01.光与色

Light and Color

色彩与光密不可分。在完全黑暗的地方，我们看不到颜色，红色的苹果，黄色的香蕉都成了隐形物体。如果没有物体存在，我们也看不到颜色，因此，呈现颜色的物体是必要的。人们对于颜色的感觉取决于大脑对由眼睛传来的信号的解析。所以，可见光、物体和人视觉系统（眼、视神经、脑），三者缺一不可，称为视觉三要素。

揭开光色之谜的是英国科学家牛顿。1666年，牛顿进行了著名的色散实验。在一间漆黑的房间中，他只在窗户上开了一条窄缝，让太阳光通过一个三角形柱体的玻璃三棱镜射入房间。结果，令人意外的奇迹出现了：在对面墙上出现了一条七色光带，而不是一片白光，这七色按红、橙、黄、绿、蓝、靛、紫的顺序一色紧挨一色地排列着，极像雨过天晴时出现的彩虹。同时，七色光带再通过一个三棱镜还能还原成白光。这条七色光带就是光谱。这个实验被称为“物理学最美实验。”

这个现象说明，我们看到的太阳光、日光灯等光源是复合光，是由很多种颜色的单色光组合而成的。在牛顿之后，大量的科学研究成果进一步告诉我们，色彩是以色光为主体的客观存在，对于人则是一种视象感觉，产生这种感觉基于三种因素：一是光；二是物体对光的反射；三是人的视觉器官——眼。即不同波长的可见光投射到物体上，有一部分波长的光被吸收，另一部分波长的光被反射出来刺激人的眼睛，经过视神经传递到大脑，形成对物体的色彩信息，即人的色彩感觉。物体之所以呈现不同的颜色，根本原因就是物体对光具有选择性吸收、反射、透过的特性。

物理学最美实验：牛顿光色散
没有光，颜色就无从谈起。人们对于光的认知还要追溯到1666年牛顿做的一个著名实验。这场实验中，牛顿让阳光透过三棱镜使其分解为七色彩带。
Physics—the most beautiful experiment in physics—dispersion experiment carried out by Newton.Without light，there is no way to tell the colors.People's understanding of light can be traced back to a famous experiment carried out by Newton in 1666.In this experiment，Newton broke sunlight into seven-color beam through a glass prism.

视觉三要素
眼睛把信号传递给大脑，大脑经过信息处理才得到颜色，这其中既有客观性，又有主观性；既有生理性现象，又有心理性现象。所以涉及到物理学、生物学、心理学等不同的学科。
Three elements of vision
The eye sends signals to the brain，which processes the information to get the color.This is a both physiological and psychological phenomenon.It is both objective and subjective，so it involves different disciplines such as physics，biology，and psychology.

There exist close connections between colors and light.In a place of total darkness,we can see no color.For instance,red apples and yellow bananas become invisible.

Without substances,we cannot see colors,either.Therefore,objects are necessary to display colors.People's feeling about colors depends on their brains' analysis of signals transmitted from eyes.So visible light,objects and human visual system (eye,optic nerve and brain) are indispensable,known as the three elements of vision.

It was Issac Newton,a British scientist,who solved the mystery of colors of light.In 1666,Newton carried out the famous dispersion experiment.He shut a room into darkness,leaving only a slit in the window to allow sunlight to come in and pass through a glass prism.As a result,an unexpected miracle appeared:on the opposite wall,there was a band of light composed of seven colors,instead of an expansion of white light.The seven colors were arranged in the order of red,orange,yellow,green,blue,indigo and purple,which was very similar to the rainbow that appears in the sun after rain.At the same time,if the seven color beam passes through another prism,it can be reduced to white light.This seven color band is spectrum.The experiment is called the most beautiful experiment in physics.

This phenomenon shows that the compound light emitted by the sun,fluorescent lamp and other light sources is composed of monochromatic light of many colors.After Newton,a large amount of scientific research further tells us that color is the objective existence of color light as the main body,and for people,it is a kind of visual sense,which is based on three factors:light,the reflection of objects to light and human's visual organ,eyes.That is to say,the visible light of different wavelengths is projected on the object,part of which is absorbed,and the other part is reflected to stimulate the human eye and is transmitted to the brain through the optic nerve,forming the color information of the object,that is,human sense of colors.Basically,objects show different colors because of the characteristic of selective absorption,reflection and transmission of light.