万物简史 第20期:如何营造一个宇宙(12)

 　　I should say that everything is just right so far. In the long term, gravity may turn out to be a little too strong, and one day it may halt the expansion of the universe and bring it collapsing¹ in upon itself, till it crushes itself down into another singularity, possibly to start the whole process over again.

　　我要说，到目前为止，一切都恰到好处。从长远来说，引力也许会变得稍强一点；有朝一日，它可能阻止宇宙膨胀，让自己将自己压瘪，最后坍缩成又一个奇点，整个过程很可能重新开始。

　　On the other hand it may be too weak and the universe will keep racing² away forever until everything is so far apart that there is no chance of material interactions, so that the universe becomes a place that is inert³ and dead, but very roomy. The third option is that gravity is just right—"critical density⁴" is the cosmologists' term for it—and that it will hold the universe together at just the right dimensions to allow things to go on indefinitely. Cosmologists in their lighter⁵ moments sometimes call this the Goldilocks effect—that everything is just right. (For the record, these three possible universes are known respectively as closed, open, and flat.)另一方面，引力也许会变得过弱，那样的话，宇宙会永远地膨胀，直到一切都互相远离，不再可能发生实质性的相互作用，于是宇宙就成为一个非常空旷呆滞而又没有生命的地方。第三种可能是，引力恰如其分--就是宇宙学所谓的"临界密度"--它把宇宙控制在一个恰当的范围，使事物永远继续下去。宇宙学家有时轻浮地把这称之为"金发姑娘效应"--一切都处于恰如其分的状态。（需要说明的是，这三种可能出现的宇宙分别叫做封闭式宇宙、开放式宇宙和扁平式宇宙。）Now the question that has occurred to all of us at some point is: what would happen if you traveled out to the edge of the universe and, as it were, put your head through the curtains? Where would your head be if it were no longer in the universe? What would you find beyond?

　　大家迟早会想到一个问题，那就是，假设你来到宇宙边缘，把头伸出帘幕，那会发生什么？你的头会在什么地方(要是它不再是在宇宙里的话)？你会看到对面是什么？

　　The answer, disappointingly, is that you can never get to the edge of the universe. That's not because it would take too long to get there—though of course it would—but because even if you traveled outward and outward in a straight line, indefinitely and pugnaciously⁶, you would never arrive at an outer boundary. Instead, you would come back to where you began (at which point, presumably, you would rather lose heart in the exercise and give up).

　　回答是令人失望的：你永远也到不了宇宙的边缘。倒不是因为去那里要花很长时间--虽然没错儿，的确要花很长时间--而是因为，即使你沿着一条直线往外走，不停地坚持往外走，你也永远到不了宇宙的边缘。恰恰相反，你会回到起始的地方（到了这种地步，你很可能会灰心丧气，放弃这种努力）。

　　The reason for this is that the universe bends, in a way we can't adequately imagine, in conformance with Einstein's theory of relativity (which we will get to in due course). For the moment it is enough to know that we are not adrift in some large, ever-expanding bubble.

　　其原因是，按照爱因斯坦的相对论（我们届时将会讲到），宇宙是弯曲的。至于怎么弯曲，我们也不大能想像出来。眼下，你只要知道，我们并不是在一个不断膨胀的大气泡里飘浮，这就足够了。

　　Rather, space curves, in a way that allows it to be boundless⁷ but finite. Space cannot even properly be said to be expanding because, as the physicist⁸ and Nobel laureate Steven Weinberg notes, "solar systems and galaxies⁹ are not expanding, and space itself is not expanding." Rather, the galaxies are rushing apart. It is all something of a challenge to intuition. Or as the biologist J. B. S. Haldane once famously observed: "The universe is not only queerer than we suppose; it is queerer than we can suppose."确切点说，空间是弯曲的，恰好使其无限而又有限。恰当地说，甚至不能说空间在不断膨胀，这是因为，正如诺贝尔奖获得者、物理学家史蒂文·温伯格指出的："太阳系和星系不在膨胀，空间本身也不在膨胀。"倒是星系在飞速彼此远离。这对直觉都是一种挑战。生物学家J.B.S.霍尔丹有一句名言："宇宙不仅比我们想像的要古怪，而且比我们可能想像的还要古怪。"

1 collapsing   

压扁[平]，毁坏，断裂

参考例句：

• Rescuers used props to stop the roof of the tunnel collapsing. 救援人员用支柱防止隧道顶塌陷。
• The rocks were folded by collapsing into the center of the trough. 岩石由于坍陷进入凹槽的中心而发生褶皱。

2 racing   

n.竞赛，赛马；adj.竞赛用的，赛马用的

参考例句：

• I was watching the racing on television last night.昨晚我在电视上看赛马。
• The two racing drivers fenced for a chance to gain the lead.两个赛车手伺机竞相领先。

3 inert   

adj.无活动能力的，惰性的；迟钝的

参考例句：

• Inert gas studies are providing valuable information about other planets,too.对惰性气体的研究，也提供了有关其它行星的有价值的资料。
• Elemental nitrogen is a very unreactive and inert material.元素氮是一个十分不活跃的惰性物质。

4 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

5 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

6 pugnaciously   

参考例句：

7 boundless   

adj.无限的；无边无际的；巨大的

参考例句：

• The boundless woods were sleeping in the deep repose of nature.无边无际的森林在大自然静寂的怀抱中酣睡着。
• His gratitude and devotion to the Party was boundless.他对党无限感激、无限忠诚。

8 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

9 galaxies   

星系( galaxy的名词复数 )； 银河系； 一群（杰出或著名的人物）

参考例句：

• Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
• We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。