems from the character of gravity.

它来自于万有引力的性质。

And that's true of all the things we're talking about.

那对我们所谈论的一切都是对的。

They are properties of the fundamental law.

它们是基本定律的性质。

The fundamental law is such that the different skins of the onion resemble one another,

基本定律就像一层一层的相似的洋葱皮。

and therefore the math for one skin allows you to express beautifully and simply

因此用来描述“一层洋葱皮”的数学可以优美并且简单的

the phenomenon of the next skin.

表述另外一层。

I say here that Newton did a lot of things that year:

那一年牛顿做出了很多贡献：

gravity, the laws of motion, the calculus, white light composed of all the colors of the rainbow.

万有引力定律，牛顿运动定律，微积分，并发现白光是由类似彩虹的不同颜色的光组成的。

And he could have written quite an essay on "What I Did Over My Summer Vacation."

他应该写一篇论文，题目就叫做“我在暑假都干了什么”

(Laughter)

（众笑）

So we don't have to assume these principles as separate metaphysical postulates.

因此我们不需要假定这些原则是独立的抽象假设。

They follow from the fundamental theory.

它们是由基本定律推导出的。

They are what we call emergent properties.

我们称之为涌现性。

You don't need -- you don't need something more to get something more.

我们不需要一些东西来得到更多的东西。

That's what emergence means.

这就是涌现性的含义。

Life can emerge from physics and chemistry, plus a lot of accidents.

生命源于物理和化学，再加上很多意外。

The human mind can arise from neurobiology and a lot of accidents,

人类的智慧源于神精细胞和很多意外因素。

the way the chemical bond arises from physics and certain accidents.

这些化学作用源于物理和特定的意外因素。

It doesn't diminish the importance of these subjects

这并不会较少其重要性，当

to know that they follow from more fundamental things, plus accidents.

了解到它们遵循基本定律和一些意外因素

That's a general rule, and it's critically important to realize that.

那是一个大体上的原则，意识到这点很重要。

You don't need something more in order to get something more.

你不需要更多的东西来得到更多的东西。

People keep asking that when they read my book, "The Quark and the Jaguar,"

当人们读我的书《夸克和美洲豹》，他们总是禁不住要问。

and they say, "Isn't there something more beyond what you have there?"

他们说：除了你说的那些以外，还有其他更多的吗？

Presumably, they mean something supernatural.

他们很可能在问是否存在超自然。

Anyway, there isn't. (Laughter)

无论怎样它不存在。（众笑）

You don't need something more to explain something more.

你不需要更多的东西来解释更多的东西。

Thank you very much. (Applause)

非常感谢。（众笑）