光的简史-到目前为止

　　光的简史-到目前为止

　　引言和背景

　　上帝说，要有光，就有了光。神看见光，就好了。上帝把光暗分开了”（创1:3-4，ASV）。我敢肯定，我们大多数人都很熟悉《创世纪》中的这些开场白，不管你是否相信它们是真的，事实上，在我们这个世界上，我们现在既有黑暗也有光明。但是什么是光，它来自哪里，它是如何产生的，它的未来是什么样子的？

　　这些都是很好的问题，但我不打算在本文中回答所有这些问题，但是，我想给你们介绍一个从大约140亿年前到今天的光的简史。为什么140亿年前？因为我们知道，这是关于宇宙感谢美国宇航局的威尔金森微波各向异性探测器（简称WMAP）年龄。它被设计成精确地绘制宇宙地图，探测来自最遥远源头的微波——大爆炸的冷却火球。我们的太阳系包括太阳和地球，比宇宙本身要年轻得多，大约只有45亿年。因此，地球上光的主要来源来自我们自己的太阳。现在，大约40亿年前，我们的月亮形成了。没有人确切知道这是如何发生的，尽管四个主要假设是：融合、俘获、共同形成和巨大冲击。［关于这些假设的进一步信息，请参见维基百科］。尽管如此，不管月球是如何形成的，它在夜间给我们提供了一个额外的光源，把太阳反射到地球表面的光子反射回来。

　　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.”