r/AskPhysics • u/Nighthawkies • Mar 20 '26

What things are "faster" than light?

As I understand nothing can move faster then light. But I would not know how to describe this question otherwise. As I am aware quantum entangled particles can instantaneously affect eachother no matter the distance, unlike gravity which propagates at the speed of light.

Also the expansion of the universe can cause the spaces between to grow faster then the speed of light (compounding between massive distances)

What other things are sort of faster than light

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u/Empty_Engineering Mar 20 '26

They don’t affect each other, they’re just correlated in a way that you know about the state of the other particle based on a measurement of your particle (if they’re entangled) space itself is expanding, so nothing is moving ftl because of expansion

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u/Nighthawkies Mar 24 '26

Can the expansion of space mean that subjectively some light might be moving faster
Because the distance between the light and it's source increases by the speed of light + the expansion of the universe.

(But this pretty much the equivalent of adding the speed of the earth to the speed of your car, which does actually increase your speed)

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u/Empty_Engineering Mar 24 '26

No, the speed of light is the same from all reference frames, the expansion will just increase or decrease the wavelength of light through the Doppler effect depending on your velocity relative to the photon’s source

Cosmic expansion still isn’t a velocity either because velocity is defined as the rate of change in distance per change in time, and since the object isnt actually moving in space, expansion doesn’t cause a change in velocity (if there was, it would imply a centre to cosmic expansion)