I’ve heard this as I’ve had a look at special relativity, but I don’t get why.
In: Physics
“Why” is rarely a question for science. It’s indeed very counter intuitive that the speed of light (in a vacuum) is independent of reference frame, and leads to tons of weird relativity effects. I wouldn’t blame anyone who wants to know why
If the question is “how”, the answer is that time itself changes, because time (and space) are not truly a simple as we experience it in our typical human conditions. It’s a bit like how an ant might think they are standing on an infinite plane, even if their world was a sufficiently large donut. We experience such a small fraction of the universe in such a small range of conditions that we aren’t prepared to imagine it at such different scales.
In the case of relativity, I’m referring to conditions of incredibly high amounts of mass (black holes bending space) or speed (photons, neutrino experiencing time differently).
Everything about it makes no sense to us – it feels extra complicated and chaotic – but that’s only because our little experience is so simplified. We are the ant on a doughnut asking “Why” their world isn’t simply flat
That’s just the way the universe is. As far as we can tell, c is just constant, with no “reason” for it to be that way other than that this is the way it works. “Why” questions are notoriously difficult for physics to answer, because at some point you will always get “just because that’s how it is”.
There is no reason, or at least we don’t if there is one, that’s just how the universe works, it’s weird, but it we noticed that anything without mass travels at the speed of light, no matter your frame of reference
I’m going to encourage some pretty heavy viewing of the PBS Spacetime channel on everyone’s favorite streaming short-form video platform. The constant speed of light in a vacuum (It does change speed in a material but I feel confident that isn’t what you are asking) is very closely tied to the concept of causality. As to why it is what it is, we don’t really know why it isn’t say 3% faster or slower.
We do know that in order for certain other things to work properly the speed of light has to be what is called invariant, which is a fancy way of stating that any observer needs to be able to reach the same conclusion about its speed. Since causality has to do with very important things being able to work the way they do (like atoms being able to hold together), asking what happens when you mess around with that inevitably leads do discussions of the Anthropic Principle.
TL;DR Because that is the speed of information in this universe. An unsatisfying answer, yes but you’ve got to get into the weeds a bit if you want a more satisfying one.
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