How does an IFR observer measure the speeds of two craft going oppisite directions approaching "C"?
Take the example that an observer (“Rick”) is standing on earth. Now obviously from Einstein we know a ship cannot travel faster than the speed of light. So lets have two ships travelling 0.95c in either direction away from each other.
So how can the person on earth measure their relative speeds? Wouldn’t the earth observer see them travelling 1.9c away from each other?
Obviously in either ships (say ship “A”) reference frame, the length dilation affects the measured velocity of the other ship (Ship “B”), such that the measured velocity of the other ship (Ship “B”) is less than the speed of light.
But to the observer on earth, how would they calculate the relative velocities of each ship? Surely what he measures is greater than C.
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