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I know similar questions were already here, but anyway, do we know the reason why the measured speed of the light is exactly 299792458ms? Why it is not twice more or half of it? Is there something braking the light in the vacuum down? I mean something like a dark matter or a dark energy? As far as I know the light does not interact with these two (except its probably curved with the dark matter gravity), but anyway, do somebody has a theory why it is exactly like that?

Edit:

The answer I like most:

Kyle Kanos:

Ultimately, the answer is that we don't know. And, at the same time, we don't know if we can ever know why it is this way.

We've measured cc with respect to a unit system that we humans have devised1, but we do not know if there is any reason for it to take that particular value; it simply is what it is.

1 We defined the speed of light as a constant in 1983, so technically the meter and second are determined from cc, not the other way around as I have suggested here.

But if somebody has a theory why it is exactly like that ;)...

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  • $\begingroup$ It seems I have found an answer here: physics.stackexchange.com/questions/3644/… Simply, we don't know why it's like that. $\endgroup$
    – Fis
    Commented May 25, 2017 at 1:47
  • $\begingroup$ I suspect that if it were twice that, or half that, you'd ask why it isn't twice that or half that. $\endgroup$
    – Alfred Centauri
    Commented May 25, 2017 at 1:47
  • $\begingroup$ No, I would ask what is the reason the speed can't be bit faster or slower. But I am interested in reason. No the exact value. $\endgroup$
    – Fis
    Commented May 25, 2017 at 1:48
  • $\begingroup$ There is no theoretical reason, it could take any value. But...en.wikipedia.org/wiki/Anthropic_principle $\endgroup$
    – user126422
    Commented May 25, 2017 at 3:14
  • $\begingroup$ It's just an arbitrary number, it doesn't really matter what you set it to be. Most theoretical physicists set it to be equal to 1 when doing calculations. All that does is change the unit system you're using. $\endgroup$
    – gautampk
    Commented May 25, 2017 at 7:41

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