三本有趣的科普書

1.《The Joy Of X》

第25章—— 最孤獨的數

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.

所謂Twin Primes就是兩個緊鄰的質數,比如11和13,17和19。因爲質數本身的分佈就是越來越稀疏,想發現這樣的Twin Primes就更加困難。上面摘錄的這句原文說的就是,目前已知最大的兩個Twin Primes有超過10萬位的數字組成。後半句則更加詩意,說兩者像一對情侶,在數軸上那個黑暗的位置上相互依偎。靠得很近,卻無法觸碰到對方,因爲它們之間還有一個數字間隔着。也就是前文說到的:

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

從沒想過自己會讀完這本五百多頁的書,即便是科普書,能讓讀者耐心讀完也需要很深的寫作功力。下面要引用這句就是全書令我印象最深的一句話:

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證明了恆星的死亡並不是核合成過程的終止。恆星最終爆炸,各種元素漫天飛舞,與其他太空中的“垃圾”一起漂浮。最終它們被某處吸引,混合在一起,不斷壓縮形成了下一代恆星。我們的太陽被認爲已經是第三代恆星了。

我們生存的時代,那些恆星已經死去,十億甚至幾十億年。但我們血液裏的鐵,骨骼裏的鈣,每次呼吸進肺中的氧氣,無不來自它們,來自遠在地球誕生之前,在宇宙這個大熔爐裏“生老病死”的其他恆星。我們就是它們曾經在這個宇宙中存在過的證明。

3.《Reality is Not What It Seems》

恰逢最近一則新聞,說加拿大一天文臺收到15億光年外的連續信號,讓我不禁想起了這本書中關於“現在”這個概念的講述:

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.

光年相信大家都瞭解,光在空間中傳播一年的距離。可我們可能對它背後帶來的影響還沒有意識到,對像“現在”、“當下”這些習以爲然的概念依然未察覺到任何問題。

前面摘錄的這句話說的就是:時間上“現在”這個概念就像空間上地球是平的一樣,都是盲目人類的幻覺。如果我們的大腦足夠靈敏,能夠感受到納秒級別的時間差異,那麼我們可能永遠都不會有“現在”這個概念。我們打電話給朋友時,不會再問“你現在在做什麼”。

但我們的大腦就是如此“遲鈍”,不過沒有關係,在宇宙的尺度上,我們同樣可以被震撼。15億光年的信號,即便是“人爲”,背後的文明也不復存在。當你被哈勃望遠鏡拍到的7000光年外“創世之柱”(Pillar of Creation)的照片震撼時,你卻已經無法觸及到,因爲在1000年前它已經消散。所以愛因斯坦提出了Spacetime概念,提出了空間與時間密不可分的關係。時間因空間的距離和空間的扭曲而改變。

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