光的簡史-到目前為止

　　引言和背景

　　上帝說，要有光，就有了光。神看見光，就好了。上帝把光暗分開了”（創1:3-4，ASV）。我敢肯定，我們大多數人都很熟悉《創世紀》中的這些開場白，不管你是否相信它們是真的，事實上，在我們這個世界上，我們現在既有黑暗也有光明。但是什么是光，它來自哪里，它是如何產生的，它的未來是什么樣子的？

　　這些都是很好的問題，但我不打算在本文中回答所有這些問題，但是，我想給你們介紹一個從大約140億年前到今天的光的簡史。為什么140億年前？因為我們知道，這是關于宇宙感謝美國宇航局的威爾金森微波各向異性探測器（簡稱WMAP）年齡。它被設計成精確地繪制宇宙地圖，探測來自最遙遠源頭的微波——大爆炸的冷卻火球。我們的太陽系包括太陽和地球，比宇宙本身要年輕得多，大約只有45億年。因此，地球上光的主要來源來自我們自己的太陽。現在，大約40億年前，我們的月亮形成了。沒有人確切知道這是如何發生的，盡管四個主要假設是：融合、俘獲、共同形成和巨大沖擊。［關于這些假設的進一步信息，請參見維基百科］。盡管如此，不管月球是如何形成的，它在夜間給我們提供了一個額外的光源，把太陽反射到地球表面的光子反射回來。

　　It is generally accepted that man （Homo Erectus） did not appear on earth until about 1，000，000 years ago – a mere blink of an eye in cosmic terms. Clearly， these early humans relied on the sun for their primary lighting since it would not be until much later that any man-made lighting would be available. In fact， many scientists claim that there is incontrovertible evidence which shows that early man created controlled fire about 125，000 years ago. So it was that flaming torches were made and used as the first artificial light sources. However， it was just 17，000 years ago that prehistoric man used lamps for illumination purposes. These lamps were usually made from shells， rocks or horns and were filled with animal or vegetable fats for fuel and used a fiber wick. It would be another 10，000 years later before the fuel for these lamps would consist of olive， nut， sesame or fish oils. These lamps would go through many modifications in materials during the course of next 5，000 years. Then， around 500 B.C.， Pythagoras put forth the ‘Particle’ theory of light. This assumed that every visible object emits a steady stream of particles that bombard the eye. He further suggested that “light consists of rays that， acting like feelers， travel in straight lines from the eye to the object， and the sensation of sight is obtained when these rays touch the object.”