The Beginning of the Universe

By Stephen Hawking

The beginning of the universe had,of course, been discussed for a long time. According to a number of early cosmologies in the Jewish/Christian/Muslim tradition, the universe started at a finite and not very distant time in the past. One argument for such a beginning was the feeling that it was necessary to have a first cause to explain the existence of the universe.

[2] Another argument was put forward by St. Augustine in his book, The City of God. He pointed out that civilization is progressing, and we remember who performed this deed or developed that technique. Thus man, and so also perhaps the universe, could not have been around all that long. For otherwise we would have already progressed more than we have.

诚然，有关宇宙之开端的讨论可谓是由来已久。在犹太教、基督教或伊斯兰教的早期传说中有着若干种宇宙学，根据这类宇宙学，宇宙应始于过去某个有限而并不太遥远的时刻。之所以存在这样一个开端的一个理由是，感觉上必然要有一个造物主来解释宇宙的存在。

[2]另一个论点由圣奥古斯丁在他的《上帝之城》一书中提出。圣奥古斯丁指出，文明的发展是渐进式的，而我们记住了是谁完成了这项业绩，又是谁开发出了那项技术。有鉴于此，人类——因而也许还有宇宙，就不可能已经存在了太长的时间。不然的话，今天人类文明的进展应当比我们现已取得的更为超前。

[3] St. Augustine accepted a date of about 5000 B.C. for the creation of the universe according to the book of Genesis. It is interesting that this is not so far from the end of the last Ice Age, about 10,000 B.C., which is when civilization really began. Aristotle and most of the other Greek philosophers, on the other hand, did not like the idea of a creation because it made too much of divine intervention. They believed, therefore,that the human race and the world around it had existed, and would exist,forever. They had already considered the argument about progress, described earlier, and answered it by saying that there had been periodic floods or other disasters that repeatedly set the human race right back to the beginning of civilization.

[4] When most people believed in an essentially static and unchanging universe, the question of whether or not it had a beginning was really one of metaphysics or theology. One could account for what was observed either way. Either the universe had existed forever, or it was set in motion at some finite time in such a manner as to look as though it had existed forever. But in 1929, Edwin Hubble made the landmark observation that wherever you look, distant stars are moving rapidly away from us. In other words, the universe is expanding.This means that at earlier times objects would have been closer together. In fact, it seemed that there was a time about ten or twenty thousand million years ago when they were all at exactly the same place.

[3]依据《创世记》一书所述，圣奥古斯丁所采用的宇宙创生之时约为公元前5000年。有意思的是，这一时间距最近一次冰河期结束之际不算太远，该冰期约终结于公元前10000年，而那时人类文明已经萌发了。另一方面，亚里士多德和大多数其他希腊哲学家并不喜欢创生的观念，因为这掺入了太多的神授因素。所以，他们认为人类和人类周围的世界在过去和将来都是永恒存在的。他们已经考虑到了前面所提到的关于文明进展的论点，对此他们的辩答是，由于洪水和其他天灾的周期性出现，人类一次又一次地退回到文明的起端。

[4]当大部分人对一个基本上处于静态、无变化的宇宙深信不疑之时，宇宙是否有一个开端的问题，实质上便成了某种玄学或神学问题。人们可以就两条不同的途径来说明所观测到的现象：或者宇宙永恒存在，或者它在某个有限时间内处于运动之中，而运动的方式恰好使宇宙看上去就像是永恒存在一样。但是在1929年，埃德温·哈勃完成了一项划时代的观测，即无论你朝何处看，遥远的恒星都在快速地远离我们而去。换言之，宇宙正在膨胀。这意味着在过去的某个时间，天体应该更紧密地集聚在一起。事实上，似乎在大约100亿或200亿年前的某个时间，所有这些天体都恰好位于相同的位置上。

[5] This discovery finally brought the question of the beginning of the universe into the realm of science.Hubble’s observations suggested that there was a time called the big bang when the universe was infinitesimally small and, therefore, infinitely dense. If there were events earlier than this time,then they could not affect what happens at the present time. Their existence can be ignored because it would have no observational consequences.

[5]这一发现最终把宇宙之开端的问题纳入了科学的范畴。哈勃的观测表明，曾经存在一个称之为大爆炸的时刻，那时宇宙为无限小，因而其密度必为无穷大。如果在这之前还曾出现过一些事件，那么这类事件也不会影响到现在所发生的一切。它们的存在可以忽略而不予考虑，因为它们不会产生任何观测效应。

[6] One may say that time had a beginning at the big bang, in the sense that earlier times simply could not be defined. It should be emphasized that this beginning in time is very different from those that had been considered previously. In an unchanging universe, a beginning in time is something that has to be imposed by some being outside the universe. There is no physical necessity for a beginning. One can imagine that God created the universe at literally any time in the past. On the other hand, if the universe is expanding, there may be physical reasons why there had to be a beginning. One could still believe that God created the universe at the instant of the big bang. He could even have created it at a later time in just such a way as to make it look as though there had been a big bang. But it would be meaningless to suppose that it was created before the big bang. An expanding universe does not preclude a creator, but it does place limits on when He might

have carried out his job.

[6]人们可以说时间有一个起点，即大爆炸瞬刻，这意味着在这之前的时间是完全不可定义的。应该强调的是，时间有起点之说与以前习以为常的观念大不相同。在一个无变化的宇宙中，时间上的起点必然是由来自宇宙之外、某种不为人知的外因所赋予的。对于一个起点来说，并不存在物理学上的必然性。人们可以设想，上帝确实在过去的任意时刻创造出了宇宙。另一方面，如果宇宙正在膨胀，那么也许存在一些物理学上的理由，可用来说明为什么必然有过一个开端。人们仍然可以相信，是上帝在大爆炸瞬间创造出了宇宙。上帝甚至可以在大爆炸后的某个时刻创造出宇宙，不过创造的方式恰好能使宇宙看上去曾经历过一次大爆炸。但是，设定宇宙创生于大爆炸之前是毫无意义的。一个膨胀中的宇宙并不排斥创世主的存在，但它确实对创世主有可能完成其使命的时间划定了范围。