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This is a more complicated question that you probably realise. This first point to make is that the speed of light is always locally $c$, that is, if you measure the speed of light at your location you will always get the result $c$. The problem comes when you measure the speed of light at some location distant from you. To measure the speed of light ...

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The following articles may be helpful. This is actually an active scientific topic. http://www.symmetrymagazine.org/breaking/2009/02/19/most-extreme-gamma-ray-blast-also-probes-quantum-gravity http://www.sciencemag.org/content/323/5922/1688.abstract http://www.sciencemag.org/content/early/2013/11/20/science.1242353.abstract

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There is no experimental evidence on whether light travels slower in a gravity field. Some quantum gravity theories require light to be slower in an intensive gravitational field while others not so. So, it is to be determined by experiments or astronomical observations. Light travels in glass as fast as in vacuum. Because microscopically, glass is nothing ...

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You have separate Fresnel equations for s- and p-polarized light. The two polarizations reflect/refract separately. You can reconstitute them on the other side to recover the new polarization vector if you want.

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I have since found this pdf from CVI Melles Griot giving a temperature coefficient of 0.016 nm/°C at 400 nm, increasing to 0.027 nm/°C at 820 nm. This will vary between coating types but it is enough to get started.

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I suppose it depends on application. For example, broadband dielectric mirrors sold by ThorLabs do not specify their temperature-dependence for the obvious reason of redshift magnitude you specified. Even narrowband dielectrics and laser line mirrors don't usually specify this. However, other devices such as crystal optics for wavemixing can strongly depend ...

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I will turn my comment into an answer, because the question in the header: Do photons age? is very anthropomorphic , and physics is a discipline that discourages interpreting data by use of the anthropic principle. The photon is an elementary particle. Aging is not a verb to be used with elementary particles in general because a) they have no ...

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Photons don't have a rest frame, since in all inertial frames they must go at the speed of light. So the following statement: By that logic, photons don't age in a vacuum state as, to us, the time stops for them. is meaningless because one really can't talk about proper time for a photon. However, in a medium, their speed decreases, Nope. The ...

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