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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 ;)...

Qmechanic
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Fis
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  • It seems I have found an answer here: https://physics.stackexchange.com/questions/3644/the-origin-of-the-value-of-speed-of-light-in-vacuum Simply, we don't know why it's like that. – Fis May 25 '17 at 01:47
  • I suspect that if it were twice that, or half that, you'd ask why it isn't twice that or half that. – Alfred Centauri May 25 '17 at 01:47
  • 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. – Fis May 25 '17 at 01:48
  • There is no theoretical reason, it could take any value. But...https://en.wikipedia.org/wiki/Anthropic_principle –  May 25 '17 at 03:14
  • 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. – gautampk May 25 '17 at 07:41
  • I got this. But the scale is still the same, correct?. I can also ask, why the light passes exactly the given distance in specified amount of time. Why it is not less or more? – Fis May 25 '17 at 09:30
  • I can also ask, why the light passes exactly the given distance in specified amount of time. Why it is not less or more? Not infinite, jut bit less or bit more. There is "something" what is limiting this value. In another words, there is something that makes the light (and its not just light, it is any kind of electromagnetic radiation and also gravity waves) "travel" exactly the measured distance at specified amount of time. And I am asking, what is limiting it or... setting up exactly this value? Dark matter? Dark energy? Gravity? Anything else? – Fis May 25 '17 at 09:45

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