Rainbow

From: Klaus Ole Kristiansen <klaus_at_diku.dk>
Date: Thu, 17 Aug 1995 09:10:10 +0200


Someone asked why the people of Glorantha have to see seven colors in the rainbow. There is no reason at all why they should.

The Lunars, with their obsession with the number seven, may consider the rainbow seven colored. With the westerners it is most likely three, for similar reasons. Other cultures are anybody's guess. How many colors do rainbows have in real world China? Some might not count at all.

The seven colors are not ancient in our culture. At the end of Paradise Lost, Milton has God show Adam part of the future. He shows him the flood, and the three colored arc he will set in the sky afterwards as a sign that he won't do it again. I am not well read in old litterature, but Milton leaves a strong impression that three was the accepted number in his time.

I don't know for sure, but I think it a safe bet that the seven colors of the rainbow come from the seven colors of the spectrum, which again come from Newton's obsession with the number seven. Newton was not the first of the rationalists, but the last of the magicians, to quote Hollingdale.

The rainbow does not consist of distinct bands of color but of one continuum. How many colors you name is a matter of tradition. It also has to do with color names. Once the red and yellow bands blended into a reddish yellow where they met. Now, when "orange" has been established as a color, there is an orange band. Some cultures consider blue and green one color. (This has nothing to do with rainbows, but it will never cease to amaze me that to the English speaking word, pink is a seperate color rather than a shade of red.)

Even so, you have to add the non-standard color "indigo" to get seven. I have never seen two distinct blue bands in the rainbow.

As for the deep color inside the violet, you might try this party game some time: put a sheet of white paper on a wall. Use a grid or prism to project a spectrum on it. Now have each participant mark the edges of the visible spectrum with a pencil. The border between visible and invisible light is a very individual thing.

Klaus O K


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