Check out this diagram for an example of two different worldlines (A and B) without any difference in duration, magnitude or spatial direction of acceleration. The accelerated segments are in red.
Thanks! I stand corrected. The timing of acceleration also matters. I should have known better. Anyway, I agree that
The reason the astronauts age less is that the path they follow through space-time corresponds to a smaller proper time than the path followed by people who remain on the Earth, and the proper time along a path is what a clock following that path measures.
It just seems like a tautology to me (the difference in aging is due to the difference in subjective clocks). To cause this difference one has to make the worldlines diverge, and this means difference in acceleration profiles.
What I initially was unhappy about is the statement
You’re right that Cowen got it backwards, but you’re wrong about this:
Acceleration is what causes the opposite, e.g. turning the spaceship around to come back
Check out this diagram for an example of two different worldlines (A and B) without any difference in duration, magnitude or spatial direction of acceleration. The accelerated segments are in red.
Thanks for this! I had the same misconception as shminux.
Thanks! I stand corrected. The timing of acceleration also matters. I should have known better. Anyway, I agree that
It just seems like a tautology to me (the difference in aging is due to the difference in subjective clocks). To cause this difference one has to make the worldlines diverge, and this means difference in acceleration profiles.
What I initially was unhappy about is the statement
That last statement is perfectly correct.