Designing a Universe

设计一个宇宙

Like most of his colleagues at the time, Einstein considered the universe to consist of a cloud of stars, the Milky Way, surrounded by vast space. What was beyond? Was the universe infinite? And if so, what stopped a star from drifting so far that it would have nothing to relate to?

就像他当时的大多数同事一样，爱因斯坦认为宇宙由大量恒星、银河及周围的广阔空间组成。宇宙之外有什么？宇宙是无限的吗？如果是这样的话，什么能阻止一颗恒星漂移到与所有物体脱离联系的距离？

To avoid such problems, Einstein set out in 1917 to design a universe without boundaries. In his model, space is bent around to meet itself, like the side of a tin can.

为了避免此类问题，爱因斯坦在1917年建立了无限宇宙模型。在他设立的模型中，空间就像锡罐的侧面一样，能够弯曲触碰到自己。

“I have committed another suggestion with respect to gravitation which exposes me to the danger of being confined to the nut house,” he confided to a friend.

他向一名朋友倾诉，“我提出另一个有关引力的建议，这使我面临被关进疯人院的风险。”

This got rid of the need for troublesome boundaries. But this universe was unstable, and the cylinder would collapse if something didn’t hold its sides apart.

这就不需要设置令人烦恼的边界了。但这个宇宙并不稳定，如果某种东西没有将两边撑住，这个圆柱就会坍缩。

That something was a fudge factor added to the equations Einstein called the cosmological constant. Physically, this new term, denoted by the Greek letter lambda, represented a long-range repulsive force.

这种东西就是爱因斯坦在自己的公式中插入的一种被他称为“宇宙常数”的容差系数。从物理学来看，这个由希腊字母“兰布达”(λ)指代的新名词代表着远距离的排斥力。

The happy result, Einstein thought, was a static universe of the type nearly everybody believed they lived in and in which geometry was strictly determined by matter.

爱因斯坦认为，皆大欢喜的结果就是一个静态宇宙，几乎所有人都认为他们生活在这样一个宇宙中，其中的几何形态完全由物质决定。

But it didn’t last. Willem de Sitter, a Dutch astronomer, came up with his own solution describing a universe that had no matter at all and was flying apart.

但这没能站住脚。荷兰天文学家威廉·德西特(Willem de Sitter)提出了自己的解答，他描述了一个根本不存在物质且正在飞散的宇宙。

“It would be unsatisfactory, in my opinion,” Einstein grumbled, “if a world without matter were possible.”

“我认为，如果说一个没有物质的世界是可能存在的，”爱因斯坦抱怨称。“这是无法令人满意的。”

And then Edwin Hubble discovered that the universe really was expanding.

后来，埃德温·哈勃(Edwin Hubble)发现，宇宙确实在不断膨胀。

If the cosmological constant couldn’t keep the universe still, then forget about it and Mach’s Principle, Einstein said. “It dates back to the time in which one thought that the ‘ponderable bodies’ are the only physically real entities,” he later wrote to the British cosmologist Felix Pirani.

爱因斯坦表示，既然这个宇宙常数不能使宇宙保持静态，那就别考虑它以及马赫原理了。他后来给英国宇宙学家费利克斯 ·皮拉尼(Felix Pirani)写信称，“这可以追溯到人们认为‘有重量的物质’是唯一真实存在的实体的时候。”

But it was too late. Quantum mechanics soon invested empty space with energy. In 1998 astronomers discovered that dark energy, acting just like the cosmological constant, seems to be blowing space-time apart, just as in de Sitter’s universe.

但为时已晚。量子力学很快就表明，真空中存在很多能量。1998年，天文学家发现暗能量就像宇宙常数一样，似乎将空间与时间分离，与德西特描述的宇宙相似。

In fact, most cosmologists agree today that not quite all motion is relative and that space-time does have an existence independent of matter, though it is anything but static and absolute. The best example are gravitational waves, ripples of compression and stretching speeding through empty space at the speed of light.

实际上，大多数宇宙学家如今同意这个观点，即并不是所有运动都是相对的，时空的确独立于物质存在，尽管它不是静态和绝对的。最好的例子就是引力波——以光速超速穿过真空的一波波引力压缩和伸展。

Einstein was back and forth on this. In 1916, he told Schwarzschild they did not exist, then published a paper saying they did. In 1936, he and his assistant did the same flip-flop again.

爱因斯坦在整个问题上摇摆不定。他在1916年告诉史瓦西，引力波并不存在，后来又发表论文称它存在。他和助手在1936年再次改变观点。

Nobody said this was easy, even for Einstein.

没人认为这很简单，即使是对爱因斯坦来说。

He set out to do one thing, namely make all motion relative, Michel Janssen, a science historian at the University of Minnesota, told a Princeton gathering this month. He failed, but in the process succeeded in doing something very interesting, unifying the effects of acceleration and gravity.

明尼苏达大学(University of Minnesota)科学史学家米歇尔·詹森(Michel Janssen)本月在普林斯顿大学参加聚会时表示，爱因斯坦开始做一件事情，就是使所有运动成为相对的。他失败了，但他在这个过程中成功地做了一些有趣的事情，将加速度与引力的效应统一起来。

The story goes to show, he said, that Bob Dylan was right when he sang “there’s no success like failure,” but wrong that “failure is no success at all.”

他表示，这个故事说明，鲍勃·迪伦(BobDylan)那句“没有像失败这样的成功”是对的，但“失败根本不是成功”是错误的。

Einstein’s greatest success came in 1919, when Arthur Eddington did the experiment that Freundlich had set out to do, and ascertained that lights in the heavens were all askew during an eclipse, bent by the sun’s dark gravity, just as Einstein had predicted.

爱因斯坦在1919年取得了巨大成功，当时亚瑟·爱丁顿(Arthur Eddington)做了弗罗因德利希之前开始做的实验，他发现，正如爱因斯坦预测的那样，出现日食时，天空中的光线在太阳的暗引力下发生弯曲，出现偏斜。

Asked what he would have done if general relativity had failed, Einstein said, “Then I would have been sorry for the dear Lord. The theory is correct.”

被问及如果广义相对论失败了，他会做什么时，爱因斯坦曾说，“那我会替敬爱的主感到难过。这个理论是正确的。”

And still the champ.

而且直到今天还是最棒的。