I blogged about why red+blue = purple: xanthir.com/b4XK0 This bugged the *crap* out of young me, and no one talks about it!
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@tabatkins Doesn't it just come down to that a 3 dimensional space can be spanned by any 3 orthogonal vectors?
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@davidbaron Your vision is not well-described as a 3-vector space.
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Replying to @tabatkins
@tabatkins Why not? Each of our 3 response curves is a vector in the ∞-dimensional vector space of possible response curves.

Jul 28, 2014 · 6:53 PM UTC

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Replying to @davidbaron
@davidbaron They're not independent, is why. They are ordered linearly, so the appearance of a loop is surprising.
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@tabatkins Do you mean overlapping ranges (still independent) or that one response curve changes when another responds?
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Replying to @davidbaron
@davidbaron My article is actually about why red+blue light looks similar to purple light.
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@tabatkins Right, and I think that any 3-D vector space is spanned by any bases is a simpler explanation for that.