View Single Post
Mar6-12, 06:31 PM
PF Gold
P: 4,695
Quote Quote by PAllen View Post
For me, this was never the point, because I never advocated anything resembling it. I have advocated the following point of view, I believe very consistently (sticking wholly to SR with normal topology for this discussion):

- Acceleration by at least one twin is needed so the twins can get back together. Thus, acceleration somewhere is a necessary (but not sufficient) condition.

- The acceleration isn't the cause of differential aging, nor can the age difference be localized to the acceleration or any other part of the path, in any objective way.

- This formulation of yours: "my only point is although acceleration causes a change in speed, the twin has to accumulate time at that speed in order to effect his aging, the more (coordinate) time and the more (coordinate) speed, the lower his aging during that interval." is fine, I would never dispute it. It is precise and accurate in noting you have to consider segment by segment in some (any) frame.

- I would add that which segments of a journey are associated with 'slower aging' is frame dependent, and not objectively meaningful. But any frame will come up with the same total for a journey.
Excellent--I'm in total agreement. (I better be, it's correct.)