三本有趣的科普书

Posted 2022-12-04 cdai

1.《The Joy Of X》

第25章—— 最孤独的数

Computers have found twin primes at unbelievably remote parts of the number line. The largest known pair consists of two numbers with 100355 decimal digits each, snuggling in the darkness.

所谓Twin Primes就是两个紧邻的质数，比如11和13，17和19。因为质数本身的分布就是越来越稀疏，想发现这样的Twin Primes就更加困难。上面摘录的这句原文说的就是，目前已知最大的两个Twin Primes有超过10万位的数字组成。后半句则更加诗意，说两者像一对情侣，在数轴上那个黑暗的位置上相互依偎。靠得很近，却无法触碰到对方，因为它们之间还有一个数字间隔着。也就是前文说到的：

Mattie thought that he and Alice were like that, twin primes, alone and lost, close but not close enough to really touch each other.

2.《Big Bang》

第五部分——The Paradigm Shift

从没想过自己会读完这本五百多页的书，即便是科普书，能让读者耐心读完也需要很深的写作功力。下面要引用这句就是全书令我印象最深的一句话：

One of the most important outcomes of Hoyle’s research was that the death of a star did not mark the end of the nucleosynthesis process. As a star implodes it sends out massive shock waves, which leads to an explosion, sending atoms flying out across the universe. … This stellar debris mixes with whatever else might be floating in the cosmos, including the atoms from other dead stars, eventually condensing to form completely new stars… It is thought that our own Sun is probably a third-generation star.
… In order that we might live, stars in their billions, tens of billions, hundreds of billions even, have died. The iron in our blood, the calcium in our bones, the oxygen that fills our lungs each time we take a breath - all were cooked in the furnaces of the stars which expired long before the Earth were born.

Hoyle研究的重要成果就是证明了恒星的死亡并不是核合成过程的终止。恒星最终爆炸，各种元素漫天飞舞，与其他太空中的“垃圾”一起漂浮。最终它们被某处吸引，混合在一起，不断压缩形成了下一代恒星。我们的太阳被认为已经是第三代恒星了。

我们生存的时代，那些恒星已经死去，十亿甚至几十亿年。但我们血液里的铁，骨骼里的钙，每次呼吸进肺中的氧气，无不来自它们，来自远在地球诞生之前，在宇宙这个大熔炉里“生老病死”的其他恒星。我们就是它们曾经在这个宇宙中存在过的证明。

3.《Reality is Not What It Seems》

恰逢最近一则新闻，说加拿大一天文台收到15亿光年外的连续信号，让我不禁想起了这本书中关于“现在”这个概念的讲述：

Had our brain and our senses been more precise, had we easily perceived time in nanoseconds, we would never have made up the idea of a “present” extending everywhere… We would have realized that saying “here and now” makes sense, but that saying “now” to designate events “happening now” throughout the universe makes no sense.

光年相信大家都了解，光在空间中传播一年的距离。可我们可能对它背后带来的影响还没有意识到，对像“现在”、“当下”这些习以为然的概念依然未察觉到任何问题。

前面摘录的这句话说的就是：时间上“现在”这个概念就像空间上地球是平的一样，都是盲目人类的幻觉。如果我们的大脑足够灵敏，能够感受到纳秒级别的时间差异，那么我们可能永远都不会有“现在”这个概念。我们打电话给朋友时，不会再问“你现在在做什么”。

但我们的大脑就是如此“迟钝”，不过没有关系，在宇宙的尺度上，我们同样可以被震撼。15亿光年的信号，即便是“人为”，背后的文明也不复存在。当你被哈勃望远镜拍到的7000光年外“创世之柱”（Pillar of Creation）的照片震撼时，你却已经无法触及到，因为在1000年前它已经消散。所以爱因斯坦提出了Spacetime概念，提出了空间与时间密不可分的关系。时间因空间的距离和空间的扭曲而改变。