Economist, 经济学人杂志。是一份由伦敦经济学人报纸有限公司出版的杂志，于1843年9月由詹姆士·威尔逊创办。杂志的大多数文章写得机智，幽默，有力度，严肃又不失诙谐，并且注重于如何在最小的篇幅内告诉读者最多的信息。同时，《经济学人》也是极好的雅思阅读课外读物，很多时候，雅思阅读考试的文章就是出自其中。可以说经济学人相比较于其他国内外语报纸的态度更客观，视角更宽。今天为大家带来的这篇阅读素材是来自该杂志的一篇文章，并且帮大家附上详细的中文翻译，希望对大家的阅读能力有所帮助。
Using maths to explain the universe 用数学解释整个宇宙
LEONARD SUSSKIND is a professor of theoretical physics at Stanford University and director of the Stanford Institute for Theoretical Physics. He is regarded as one of the fathers of string theory, a somewhat controversial attempt to explain physics using a single mathematical framework.
伦纳德-萨斯坎德是斯坦福大学的理论物理学教授兼斯坦福理论物理研究所的主任.人们认为他是弦理论的开创者之一，该理论试图利用单一的数学框架解释物理学，存在一定的争议。
He is the author of several popular-science books about matters cosmological. His new book, “The Theoretical Minimum”, co-written with George Hrabovsky, an amateur physicist, is a primer for readers who want to know how to think like a physicist.
他撰写了若干本宇宙学的大众科学读物。他的新书《理论最小值》是与业余物理学家乔治-拉博夫斯基合作完成的，读者若想学习如何像物理学家一样思想，这本书可作为入门读物。
Can you outline what we know about string theory? 请你概括一下我们对弦理论的了解？
The most important single thing about string theory is that it’s a highly mathematical theory and the mathematics holds together in a very tight and consistent way. It contains in its basic structure both quantum mechanics and the theory of gravity. That’s big news.
弦理论最重要的一点是，它是一个高度数学化的理论，在整个理论中数学结合的方式非常严密和一致。量子力学和万有引力理论都包含在弦理论的基本结构中。这点非常重要。
Why?为什么呢？
Basically, from the time of Einstein’s [theory of] general relativity there was no good idea about how quantum mechanics and gravity fit together. They were always at each other’s throat, apparently inconsistent. String theory’s biggest and most important impact is to show that gravity and quantum mechanics can and do fit together. That, more than anything else, has maintained interest in it.
简单来说,爱因斯坦提出广义相对论时，当时并没有能把量子力学和万有引力统一起来的好理论。量子力学和引力总是相互矛盾，明显不能统一。弦理论最大、也是最重要的影响在于,它显示引力和量子力学是可以统一的,并且确实是统一的。这一点比弦理论的其余方面都更引人注目。
String theory presumes the existence of extra spatial dimensions. How do we know they exist?
弦理论假设有更高的空间维度存在.我们怎么知道它们存在？
It must be so because it is so deeply embedded in the mathematics and not easy to explain. I pride myself on being able to explain things to a broad audience, but sometimes you have to say it’s buried in the mathematics. [The theory] just doesn’t work unless you add six more dimensions to the world and we’ll have to leave it at that.
其他维度肯定是存在的,因为它深深根植在数学之中,而且不太容易解释。我对自己向广大观众解释问题的能力引以为豪,但有时必须得说,它就深藏在数学里。除非你给宇宙额外加上6个维度，否则(该理论)根本就不能用,我们只能这样了。
Okay, but why have we been unaware of them until now? 好吧,但为什么直到现在我们才开始意识到它们存在？
Because they’re tiny. 因为它们很小很小。
So, we can’t understand these dimensions because they are too small? 就是说,因为这些维度太小了所以我们无法理解? Yes. 是的。
And what difference do the dimensions make to the layperson’s understanding of the universe?
这些空间维度和普通人对宇宙的理解有什么区别？
These extra dimensions can be arranged and put together in many different patterns, in a variety of different ways. Not billions, trillions or quintillions of ways, but many more than that. The ways these dimensions are put together into these tiny little spaces determine how particles will behave, what particles will exist, what the constants of nature are—quantities like dark energy or the electric charge of an electron. In string theory all those things are features of the ways that these tiny dimensions are put together. The tiny dimensions are like the DNA of the universe.
