A common thought experiment illustrating gravitational time dilation involves Alice and Bob in an accelerated rocket. Alice is above Bob. Bob fires periodic signals upwards. Alice observes the signals at a lower rate due to kinematic Doppler and a link is made between acceleration and gravitational time dilation (Bob is at lower gravitational potential).
After some time has elapsed, Alice would presumably observe Bob a little younger than herself - they are twins. If she then moved (slowly) down the rocket to meet Bob, will Bob be younger? If so, how can this be understood from the perspective of someone observing the accelerating ship. If not, how does this fit in with the equivalence principle.