0

Two massless objects exist in a flat spacetime, objects A & B. A has a velocity of 0.866c, moving directly away from B, from the frame of reference of B.

B will perceive A's time to be passing at 50% of B's time, and, due to relativity, A will perceive B's time to be passing at 50% of A's time.

If A stops at a distance from B, and instantly reverses it's velocity, returning to B, A will perceive B's time to have only progressed half as much as it's own time, but B will perceive A's time to have only progressed half as much as IT'S own time.

The result of this is that, if the two are separated at their inception, upon A's arrival, A will perceive B to be half it's age, and vice versa, both of which cannot be correct.

How can this be reconciled with the conclusion of the twin "paradox", in which the "stationary" observer is truly the one who is older than the one who was "in motion".

I am aware that this may not truly be a reconciliation, and might instead simply be a correction of a misunderstanding.

Kieran Moynihan
  • 836
  • 5
  • 15
  • 1
    The setup you're giving is completely identical to the twin paradox. You're essentially asking, "why is the twin paradox not a paradox", which is a question that has been asked and answered hundreds of times on this site! But rest assured, there is no paradox. If "A" and "B" are emitting radio waves the whole time, say dots of Morse code a period $t$ apart, "A" does in fact receive $T/t$ dots ($T$ being the total time A's trip took according to B), and "B" does in fact receive $T/(\gamma t)$ dots. The asymmetry is now apparent (draw a Minkowski diagram!): (cont.) –  Nov 16 '16 at 08:00
  • at first "A" is moving away from the signals, so they occur less frequently in its frame. Afterwards, "A" is moving towards the signals, which are already flying freely in space. It's scooping up the signals and so observes them more frequently for its whole trip back. On the other hand, "B" observes the redshifted signals for most of the time, until all of a sudden (just before A's arrival), a bunch of blue-shifted signals slam into it all at once. –  Nov 16 '16 at 08:00

0 Answers0