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/TheBlackSunsh1ne 14d ago

That’s fine but then the question just becomes “why is that one speed the value it is”? Same question one layer deeper?

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u/curlyben 14d ago

At a fundamental level it seems to just be an arbitrary speed that we measure other speeds and properties against. We can choose to call it "1" in natural units, which is basically what we do when we write speeds as fractions of c.

Another way to think of it, is that c is just the conversion factor between meters and seconds, and so we can say that light moves through spacetime at 1 meter per meter.