Following your reasoning, which is - again to make sure we're talking about the same thing - turning around has nothing to do with it but ONLY the free (no acceleration/turning/whatever) motion of B in space.
I suppose I made myself understood on this point
I said that both the free motion and the turning around cause a permanent time shift
The former can be calculated using the simple equation of the special relativity
The latter need the much more complicated general relativity theory
I said also that in case of a long journay the former definitely prevail over the latter which can be therefore ignored
The special relativiy only is therefore sufficent to explain the time shift which occur in spatial missions without the need of further complication
How do you explain that B is the older one in the end if NOTHING distinguishes their relative motion?
This question has been asked also by Error014
The twins are identical at the beginning but their Hystories are differnt
a spend the whole life on the earth
b part on the earth and part in the space
It is b who returns to earth ,iit is not a
We are talking about a " principle of equivalence "
Equivalence entails "symmetry" , it does not entail "identity"
There is thereforo no logical contraddiction in the claim " A is older than B"
It is not , of course, an intuitive claim
These are the only serious questions, and you got my answer
The others are only issues...sorry
