On the OP’s question, you may find this episode of PBS space time interesting.
That is, if you have an IQ of 200+
To summarize the bit at least I think I understand:
The speed of light is better referred to as the speed of causality. It’s the fundamental way space and time are coupled. As accurately as we can measure right now, gravitons also propagate at this speed. There’s nothing special about light; it’s just the first thing we found that moves at this fundamental speed.
It’s possible to show that the speed of causality must be finite based on simple axioms like Galilean relativity.
I didn’t quite follow this part of the video though.
As for why it is 3x10^8 ms-1, well it’s a fundamental constant. We don’t know why it has the value it has.
But of course as the only fundamental speed, we could just as well say it is 1.0, and other speeds should be in “fraction of c in Earth’s reference frame”. But it would make speedometers harder to read.
Because there are some questions that science cannot answer. That is not to denigrate science, but meta-questions like this are unanswerable by the scientific method.
If the speed of light were not 3 x 10[sup]5[/sup] km/sec, things would be different. But that’s not an answer to the question, because things aren’t different.
At a velocity arbitrarily close to c, an anthropomorphized particle has a journey time arbitrarily close to zero and therefore doesn’t see any movement, or indeed anything.
