If neither twin accelerates, they *both* see the other as aging slower. Since they will only meet once, this is no problem. The twin paradox happens when at least one has to accelerate so that they can meet twice. The degree of acceleration will then break the symmetry (or not) and determine which twin is younger (or not). Acceleration is not relative, but velocity is.<quoted text>
We can extend this situation to the good old twin paradox. The claim is that the twin on the space ship ends up aging more (his proper time is the one ticking slower).
The earth is irrelevant here. The only relevant issue with whether the twins meet twice and the pattern of acceleration of the two twins.How would you be able to make this claim? What if Earth had already accelerated to the opposite direction with regard to the path of the traveling twin?
Huh??? What relevance do you think the acceleration history of the earth has in this? What is relevant is the acceleration history of the two twins on their journey. Since they meet twice, at least one has to accelerate. You *do* know what it means to accelerate, right? As in a *change* of velocity? As in, not uniform motion?Earth has accelerated in the universe and you have no idea how much. Therefore you can not predict the aging difference of the two twins. The relativistic model collapses totally.