It was measured in 1887.
1
They are equal.
how far u can travel at the speed of light in a year
it was faucault who first measured the speed of light in water ......
It's never been measured, but it is assumed to be the same as the speed of light.
there is none.
Hz (hertz) is a unit of frequency, not of speed.
~33 Ohm
The speed of light is a number. It was a theory before it was measured. After it was measured, and the prediction was found to be correct, it was no longer a theory nor a hypothesis. It became a "physical constant".
James Clerk-Maxwell did. He was shown to be correct when the speed was actually measured.
It's never been measured, but it is assumed to be the same as the speed of light.