That's what I would have said. The traveller knows he's traveling and where he's going to return. When I drive to the corner market, I assume a frame in which I'm the one moving, which makes more sense than a frame that has the whole Earth accelerating each time I take a corner. If I'm not going back somewhere, then there is no reason to assume a frame like that, and there's no particular reason to concern ones self with the 'current' age of some distant relative. Nobody has a current age. It's spacetime, which doesn't posit a preferred moment. So what advantages do all these methods claim? What is the advantage of yours? I certainly don't see one. They do no such thing, and you've failed to support this assertion after I pointed it out. All they're doing is a computation, not actually causing any effect at all. Predicts? I understand that it computes this, but it is hardly a prediction. A prediction anticipates some empirical difference that the other methods do not. Anyway, the Andromeda 'paradox' has long demonstrated the age of distant things changing relative to a mildly accelerating object, such as pacing back and forth. There's nothing magical about continuously changing the frame in which you are stationary. If a physicist is bothered by the fact that multiple non-parallel lines converge on the same point and even (gasp) cross each other, maybe they're in the wrong business.