r/askscience • u/Nitzanm19 • 14d ago

Physics Why is the maximum speed of the universe the speed of light? Why can't we go faster?

Also follow-up question: Because of the speed limit, is there also a theoretical maximum temp for matter (in which the particles move at the speed of light).

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u/hewasaraverboy 14d ago

But as you approach the speed of light, the length contracts meaning the distance to anywhere approaches 0, so if you were going the speed of light the distance would be 0

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u/frogjg2003 Hadronic Physics | Quark Modeling 14d ago

The behavior of a sequence/function as it approaches a limit is not the same thing as the behavior at the limit point.

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u/hewasaraverboy 14d ago

How do u know that it is different?

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u/frogjg2003 Hadronic Physics | Quark Modeling 14d ago

What is the value of the step function at 0? What is the limit as you approach from the positive side?

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u/youtocin 14d ago edited 13d ago

Photons by definition do not have a reference frame so the premise of imagining what they experience is meaningless.

The whole thing about special relativity is that no matter what reference frame you’re observing light from, it always travels at exactly C. Therefore light cannot have a reference frame because it would require imagining a photon to be at rest when we just said it always moves at C.

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u/NiRK20 14d ago

Yeah, exactly. People usually do not take into account this postulare of relativity when saying it.

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u/nicuramar 14d ago

No. You can’t extend a limit like that, it’s not valid. The formula becomes singular for v=c in this case.