Thanks for taking the time to respond guys. I understand what you are saying regarding "not staying stationery within an IRF grid" due to the turn-around and acceleration, but this assumes that the IRF grid is (in this instance) the earth.
But supposing there was a second Earth revolving...
Hi all,
Please forgive my simplistic understanding on this, as I am a novice with an interest in Science, but I have the following question:
I've been reading a book on Einstein, and here's the stuff I get:
Speed is relative since there is nothing to "fix" a grid to which we know to be...