Nugatory thanks for pointing me to the FAQ. I've started to read it, and already I can see it's going to answer my questions. Can you provide a reference link for the other example?
thanks Cruz, I'll check that out.
Side note, I just read that an inertial observer, in the context of GR, means no force is acting upon him except gravity. Am I interpreting this correctly in that GR differentiates gravity from acceleration?
But to the twin on earth, doesn't the effect of gravity make it seem as though he's constantly accelerating? While the astronaut, once he reaches cruising speed and assuming he is traveling in a straight line, does not feel he's moving?
Maybe I'm confusing the local effects of gravity on Earth...
Ahh ok, so it has something to do with the fact that the astronaut experience some significant acceleration over the period of his travel?
Still not sure how this affects his frame of reference though.
Something sparked my interest yesterday, so I started watching videos and reading about relativity. (This seems to happen every year or so.) I get hung up on the same thing every time!
Many discussions I've seen use the example of an astronaut that takes a trip into space for 10 years or so and...