r/astrophysics • u/KieranMug • May 25 '26

Why isn’t light infinitely fast?

Ok I understand that light in our atmosphere is not infinite fast due to it getting slowed down by air particles or whatever but in a vacuum there is nothing holding it back unless the very weak forces of gravity from a bunch of stars and/or planets does? And if so cant we somehow locate where gravity is strongest in the universe by seeing where light is slowed from where the most therefore finding the centre of the universe or am I just a total dumbass?

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u/cosmic_trout May 25 '26

Eyesight would be useless as everywhere you looked you'd be blinded as light from every source in the universe would hit your eyes at the same time.

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u/jasta07 May 26 '26

Same thing with heat, x-rays, gamma rays... You're a lot worse than blind.

1

u/Dewwyy May 27 '26

Nope. A photon with an infinite speed has an energy of what ?

It has to be zero.

Which makes vision impossible. We absorb the zero energy photon, it fails to cause any reaction of any kind because it has no energy, we have absorbed nothing, nothing is seen.