Graduation day.

[hazeii]

A north wind, cold and strong. Biting when squeezed between earth and sky, the autumn sun providing little offset. Fingers and toes growing numb, and as the trail before me turned into the trail behind, the problem expanded to fill my head.

Just how many colours are there in a rainbow?

Comments

[hazeii]

Interesting thought! I wonder if humans can adapt to them (you may know the classic experiment of getting someone to wear inverting glasses for a day or two...the brain eventually learns to flip the image, then when you take the glasses off everything is upside down again). Compound lenses may be a bit beyond the normal homo sap. though (however, lower life forms like lawyers and politicians may be able to pull it off).

As for a rainbow having 7 colours...I can't see that except for the anthropomorphic 'Rats of york go by in velvet' mnemonic. There's just red, green, and blue (plus their overlaps yellow and cyan).

Interestingly, there are 7 possible colours if you consider all possible combinations of red, green and blue...r+g=yellow, r+b=violet, b+g=cyan, r+g+b=white plus the 3 primary colours makes 7. Can't get all those combinations in a rainbow, though.

Thanks to other comments to this post, found a couple of interesting web pages about animals/insects seeing more colours, and a potentially interesting human mutation (see the links on this web page if you're interested, esp. 3rd and 4th items from the bottom).