Why do most rainbows look stripy?

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JimC
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Re: Why do most rainbows look stripy?

Post by JimC » Mon Dec 16, 2013 7:35 pm

There are certainly some weird things about the way we detect colour using red, green and blue cones. For example, the way we detect yellow light. The point where the sensitivity graphs of red and green cross is pretty well the wavelength at the centre of the yellow band. If you shine pure yellow light into the eye, at (or centred in) that wavelength, it equally stimulates the red and green cones, while not giving the blue cones the slightest tickle. So, if our brain receives the message that green and red are equally stimulated, with no blue, it registers as yellow.

We can "fool" the brain using this. If you shine 2 rays, say from a LED sources, one of pure green and the other red, equal intensities, we experience exactly the same qualia that would be generated by a beam of pure yellow. I use this to emphasise to my students that our vision sense is very different from a scientific instrument like a spectrophotometer...
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MiM
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Re: Why do most rainbows look stripy?

Post by MiM » Mon Dec 16, 2013 7:41 pm

Of course, that's the technique used by all modern screens and projectors.
The first principle is that you must not fool yourself, and you are the easiest person to fool - Richard Feynman

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