Light speed naivety?

  • Thread starter berty
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  • #1
Light speed naivety??

The speed of light - c is a fundamental constant, at least in vacuum.
However, it appears that c varies and slows down at the interface between different density materials ie: air to water. But why is this?

If a) photons travel between particles and b) the space between particles is empty then the only reason why c slows is because of the interaction with said particles. If this is the case then why doesn't c slow to nothing whilst travelling and interacting with particles during it's 15 billion light year journey from the edge of the Cosmos to our eyes?

If a) is correct, but b) is not because of the various energy emissions and elemental forces the photons encounter (ie:- do the photons lose energy?) in the less than empty space between particles, then does c vary because of it's interaction with them?

Or is it a combination of factors and if so what are they and what determines their effect/s?

If anyone can answer this query could they e mail me at:

Answers and Replies

  • #2
Staff Emeritus
Gold Member
You should ask this in the Classical Physics forum.