Jkreider48 said:
The fact that the travel, once returning to "at rest" shows less aging is because of dilations (for the lack of whatever might be the proper term) cause by phenomenons described in General Relativity.
No. There are no “dilations” involved (and also no general relativivity, this all special relativity stuff). The traveler’s clock advances at the rate of one second per second, just like a car’s odometer counts off one mile for every mile the car the car drives. Both the odometer and the clock have a “memory” because they’re counting the miles and seconds; we can look at them and see how many they’ve counted since we last looked.
Time dilation is a different phenomenon, a consequence of relativity of simultaneity. We have two clocks A and B, moving relative to one another. As they pass one another, we set them both to 12:00 noon. Then someone at rest relative to clock A and watching clock B through a telescope calculates that
at the same time that clock A read 1:00 clock B read 12:30 (note that this is a calculation - we have to allow for light travel time between B and our telescope). Thus clock B is running slow by a factor of two.
Meanwhile, someone at rest relative to clock B and watching clock A through their telescope calculates that
at the same time B read 12:30, clock A read 12:15; that is, clock A is the one that is running slow.
So: they disagree about what clock A reads
at the same time that clock B read 12:30. This is relativity of simultaneity, and it is how they both find that the other clock is dilated. Time dilation has nothing to do with the actual tick rates of the clocks (which are tautologically one second per second), it’s all about how we define “at the same time”.
(If you are not already comfortable with the relativity of simultaneity, spend some time understanding it. It is a critical piece of special relativity, without which you cannot make sense of time dilation and length contraction)