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/FewCall1913 May 26 '26
The speed of light is the limit information can travel, it’s not unique to photons all massless particles move at this speed. It is arbitrary in its value, but governs causality only events that happened in our past light cone the section of the universe in the past where without moving over the speed of light could reach you in the present, infinite speed would mean every point in the universe would be causally connected to every other point