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.

誠然，有關(guān)宇宙之開端的討論可謂是由來已久。在猶太教、基督教或伊斯蘭教的早期傳說中有著若干種宇宙學(xué)，根據(jù)這類宇宙學(xué)，宇宙應(yīng)始于過去某個有限而并不太遙遠的時刻。之所以存在這樣一個開端的一個理由是，感覺上必然要有一個造物主來解釋宇宙的存在。

[2]另一個論點由圣奧古斯丁在他的《上帝之城》一書中提出。圣奧古斯丁指出，文明的發(fā)展是漸進式的，而我們記住了是誰完成了這項業(yè)績，又是誰開發(fā)出了那項技術(shù)。有鑒于此，人類——因而也許還有宇宙，就不可能已經(jīng)存在了太長的時間。不然的話，今天人類文明的進展應(yīng)當比我們現(xiàn)已取得的更為超前。

[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]依據(jù)《創(chuàng)世記》一書所述，圣奧古斯丁所采用的宇宙創(chuàng)生之時約為公元前5000年。有意思的是，這一時間距最近一次冰河期結(jié)束之際不算太遠，該冰期約終結(jié)于公元前10000年，而那時人類文明已經(jīng)萌發(fā)了。另一方面，亞里士多德和大多數(shù)其他希臘哲學(xué)家并不喜歡創(chuàng)生的觀念，因為這摻入了太多的神授因素。所以，他們認為人類和人類周圍的世界在過去和將來都是永恒存在的。他們已經(jīng)考慮到了前面所提到的關(guān)于文明進展的論點，對此他們的辯答是，由于洪水和其他天災(zāi)的周期性出現(xiàn)，人類一次又一次地退回到文明的起端。

[4]當大部分人對一個基本上處于靜態(tài)、無變化的宇宙深信不疑之時，宇宙是否有一個開端的問題，實質(zhì)上便成了某種玄學(xué)或神學(xué)問題。人們可以就兩條不同的途徑來說明所觀測到的現(xiàn)象：或者宇宙永恒存在，或者它在某個有限時間內(nèi)處于運動之中，而運動的方式恰好使宇宙看上去就像是永恒存在一樣。但是在1929年，埃德溫·哈勃完成了一項劃時代的觀測，即無論你朝何處看，遙遠的恒星都在快速地遠離我們而去。換言之，宇宙正在膨脹。這意味著在過去的某個時間，天體應(yīng)該更緊密地集聚在一起。事實上，似乎在大約100億或200億年前的某個時間，所有這些天體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]這一發(fā)現(xiàn)最終把宇宙之開端的問題納入了科學(xué)的范疇。哈勃的觀測表明，曾經(jīng)存在一個稱之為大爆炸的時刻，那時宇宙為無限小，因而其密度必為無窮大。如果在這之前還曾出現(xiàn)過一些事件，那么這類事件也不會影響到現(xiàn)在所發(fā)生的一切。它們的存在可以忽略而不予考慮，因為它們不會產(chǎn)生任何觀測效應(yīng)。

[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]人們可以說時間有一個起點，即大爆炸瞬刻，這意味著在這之前的時間是完全不可定義的。應(yīng)該強調(diào)的是，時間有起點之說與以前習(xí)以為常的觀念大不相同。在一個無變化的宇宙中，時間上的起點必然是由來自宇宙之外、某種不為人知的外因所賦予的。對于一個起點來說，并不存在物理學(xué)上的必然性。人們可以設(shè)想，上帝確實在過去的任意時刻創(chuàng)造出了宇宙。另一方面，如果宇宙正在膨脹，那么也許存在一些物理學(xué)上的理由，可用來說明為什么必然有過一個開端。人們?nèi)匀豢梢韵嘈?，是上帝在大爆炸瞬間創(chuàng)造出了宇宙。上帝甚至可以在大爆炸后的某個時刻創(chuàng)造出宇宙，不過創(chuàng)造的方式恰好能使宇宙看上去曾經(jīng)歷過一次大爆炸。但是，設(shè)定宇宙創(chuàng)生于大爆炸之前是毫無意義的。一個膨脹中的宇宙并不排斥創(chuàng)世主的存在，但它確實對創(chuàng)世主有可能完成其使命的時間劃定了范圍。