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Comment by fsh

1 day ago

Any interaction between light and matter can be modeled as absorption and re-emission (stimulated or spontaneous) of photons. In this picture, there is not much difference between a photon traveling through the sun or through a piece of glass, and the analog makes physical sense. Since photons are massless elementary particles, they are indistinguishable and their number is not conserved. The notion of "the same photon" is questionable in any case.

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fsh

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gosub100  3 hours ago

I agree that photons cannot be distinguished, but how do you reconcile the following:

- photons travel at the speed of light in a vacuum

- it takes 90k years (or whatever) for a photon to travel from the sun's core to your retina?

Ok, the core of the sun is not a vacuum, quite the opposite, but the path is fraught with being continuously absorbed and emitted. It's not one photon travelling at a few km/hr is it?

And I don't think photons are reflected in hydrogen, although I have no proof. I just thought reflection was done with things like flat surfaces or mirrors.

This is why I said "not the same photon", but I admit I have only YouTube-spectator level knowledge