We know light from the sun takes about 8 minutes to reach earth. Now let's imagine a reality where light is twice as fast so it takes 4 minutes to reach earth.
What would be our measure of lightspeed in such a reality?
Would it be 6*10^8 m/s ?
My guess is we'd still measure it at 3*10^8 because since light is faster then everything works faster as well, i.e. the clock used to measure the speed is going to run faster.
So even though light takes only half the time to reach earth, clocks run twice as fast so we would end up measuring the same 8 minutes.
Am I right?
Well I guess this is not really about physics, but meta-physics or something.
Speed of light is a constant of our reality (our universe or whatever bigger than that our reality is) and I was just wondering if there is any way that lightspeed could be any other number given the fact that the notion of speed depends on the notion of time and time depends on the speed of light.
It's like trying to define a word using other words whose meaning depend on the word we are trying to define.