# OFFTOPIC: physics question

jim bell jdb10987 at yahoo.com
Fri May 17 11:43:08 PDT 2019

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On Friday, May 17, 2019, 10:55:25 AM PDT, \0xDynamite <dreamingforward at gmail.com> wrote:

>I think you answered part of my question, which was partly didactic to
force science to get more rigor in its explanation.  I think I will
have to content myself with this because I know that rainbows and the
sky being blue will NEVER be explainable by science.
Mark

No, the reason the sky is blue was explained long ago.  It's called "Rayleigh scattering".
https://en.wikipedia.org/wiki/Rayleigh_scattering
Rayleigh scattering (pronounced /ˈreɪli/ RAY-lee), named after the nineteenth-century British physicist Lord Rayleigh (John William Strutt),[1] is the predominantly elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. Rayleigh scattering does not change the state of material and is, hence, a parametric process. The particles may be individual atoms or molecules. It can occur when light travels through transparent solids and liquids, and is most prominently seen in gases. Rayleigh scattering results from the electric polarizability of the particles. The oscillating electric field of a light wave acts on the charges within a particle, causing them to move at the same frequency. The particle therefore becomes a small radiating dipole whose radiation we see as scattered light. This radiation is an integral part of the photon and no excitation or deexcitation occurs.
[end of quote]
However, that explaination does not include a reference to what my understanding of Rayleigh scattering entails.  Considered on the scale of the wavelength of the light involved, the density of air varies statistically.  Blue is a shorter wavelenth than red, so statistically that variation in air density is greater.  So, blue is scattered more than red.  Blue sky means that more blue is scattered.
Jim Bell

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