As far as I understand, even if c is different in some circumstances or changes over time it would be hard to measure because everything else is expressed with c
It’s like trying to measure if your fingers have grown longer, but doing it with only those fingers as a measure
I wouldn’t but it has been historically. Unsurprisingly with mirrors but always under the not insignificant influence of the suns gravity. Our most recent measurements I believe use cosmic bodies I believe which is what makes me wonder if our measurement is accurate. https://www.speed-of-light.com/historical_measurements.html
Oh sorry, I was talking about measuring C rather than 2C (since that is the only way we can get C, IIRC, you cannot measure C directly since SOME information must be conveyed when measurement begins AND ends, hence 2C). For C in a gravitational field, I have no idea but I suspect it will have something to do with relativity and time dilation if it has any effect at all.
well we measure it assuming it has no effect and that is why going way back in this chain I said I would like a measurement outside the influence of a gravity well.
As far as I understand, even if c is different in some circumstances or changes over time it would be hard to measure because everything else is expressed with c
It’s like trying to measure if your fingers have grown longer, but doing it with only those fingers as a measure
so you believe c was never directly measured?
Well, how would you measure C directly? You can only always get 2C.
I wouldn’t but it has been historically. Unsurprisingly with mirrors but always under the not insignificant influence of the suns gravity. Our most recent measurements I believe use cosmic bodies I believe which is what makes me wonder if our measurement is accurate. https://www.speed-of-light.com/historical_measurements.html
Oh sorry, I was talking about measuring C rather than 2C (since that is the only way we can get C, IIRC, you cannot measure C directly since SOME information must be conveyed when measurement begins AND ends, hence 2C). For C in a gravitational field, I have no idea but I suspect it will have something to do with relativity and time dilation if it has any effect at all.
well we measure it assuming it has no effect and that is why going way back in this chain I said I would like a measurement outside the influence of a gravity well.