这些额外的空间维度能以许多不同的样式排列和组合起来,方法多种多样.十亿,万亿,百万兆种方法都不止,比这还要多得多.这些维度在微小的空间内如何组合，决定了粒子会如何表现，会有什么粒子存在，无量纲物理常数是多少——即暗能量或者电子电荷的量是多少,诸如此类。在弦理论中，这些东西都是微小的空间维度按照一定组合方式后产生的特性。这些微小的维度就像是宇宙的DNA。
Yet there are physicists who don’t think string theory is correct. 但有物理学家认为弦理论是错误的。
Oh, well, I suppose there are! We don’t know if string theory is true. 噢，好吧，我想肯定有!我们也不知道弦理论是不是正确的。
I thought you said the maths stacks up? 我想你之前说过弦理论数学上能自圆其说？
There is a difference between mathematical internal consistency and whether or not it describes nature. We can write mathematical theories that are not the right theory of nature—geometry, for example. There’s Euclid’s geometry; positive curve geometry; the geometry of a sphere. Which is the right geometry of space? They’re all consistent, mathematically uncontradictory. But it’s a different thing to say a mathematical theory is consistent and that it describes the real world.
一种理论，其数学的内在一致性，和它是否正确描述自然是有区别的。我们可以写出在自然界中不适用的数学理论——比方说，在几何学里，有欧几里得几何；正曲线几何;球面几何。哪一种几何是适用于空间呢？它们全都具有一致性，数学上无懈可击。但某个数学理论具有一致性和它能够描述真实世界完全就是两码事。
How could we find out whether string theory describes nature or not? 我们怎样知道弦理论是否描述自然？
If they can co-exist with each other. If that’s all string theory does then it’s still an enormous conceptual advance.
看二者能否并存。如果弦理论仅仅是和自然并存而已，它概念上仍是一个巨大的进步。
Unless it isn’t true; in which case gravity and quantum mechanics aren’t related. 除非它是错误的;这样的话引力和量子力学就不统一了。
Well, right, but they have to be related because they both exist in the same world. 呃，对，但引力和量子力学必须是统一的，因为它们存在于同一个宇宙。
What is dark energy?暗能量是什么？
It is the energy of empty space. It’s there just because empty space is there. If you have a box full of particles, each particle has an energy MC2, then you stretch the sides of the box and make it bigger and the energy dilutes, meaning that the energy density goes down. Dark energy doesn’t thin out. You expand the box but the amount of energy per unit volume remains the same.
就是真空的能量。因为真空存在，所以暗能量就存在。如果你有一个装满了粒子的盒子，每个粒子的能量是MC2，然后你把盒子的各个面拉长，扩大它的体积，于是能量被稀释了，意味着能量密度就下降了。但暗能量不会被稀释。你的盒子膨胀了，单位体积的(暗)能量大小仍保持一致。
Does it definitely exist and can you measure it? 暗能量绝对存在吗?可以测量吗？
Yes, it exists. We have measured it by the expansion of the universe. Energy is what causes the universe to expand, and the way that it dilutes as it expands controls how fast it expands and the detailed way in which it expands. There is an absolute 100% confirmation of the idea that dark energy exists.
是的，暗能量是存在的。你可以通过宇宙膨胀来测量。能量是导致宇宙膨胀的原因，而能量是如何稀释的，控制着宇宙膨胀速度的快慢，以及宇宙膨胀的具体方式。暗能量的存在是绝对100%确定的。
Where did it come from and what is it doing? 暗能量从哪来?有什么作用？
Since the birth of quantum mechanics physicists understood that quantum field theory—the basic underlying theory of quantum mechanics, of electrons and photons and all those things—should provide every tiny bit of space with a huge amount of this undiluting kind of energy. That energy should gravitate. They understood that and they did not understand why this source of gravitation didn’t seem to turn the universe into an incredibly rapidly expanding universe that would double in size every ten to the minus 42 seconds.
