brennan
Argumentative Brit
Why are there 7 colours in the 'rainbow' (or spectrum if you prefer)?
Cumulative General Science/Technology Quiz
- Thread starter Catharsis
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There aren't - the spectrum is continuous, but human vision evolved in such a way as to pick out certain brackets of wavelengths preferentially. For instance, we can see more subtler shades of Green than Orange. But, just like with musical notes, the 'color' we call Green is just as arbitrary as the note we assign to 440Hz.
brennan
Argumentative Brit
Correct of course, but you need to take the question at face value i'm afraid...
Mise
isle of lucy
When white light moves from one medium into another, it refracts. The angle at which it refracts is proportional to its wavelength. Since white light is made up of many different wavelengths, the refraction angle is different. However, light typically moves from air to another medium (say, glass), and then back out to air. If the glass's edges are parallel to one another (which they typically are), then all wavelengths of light are parallel when they come out anyway, even if they're not parallel when they're inside the glass. So you only see a spectrum when the edges of the medium aren't parallel, e.g. in a prism or a raindrop. The rainbow is made up of 7 colours cos white light's made up of 7 colours (different wavelengths), and the refractive properties of the raindrop allows you to see them apart from one-another.
brennan
Argumentative Brit
hehe you need to take off your scientist cap and put on your historian cap for this one.
Genocidicbunny
Bug squasher
Because Newton said so?
Mise
isle of lucy
cos Richard Of York Gave Battle In Vein?
nonconformist
Miserable
It's thermodynamics, which is quite a big part of forensics.
Well, I thought about that, but I don't think that we do see separate colours in the spectrum. We have three different light-sensitive cells (responsive to 440, 540 and I think 570 nm wavelength), but we use inputs from each to calculate colour range. I don't think that we see six troughs of low light detection in order to distinguish 7 separate colours.
xienwolf
Deity
Hrm, well you said to dislodge your science brain and aim for History. So I would then assume the TRUE question is "Why is the rainbow defined to have 7 colors?"
So I'll venture that it is due to some ancient society only having 7 varieties of commonly usable dye which they could make? If I have to choose a specific society then I'll wager for... Roman?
So I'll venture that it is due to some ancient society only having 7 varieties of commonly usable dye which they could make? If I have to choose a specific society then I'll wager for... Roman?
GoodGame
Red, White, & Blue, baby!
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I'm so intrigued by this that I broke thread rules and googled several links. Apparently this really is a religious reference (torah/talmud), so I'd suggest this question be voided as it's not really scientific in the modern sense (Though it is interesting in an anthropological/religious sense).
brennan
Argumentative Brit
Well I don't know how serious he was but Dutchfire was more or less correct:
When he wasn't blazing the way in what we now consider to be mainstream science Newton also dabbled in Alchemy, and possibly Astrology. He was a very religious man and believed strongly in the significance of the number 7 - there are indeed 7 days in the week, there are also 7 notes in a scale etc. So having started off with just five colours in the spectrum, red, yellow, green, blue and violet; he added two more - orange and indigo, to make it the ideal number 7.
When he wasn't blazing the way in what we now consider to be mainstream science Newton also dabbled in Alchemy, and possibly Astrology. He was a very religious man and believed strongly in the significance of the number 7 - there are indeed 7 days in the week, there are also 7 notes in a scale etc. So having started off with just five colours in the spectrum, red, yellow, green, blue and violet; he added two more - orange and indigo, to make it the ideal number 7.
That's very interesting... is he the one who actually came up with the name Orange? Why didn't he pick something that rhymed with at least one other word? 
Catharsis
catch u on the flip scythe
That's very interesting... is he the one who actually came up with the name Orange? Why didn't he pick something that rhymed with at least one other word?
*klaxons*.
I'm always serious when I'm right, and joking when I'm wrong
I don't have a question right now, so I'll open the floor.
what deficiency in terms of biosynthesis of an essential compound do (most) apes, humans, guinea pigs and bats have in common?
Aramazd
Deity
actually that sound more like birds - the urea cycle is working quite well in all humans surviving birth
you are up 
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