Why is the speed of light 186,000 miles per second?

In summary, the speed of light is 186,000 miles per second because of the specific values for the electric and magnetic constants in free space, as described by Maxwell's equations. However, the reason for these values is unknown and it is similar to the unknown value of Pi. The existence of an "ether" through which light travels has been disproven by various experiments and there is no edge to the universe. The concept of an "ether" is no longer used in modern physics.
  • #36
the universe cannot look the same in all directions, that doesn't make sense at all. Everything you guys say is speculation, and you are criticizing my question. I don't want you to answer it with facts. i know that is impossible. But I am a person that tries to think outside the box. you say that space is a vacuum, there is nothing there, then all of a sudden there is dark matter and dark energy, which no one can see, yet you are ok with believing that. And your right nugatory, I apologize for asking this here.
 
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  • #37
thejun said:
the universe cannot look the same in all directions, that doesn't make sense at all.
Have you looked? It is an observational fact that, to the limits of accuracy of our devices, the universe is indeed isotropic on a large scale (which is what people mean when they use the less precise "looks the same in all directions"). One of the harder lessons for humans to absorb is that the universe really doesn't care what we think makes sense - it is the way it is.
... you say that space is a vacuum, there is nothing there, then all of a sudden there is dark matter and dark energy, which no one can see, yet you are ok with believing that.
The dark energy and dark matter hypotheses do not disagree in any way with the experimentally confirmed theories of how a vacuum behaves, and "space is a vacuum" is a misstatement of what scientists say about what's in space. Yes, you will hear even professional scientists say "space is a vacuum" when they're speaking to a non-technical audience... but that's a simplification for a non-technical audience. A strictly correct description would be something along the lines of "a perfect vacuum is a very good approximation for outer space; there's a little bit of stuff, maybe a few atoms or so, in every cubic meter of space, but so little that its effects are locally negligible".
 
  • #38
We can close this thread at this point. The original question has been answered, and the subsequent discussion into other topics that should be discussed in their own threads or not at all.
 

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