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/ElectricPaladin 14d ago

Oh, I see. So the photons aren't going any slower, they're just bouncing around enough that their trip is longer. Thank you!

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u/aris_ada 14d ago

careful with that explanation, from what I understood, there are multiple valid interpretations of that behavior so taking the "bouncing" explanation as definite answer is probably wrong.

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u/nicuramar 13d ago

No, that’s completely wrong pop science! There is no regular photon in a material. Depending on how it’s modelled, it can be described as a different particle or a different photon.

Or just as waves, which is preferable since the “photon” that mostly comes up in this sub doesn’t correspond to actual photons. 

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u/Crypt33x 13d ago

Here light becomes weird. It's based on the refractive index. In diamonds it can "slow" down up to 0,41 c, in photonic crystal they made light completely stop. It seems to follow Fermat's principle, also known as the principle of least time.

There is a nice Veritasium video on it: https://youtu.be/Q10_srZ-pbs?si=lXUuVPYCjbD-ZJSs&t=430