万物简史 第176期:爱因斯坦的宇宙(19)

 　　The most challenging and nonintuitive of all the concepts in the general theory of relativity is the idea that time is part of space. Our instinct is to regard time as eternal, absolute, immutable—nothing can disturb its steady tick. In fact, according to Einstein, time is variable and ever changing. It even has shape. It is bound up—"inextricably interconnected,"in Stephen Hawking’s expression—with the three dimensions of space in a curious dimension known as spacetime.

　　在“广义相对论”的众多概念中，最具挑战性的，最直觉不到的，在于时间是空间的组成部分这个概念。我们本能地把时间看做是永恒的，绝对的，不可改变的，相信什么也干扰不了它的坚定步伐。事实上，爱因斯坦认为，时间是可以更改的，不断变化的。时间甚至还有形状。一份时间与三份空间结合在一起——用斯蒂芬·霍金的话来说是“无法解脱地交织在一起”——不可思议地形成一份“时空”。

　　对相对论的理解图

　　Spacetime is usually explained by asking you to imagine something flat but pliant—amattress, say, or a sheet of stretched rubber—on which is resting a heavy round object, such as an iron ball. The weight of the iron ball causes the material on which it is sitting to stretch and sag¹ slightly. This is roughly analogous² to the effect that a massive object such as the Sun(the iron ball) has on spacetime (the material): it stretches and curves and warps³ it. Now if you roll a smaller ball across the sheet, it tries to go in a straight line as required by Newton’s laws of motion, but as it nears the massive object and the slope of the sagging⁴ fabric⁵, it rolls downward, ineluctably drawn⁶ to the more massive object. This is gravity—a product of the bending of spacetime.

　　通常，时空是这样解释的：请你想像一样平坦而又柔韧的东西——比如一块地毯或一块伸直的橡皮垫子——上面放个又重又圆的物体，比如铁球。铁球的重量使得下面的底垫稍稍伸展和下陷。这大致类似于太阳这样的庞然大物（铁球）对于时空（底垫）的作用：铁球使底垫伸展、弯曲、翘起。现在，要是你让一个较小的球从底垫上滚过去，它试图做直线运动，就像牛顿运动定律要求的那样。然而，当它接近大球以及底垫下陷部分的时候，它就滚向低处，不可避免地被大球吸了过去。这就是引力——时空弯曲的一种产物。

1 sag   

v.下垂，下跌，消沉；n.下垂，下跌，凹陷，[航海]随风漂流

参考例句：

• The shelf was beginning to sag beneath the weight of the books upon it.书架在书的重压下渐渐下弯。
• We need to do something about the sag.我们须把下沉的地方修整一下。

2 analogous   

adj.相似的；类似的

参考例句：

• The two situations are roughly analogous.两种情況大致相似。
• The company is in a position closely analogous to that of its main rival.该公司与主要竞争对手的处境极为相似。

3 warps   

n.弯曲( warp的名词复数 )；歪斜；经线；经纱v.弄弯，变歪( warp的第三人称单数 )；使（行为等）不合情理，使乖戾，

参考例句：

• This wood warps easily in damp conditions. 这种木料受潮容易变形。 来自《简明英汉词典》
• Matt Lauer: Renewable biofuels. Park Ranger Rick Marshall Close. Time warps. 马特·劳尔：“可再生生物燃料。”瑞克：“不说了，时间都扭曲了。” 来自互联网

4 sagging   

下垂[沉，陷]，松垂，垂度

参考例句：

• The morale of the enemy troops is continuously sagging. 敌军的士气不断低落。
• We are sagging south. 我们的船正离开航线向南漂流。

5 fabric   

n.织物，织品，布；构造，结构，组织

参考例句：

• The fabric will spot easily.这种织品很容易玷污。
• I don't like the pattern on the fabric.我不喜欢那块布料上的图案。

6 drawn   

v.拖，拉，拔出；adj.憔悴的，紧张的

参考例句：

• All the characters in the story are drawn from life.故事中的所有人物都取材于生活。
• Her gaze was drawn irresistibly to the scene outside.她的目光禁不住被外面的风景所吸引。