Or maybe Why is the speed of light what it is?
So why can’t massless particles travel infinite velocity? Also, what is it in the structure of the universe (assuming you are one of those that don’t believe in the aether) that makes c the velocity it is? Why is it not 37 ft/sec or 903 km/hr?
There is some sense in which the speed of light is infinite: No matter how fast you go, it’s still faster. And zero time elapses for a photon between its emission and its absorption, however far away.
As for why it’s the speed it is, the speed of light is 3e8 m/s instead of 37 ft/s or 903 km/hr not because of anything in the structure of the Universe, but simply because of the units we humans have chosen to use. It all makes much more sense, however, if you use the same units for distance as for time: In such units, the speed of light is dimensionless (because you have the same units in the numerator and denominator), and is equal to one.
I thought the speed of light was a function of the permittivity and permeability of what it travels through. Are those fundamental to the universe? And why would the speed of gravity be constrained by the electrical and magnetic properties of the vacuum?
I’m not talking about the units. Why isn’t it 50% of what it is now or 219.673% of its current velocity?
The speed of light is one of a handful of universal constants that seem to have “crystallized” out of the very very early moments of The Big Bang. And that is as far as I’m prepared to attempt an answer with my total lack of qualifications.
I’ve heard that the SoL is the smallest (but non-zero) distance something can travel in the smallest unit of time. As such it would be a function of spacetime itself, it’s most basic and indivisible unit.
You have the cause and effect backwards. Light goes the speed it does because that speed is the fundamental universal constant. And the vacuum permittivity has the value it does because electromagnetic radiation goes that speed.
Gravity also goes the speed it does because it is the fundamental constant. It is not constrained by how fast light goes: They are both constrained by the same universal speed limit.
It’s true that c is 1 Planck distance per Planck time, but that doesn’t really mean much in itself, since that fact is part of how the Planck units are defined. We chose to define the Planck units that way because it appears to reflect a fact about the Universe, not the other way around.
But you are just talking about the units. Or, if you’re not talking about the units, then what are you talking about? Suppose that there were another universe where c were 219.673% of its value in this universe… How would you express that fact, based only on measurements you could make in one universe or the other? You can’t do it by saying that it’s so-and-so many meters per second, because that depends on the definitions of the meter and the second. You can’t say that it’s some multiple of some other speed, because all other speeds are relative.
[QUOTE=kanicbird]
I’ve heard that the SoL is the smallest (but non-zero) distance something can travel in the smallest unit of time. As such it would be a function of spacetime itself, it’s most basic and indivisible unit. ]
[/QUOTE]
If the speed of light was infinite, that would screw up a lot of math as infinite divided by anything non-zero is still infinite. Pretty much any mathematical operation would just be trashed as the result is infinite or infinitesimal.
Why were any of the universal constants created? Does any physicist know?
I know if they were mildly different than life wouldn’t exist which could imply a multiverse among other things. But how/why did the constants develop at all?
“Why” questions are generally beyond the scope of the physical sciences-- Generally, the best you can hope for is “how” (this is in contrast to biology, where the answer to “why” is almost always the same, but “how” is usually quite difficult).
Given that the fine-structure constant, α, is dimensionless and equal to (cμ[SUB]0[/SUB])/(2R[SUB]K[/SUB]), wouldn’t it be different in a universe with a different speed of light?
OK, we can talk about a universe with a different value of the fine structure constant. But if the fine structure constant is different, does that mean that the speed of light is different, or does it mean that Planck’s constant is different, or that the charge of the electron or the strength of the electromagnetic coupling is different? There’s really no single right answer to that question, but most physicists would describe it as one of those last two (if they even distinguish between the last two at all).
Does it really matter though? Couldn’t you attribute it to any of them or any combination of them, provided that the proportions work out?
In any case, what happens if the fine-structure constant changes?
All sorts of things would change with a different fine structure constant, probably enough that Life As We Know It would be impossible. Of course, that doesn’t say anything about Life As We Don’t Know It, and we face the “puddle problem” whenever that comes up.
Douglas Adams reference, no?
Which sorts of things would change?
And also, is there anything constraining the fine-structure constant to be what it is?
One thing that occurs to me - we should change the name of “c”.
I vote for the “speed of causality”. Has the advantage that “c” makes more sense (at least for English speakers.) Also might help avoid the constant implication that it is how fast light photons travel that is the fundamental issue.
Why could you not just measure it? If you’re going to say that it’s because the meter is defined by c, then just use that stupid rod in Paris instead. There are non c related measures of distance.