Comment by fiddlerwoaroof
2 years ago
The relation between the meter as defined and the speed of light isn’t arbitrary. But the value of c in terms of meters isn’t really privileged compared to the value of c in parsecs: both numerical values are only the number they are because you’ve picked an arbitrary unit to measure them by.
Right. It's not so much that the speed of light itself is arbitrary, it's that the number 299,798,452 is arbitrary. Humans picked it because they liked those units for distance and time.
If we had two different types of universal-constant speed, we could measure the ratios between them. But there's only c.
Charges of elementary particles, on the other hand, we do have multiple examples. And whether we call an electron "-1" or "4895", there is an exact ratio between different particles that is an intriguingly simple number.
The ratio being such a simple number tells us something about the universe, in the way that most constants don't.
Or to put that another way, "299,798,452" is derived from both facts about the universe and arbitrary human choices. "1/3" is only derived from facts about the universe. It being such a simple number then begs for explanation, because humans didn't intervene to make it such a simple number.
And on top of that, if the speed of light or gravitational constant changed by .00001, nothing would happen. If the electron and proton didn't match perfectly, a ton of stuff would break.