Thursday, September 22, 2005

Light question

We see a tree because light comes from the tree and enters our eye.
But why do we see a tree when all we get is light coming from the tree?
What information about the tree does the light contain?
It can only be colour or brightness or both – nothing else.
The colour of light is the same thing as the frequency of the waves of light.
The brightness of the light is the amplitude of the waves of light.
We are told that waves superimpose and that light waves behave in the same way as other waves (see diffraction of light).
Given that the tree is over there and I am here and there are rays of light coming from the tree to my eye made up of light at frequencies and amplitudes corresponding to the colours and brightness of the various parts of the tree.
My question is how does light preserve that information about the tree when in the intervening space between me and the tree there is light of all frequencies and amplitudes passing in all directions and superimposing upon my ‘tree light’.
I would have thought that this would destroy the original information completely by changing the wave.
I am missing something which is pretty obvious I am sure, as nobody else seems to need to raise this question. Can somebody enlighten me?

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