Scatter

So light can be modelled as a wave with properties that vary, including wavelength and frequency. They differ in no other way whatsoever. Our eyes and brain work to 'convert' these waves into colours that depend entirely on their wavelength. Also, light is only a very small section of the whole electro-magnetic spectrum! Hence, our brains are a little deceiving when it comes to the nature of light.

The sky is blue because it has a shorter wavelength, and it can pass through the molecules of the atmosphere without getting scattered. In theory this could change. If the atmosphere became much thinner, more wavelengths of light would be allowed through. This may make the sky shift towards a green colour.

Remember what I said at the beginning, apart from different wavelengths and frequencies, every electro-magnetic wave is pretty much the same thing! Our brains have evolved to use a certain portion of the spectrum - a section that our Sun produces a lot of. It is our brains that decide which wavelength is red and which is blue!

Just as other animals have evolved to hear other frequencies of sound, they may well have brains that convert wavelengths of light into different colours. In addition, they could be able to detect and process wavelengths that we can't see. For example, they could see some of the infra-red waves, and hence they would be able to see heat!

It is incredibly unlikely, but in theory our brains could change in some way to 'see' wavelengths of light differently. We could evolve to see other wavelengths, or the colours we see could change.

I hope this helps!

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