A rocket ship leaves earth at a speed of 3/5 c. When a clock on the rocket says 1 hour has elapsed, the rocket sends a light signal back to earth. When was the signal sent according to clocks on earth? So we have T_earth and T_rocket and they are proportional. I am confused about which side to put the Lorentz factor on. Is it: T_earth = gamma T_rocket or gamma T_earth = T_rocket ? Apparently only earth is an inertial reference frame (see below), so does gamma go with the inertial reference frame? If earth is the inertial reference frame and the rocket is not inertial it must have been accelerating, in which case the problem is inherently wrong because it implied the velocity of the rocket is ALWAYS 3/5c. Am I right? I hate the twin paradox!!!!!!!!!!!!