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If photons don’t ‘experience time’ how do they experience space? (kbin.social)
submitted 2 years ago by [email protected] to c/[email protected]
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I have read that since photons have no valid reference frame they don’t experience time. They move through space at c so no time value, in essence.

But space and time are the same in relativity and space obviously affects photons ie they experience eachother. Photons redshift over distance and time, as the most obvious example.

So how is it that a photon can’t “experience time” yet it experiences space? Why isn’t redshifting over X ly considered experiencing time already?

I’m just a layman so I’m having a hard time reconciling a photon not experiencing time due to not having a valid reference frame; but that just doesn’t affect its deal with space? It gets a valid reference frame in space then?

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[–] [email protected] 1 points 2 years ago* (last edited 2 years ago) (1 children)

Redshift depends on the observer, so photons do not "experience" redshift until they are detected in an ordinary reference frame.

Furthermore, I'm not sure there is a good way to define the "experience" of a photon. Photons simply move through space until they interact with matter, and matter is never in the same reference frame as light.

[–] [email protected] 1 points 2 years ago

Yeah I figure “experience” is sort of ambiguous and pop science-y, but it’s how I’ve usually had it explained.

That redshift depends on the observer is obvious now that you point it out and profound too since yeah, I suppose they’re not developing across space in the way I imagined.

This makes me wonder about a potential universe with nothing except photons/radiation in it. They’d just.. never change? Even though they could do things like affect spacetime they pass through or interfere with eachother?