[simplified (OP)]

Are photons faster in cold or hot transparent environment?

[yor_on]

Simplified
I'm sure you have a certain meaning with that question.
So, what do you mean by a hot/cold 'transparent' environment?

Photons are photons as far as I know?

But if we assume a very cold environment, a Bose/Einstein condensate?

[MikeS]

They are the same but time passes faster in a hot environment and slower in a cold one.  So looked at from the perspective of a distant observer they would appear to travel faster in a hot environment.  The photons in the hot environment would complete their journey sooner than the photons in the cold environment.  Both sets would have taken the same local time but a second is shorter in the hot environment.

[Soul Surfer]

Presumably the questioner is talking about normal solid liquid or gaseous environments and not plasma environments Which are much more opaque to photons because of the different sorts of interactions

Photons travel slower than the vacuum speed of light in normal transparent materials and as materials usually become less dense (ie expand) a temperature rises the refractive index (a measure of the difference in the speed of light between two media usually falls i.e. the photon velocity rises as the temperature goes up but this is not always the case near to frequencies where light may be absorbed.

[simplified (OP)]

Simplified
I'm sure you have a certain meaning with that question.
So, what do you mean by a hot/cold 'transparent' environment?

Photons are photons as far as I know?

But if we assume a very cold environment, a Bose/Einstein condensate?

There is time frozen?

[simplified (OP)]

They are the same but time passes faster in a hot environment and slower in a cold one.  So looked at from the perspective of a distant observer they would appear to travel faster in a hot environment.  The photons in the hot environment would complete their journey sooner than the photons in the cold environment.  Both sets would have taken the same local time but a second is shorter in the hot environment.

And so does cold environment take much time for own needs?

[simplified (OP)]

Presumably the questioner is talking about normal solid liquid or gaseous environments and not plasma environments Which are much more opaque to photons because of the different sorts of interactions

Photons travel slower than the vacuum speed of light in normal transparent materials and as materials usually become less dense (ie expand) a temperature rises the refractive index (a measure of the difference in the speed of light between two media usually falls i.e. the photon velocity rises as the temperature goes up but this is not always the case near to frequencies where light may be absorbed.

Does density eat time?I think low energy has high ability to eat time.Yes, smaller volume resieves less time.

[yor_on]

You're connecting the dots, right?

Thinking of if it could be possible that 'change' is 'energy expended', and that without 'change' (as in a Bose Einstein condensate) there is no energy expended and if now change also would be a description of a arrow?