Re: [OT] still blue
On 2022-07-25, Nicolas George <george@nsup.org> wrote:
>
> uniform in frequency and reciprocally). The best we can do is know
> that our eye evolved for the light of the Sun, and therefore is
> optimized for its light, and white is anything that looks like the
> Plank spectrum at 5800 K, although 6500 K usually appears somewhat
> whiter.
The peak brightness of the solar spectrum is in the green when plotted in
wavelength units. It peaks in the near-infrared when plotted in frequency
units. Therefore the oft-quoted notion that evolution led to an optimized eye
whose sensitivity peaks where there is most available sunlight is misleading
and erroneous. The confusion arises when density distribution functions like
the spectral radiance are compared with ordinary functions like the sensitivity
of the eye. Spectral radiance functions, excepting very narrow ones, can change
peak positions greatly when transformed from wavelength to frequency units, but
sensitivity functions do not. Expressing the spectral radiance in terms of
photons per second, rather than power, also causes a change in the shape and
peak of the distribution, even keeping the choice of bandwidth units fixed. The
confusion arising from comparing simple functions to distribution functions
occurs in many parts of the scientific and engineering literature aside from
vision, and some examples are given. The eye does not appear to be optimized
for detection of the available sunlight, including the surprisingly large
amount of infrared radiation in the environment. The color sensitivity of the
eye is discussed in terms of the spectral properties and the photo and chemical
stability of available biological materials. It is likely that we are viewing
the world with a souvenir of the human evolutionary voyage. © 1999 American
Association of Physics Teachers
https://www.researchgate.net/publication/236003842_Some_paradoxes_errors_and_resolutions_concerning_the_spectral_optimization_of_human_vision
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