A person on Earth signals with a laser beam at 6 minute intervals. Another person on a rocket moving away from Earth at 0.600c detects the signals. At what time intervals does the person on the rocket receive the signals from the Earth. The formula we use is: Δt=Δto/sqrt((1-u2/c2)) u = 0.600c I obtained two possible answers: 4.8 min and 7.5 min. However, I'm struggling to figure out which is the proper time and therefore cannot decide which answer is correct.