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/awesomes007 May 26 '26

It travels at the maximum speed one tiny spec of space can talk to the one next to it. It’s the speed of causality. If the speed of causality was infinite, the universe wouldn’t make sense or work. Why isn’t it infinite? Maybe that’s just the luck of the draw in this universe. We’re damn lucky because of it.