To synchronize two clocks that are stationary relative to each other, we send a time stamped light (or radio) signal from the master clock to the secondary clock. Knowing the distance between the two clocks and assuming that light travels at exactly c between the two clocks, the propagation delay is calculated. This delay is then added to the time stamp at the moment that the signal is received and the secondary clock is set accordingly.
As an example, say we have two spaceships at rest relative to each other, separated by exactly one light second in free space. At time 12:00:00 the mother ships sends a light signal time stamped 12:00:00 to the sister ship. The sister ship receives the signal, adds 1 second to the time stamp and sets its clock to 12:00:01.
If we now want to measure the one way speed of light by sending a signal between the two ships, we must obviously get c, what else? My question: is there a way to measure the one-way speed of light without needing two clocks that were synchronized by assuming the speed of light to be c?
SL: Your Aerospace Watchdog