自从量子力学诞生以来，物理学家就认识到，量子场论——量子力学，电子和光子等微观物体的基础理论——应该为空间的每个微小片段设置大量这类不会稀释的能量。这种能量还应该产生万有引力。他们懂得这一点，但他们不理解的是，为什么这个引力的来源没有迹象要把这个宇宙变成一个急剧膨胀、体积每过10的负42次方秒就会翻倍的宇宙。
The real question was not “what is dark energy?” it was “where is dark energy?” For many years Einstein and others thought that the dark energy must be zero because it was so tiny. Nobody could detect it and it couldn’t be detected in the expansion of the universe. What was most remarkable was when it was discovered that it was not zero, but it was 123 orders of magnitude smaller.
真正的问题不是“什么是暗能量?”，而是“暗能量在哪?”很多年来，爱因斯坦和其他人都认为暗能量一定是0, 因为它是如此之小。过去没有人能探测到它，并且它也无法从宇宙膨胀中探测到。所以当物理学家发现暗能量不是0，而是小123个数量级时，这成为暗能量领域最值得关注的发现。
Is the universe still expanding? If so, how much can it expand and will it eventually implode?
宇宙现在还在膨胀吗？如果是，它能膨胀到什么地步，会不会最终发生内爆？
No, no, no. Before the dark energy was discovered there were three possibilities: that it would implode, that it would continue to expand or that it would expand at an ever decreasing rate. Once the dark energy was discovered and discovered to be positive it was shown that it will continue to expand.
不不不。在发现暗能量之前，人们假设有三种可能：内爆，继续膨胀，或者膨胀的速度不断下降。一旦发现暗能量确实存在，就说明了宇宙还会继续膨胀。
The equations as we know them now do not seem to permit the possibility that it will implode. As it expands the dark energy won’t dilute. It’s vacuum energy. In every bit of volume there is the same amount, but the electrons, protons or neutrons will spread out, so what we can look forward to is a universe that is completely empty.
我们现今所知的公式没有显示出宇宙有内爆的可能性。宇宙不断膨胀，暗能量也不会稀释。它是真空的能量。在每一个空间小片段里，暗能量都是等量的，但电子、质子和中子会扩散开，所以我们可以预见宇宙最终将完全空无一物。
If the universe is expanding there must be something into which it’s expanding?
如果宇宙正在膨胀的话，一定有什么东西容纳了宇宙膨胀出来的部分？
So the universe isn’t something that can be imagined by a human brain?
所以宇宙不是人脑可以想象的东西？
That’s right. That’s why we’re stuck using abstract mathematics for the simple reason that our visualisation abilities evolved in a certain environment that just wasn’t appropriate for understanding quantum mechanics and general relativity, so we have to get our intuitions from abstract mathematics.
没错。这就是为什么我们一概使用抽象的数学研究问题的原因，原因很简单，我们的想象力是在特定的环境中进化而成的，不适合用来理解量子力学和广义相对论，所以我们必须通过抽象数学培养直觉。
So the universe doesn’t have an outside? 所以说宇宙外面什么都没有？
It doesn’t have an outside or an inside. It just has the rubber surface. You have to learn to think of the surface of the balloon as being all there is. It’s all there is.
宇宙没有“里面”和“外面”之分。它只有一个橡皮表面。你必须学会把整个宇宙看成一个气球的表面。除此之外什么都没有。
Ah-ha! No. You are a victim of your own neural architecture which doesn’t permit you to imagine anything outside of three dimensions. Even two dimensions. People know they can’t visualise four or five dimensions, but they think they can close their eyes and see two dimensions. But they can’t. When you close your eyes and try to see two dimensions you’ll always see a surface embedded in three dimensions.
啊哈!不对。你被自己的神经结构欺骗了，它让你无法想象任何非三维的东西。甚至二维空间都想象不了。人们知道自己无法想象四维或五维空间，但他们以为只要闭上眼睛，就能见到二维空间。但其实不能。当你闭上眼睛试图看到二维空间时，你看到的永远只是三维空间中的一个平面。
Is there something special about three dimensions? No. There is something special about your neural architecture. You evolved in a world where everything inside your brain is hooked up and geared to be able to see three dimensions and nothing else.
难道说三维空间有什么特别之处吗?不是。特别的是你的神经结构。在这个世界里，生物进化让你大脑中的一切，都是固定专门用来感知三维空间的，再没别的了。
