When did the red=hot, blue=cold convention first appear? Very likely it preceeded the theory of black body radiation, and it certainly preceeded the technology required to make an object blue hot. Perhaps the proper analogy is that red is the color of fire, and blue is the color of ice. --- Henry Baker <hbaker1@pipeline.com> wrote:
I think that many missed the point of my previous posting.
Red is longer in wavelength than blue, and that will be true across the universe. The "blackbody" radiation equation says that something giving off large amounts of blue color will be hotter than something giving off large amounts of red color.
Note that the defn of "red" & "blue" are independent of the types of sensors that are used to sense the "red" and "blue", so long as they are limited to the passband of the human visual system -- approx 400-750 nm.
Of course, using red & blue still requires an analogy, since a blackbody at 40 F or 110 F do not give off primarily blue and red light, but infrared light of perhaps 13000 nm (?, order of magnitude) wavelength.
Unlike most other things human, using red & blue then isn't entirely an arbitrary choice.
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Yes, I also got caught in Central America by the switch with "H" and "C". I believe that the newer "red" & "blue" labels were supposed to remove this ambiguity, sort of like the Olympic signs that everyone makes fun of.
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My guess is that the meaning of red & blue comes from the effect water has on a Caucasian's skin -- stand in a cold shower and he turns "blue"; stand in a hot shower and he turns "red".
So how come the P.C. police haven't gone after these labels?
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