My understanding of "local flatness" is the following. Around any spacetime point (with local flatness), there exists a region of spacetime (a neighborhood) within which the results of any experiment cannot be distinguished from the results of an experiment performed in completely flat...
I guess my question wasn't as clear as I intended. I will try to explain differently. If we let time (t) go to the "additive inverse" of time (-t), the equations of motion that we currently have remain the same. There is a symmetry there. My curiosity is this: Is there a set of parameters that...
It is obvious that there is a one-to-one relationship between real numbers (defined to include infinity) and their multiplicative inverses (assuming we map the inverse of zero to infinity and vice versa). Thus, one should be able to replace the distance between two points in space with it's...
Not sure what I'm supposed to write here. I just hope I can use this forum to get a few questions answered about physics...and possibly help someone else understand something better.
Suppose an observer (O) sees a traveler (T1) pass by at time t=0, moving a speed 3c/5. Five years later (according to O), T1 returns. If we assume that T1 traveled at 3c/5 for half the journey and instantaneously reversed direction, returning at the same speed, we can calculate that T1 aged only...