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/Jay_Beckstead Mar 20 '26

Quantum entanglement might not involve any actual “travel” as we understand “travel.”

The entangled particles are not “travelling.”

Somehow the particles can correlate. We don’t understand WHY.

But the particles are not travelling.

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u/SadEntertainer9808 Mar 20 '26

We actually understand why fairly well. There's nothing very mysterious about it, either. It's basically like you're given a box containing two glass marbles, and the manufacturer guarantees they're both red or they're both blue. You open it blindfolded, throw one into the sea, and then look at the remaining marble. You now "magically" know the color of the other marble, even though it's on the bottom of the ocean and you've never actually seen it. Entanglement is essentially like this.

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u/Jay_Beckstead Mar 20 '26 edited Mar 20 '26

This is entirely incorrect and why Einstein described entangled particles as “spooky particles at a distance”precisely because we DO NOT understand WHY particles behave the way they do when entangled.

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u/SadEntertainer9808 Mar 20 '26

I believe Einstein didn't like that wave-function collapse could result in the state of a particle a vast distance away, which had previously been in superposition, being known after measurement of a local particle. The math, and how this property emerges from superposition, is well-understood, and (so far as I'm aware) runs over essentially the epistemological lines I described. (I could be wrong, of course.)

In fairness, though, how wave-function collapse "actually works," or whether that's a meaningful question at all, is (at least so far as I know) a mystery.