“
Once a photon hits Earth's atmosphere, it slows down slightly.”
https://www.newscientist.com/lastwo...-photon-know-to-travel-at-the-speed-of-light/
https://en.wikipedia.org/wiki/Scattering/
The photon does not slow down. Photons only travel at C.
It is the light wave that slows down due to scattering
(photons take a longer path from point A to point B … due to collisions). This is called refraction.
“
No particle with mass can reach the vacuum speed of light,
but if it's very light and has a lot of energy, it can get very close ...
The superfast neutrino detected in 2016 would have 33 9s”
Yet many people (including some scientists) still believe
that as a particle approaches C, its mass approaches infinity …
observations (like the one above) aren’t on their side.