Why is the speed of light 299792458 meters per second and not a bit more or less?

Answer 1

The speed of light was predicted before it was ever measured. If you write the

differential equation of a wave, there's a very definite place in the equation where

the speed of the wave appears.

The Scottish Physicist James Clerk-Maxwell took four equations of electricity and

magnetism that had been discovered by earlier scientists, and succeeded in

mashing them together to come up with the equation of an electromagnetic wave.

Right there in the spot where the wave speed should be was the quantity

[ (electrostatic permittivity of space) x (magnetic permeability of space) ] .

Both of those properties of space had been kind-of measured by Maxwell's time,

but now it suddenly became very urgent to go back and work on measuring them

with the utmost accuracy ... and at the same time, to figure out a way to measure

the speed of light. Because if that quantity could be shown to match the real speed

of light, then we would know that light is an electromagnetic wave, and that Maxwell's equation for it is an accurate mathematical description of it.

You asked "Why is that the speed of light ?" The answer is: Because light is an

electromagnetic wave, therefore its speed is determined by those two properties

of free space, and the values of those two properties of space happen to be

such and such."

Now, we can almost hear you asking "Why are the values of those two characteristics

of space the numbers that they are, and not a bit more or less ?"

All we can tell you is that there are cosmologists who are actually working on that

esoteric question, along with the question of why other properties of the universe (For example, the gravitational constant.) are the numbers that they are. One realization that has emerged is the fact that if a few of the constant numbers of nature were just slightly different from what they actually are, then life would not be possible.