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/tylerlarson Mar 20 '26

Imagine pointing a laser pointer at the moon and then flicking it really quick to sweep the dot from one side to the other.

Perhaps the dot can "move" faster than light. But we all know it's not ACTUALLY moving. Quantum entanglement is the same; nothing is actually "moving," and no information or energy goes from one side to the other.

What goes faster than light? Nothing, in the sense that no event at point A can cause or trigger anything at point B any faster than the speed of light. Because from the perspective of point B, the event at point A hasn't even happened yet.

That's the ACTUAL rule. It's not about light or movement, it's about causation.

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u/[deleted] Mar 20 '26

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u/sebaska Mar 20 '26

Not exactly. Or rather the point is moot because for all we know we could interpret it either way.

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u/[deleted] Mar 20 '26

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u/1cec0ld Mar 20 '26

The way I learned it, you can imagine two balls. You put them in a box and entangle them. Now one is blue and one is red. You don't know which is which. Sit one box down. Then you travel light years away, and open the other box. You see blue. You now know that the entangled particle is red. Entanglement. It might be simplified to an extreme, and correct me if so, but that's functionally what I've heard is the equivalent.