That last post, though accurate in spirit, is not quite the literal SR view, as I have noted elsewhere. Even in SR, the train is deemed to be the thing moving when it "takes off." At that point, it is accelerating and accelerated motion is absolute, even in SR. But here's what SR does claim: That train could accelerate at a slow rate for hours, and it would, during that whole time, be "moving." But the instant it quit accelerating, and moved at a uniform speed, it would then stop on a dime and become absolutely motionless. The earth would then suddenly start moving at the speed that the train was (say 80 mph). All instantaneously.
If this train happens to be east-bound and there is a west-bound train on tracks 10 feet away, well, then, the earth starts moving in the opposite rotational direction for THAT train. In either case, the passengers on each train never move an inch. Yet, for some strange reason, they quickly move out of sight of each other. Go figure, eh?
The rational view, as held by LR, is that all motion, both inertial and non-inertial, is absolute, not relative. What was absolute motion a split second ago does not suddenly become relative just because you have stopped accelerating.
Edited by Moronium, 13 June 2018 - 02:23 PM.