Is the speed of light measurement dependent on the tick rate of different clocks? Hello I want to ask the following questions: If Clock A is undergoing only a natural gravitational time dilation, and possesses 0 rate of change in time dilation, and if it is measuring seconds at a different rate than Clock B, which for our purposes is a clock at higher gravitational potential where the seconds are different - what if: Clock A was used in a measurement of the speed of light, and the value for this clock reads 1 second within which light travelled 299,792,458 meters. However, Clock B, which we will assume to have 0 relative velocity with Clock A, being in a higher gravitational potential, reads 1.000001 seconds passed. If you take the "distance traveled by light / the time passed for Clock A", you will get a different value than "distance traveled by light / the time passed for Clock B". Of course, you could take the reverse, where you have, say, 1 second passing for Clock B and .99999 seconds for Clock A Am I getting this right?