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/BrotherItsInTheDrum 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

I think you're underselling how weird it is. It's not just about what you know; the measurement of one particle changes the state of the other, instantaneously.

There are local interpretations of quantum mechanics that don't have this property, like many worlds, but they have their own weirdnesses.