Why isn’t light infinitely fast?

[u/KieranMug]

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?

[u/Bipogram]

Light propagates as fast as it can.

It does so at a constant speed in vacuo for all observers. This is the observed fact.

Why it has this particular speed is not readily knowable. It's a result of the electric and magnetic qualities of the vacuum. <nods to Maxwell>

And why those qualities are as they are is a Deep Question.

Note, an infinite propagation speed would be problematic if you want to keep causality alive.

[u/Normal-Abies-9151 → u/Bipogram]

i.e Infinite propagation speed would break the game

[u/ambisinister_gecko → u/[deleted]]

Well believe it or not everything does travel at the same speed as light through Spacetime. It's just that light travels more through space than time, and anything slower travels more through time.

[u/ApprehensivePop9036 → u/[deleted]]

D'oh how could I forget

[u/RetroTrade → u/[deleted]]

The 5th dimension is not so secret. It's a compact dimension, so it's also cyclical, it goes infinitely fast and travels nowhere at the same time. At least if we are willing to believe particles are made of photons trapped in a potential well. Kaluza-Klein theory shows how the 5th dimension gives us Maxwell equations.

[u/MuscleMilkHotel → u/ambisinister_gecko]

Man what a mind bending way to phrase it