Thanks for that - and for the Einstein link. Nearly impossible to say anything critical about Einstein without offending someone. I adore the man and what he's done, but nobody's beyond the reach of a critical thought or two. His influence on the general view of Time - the block view - is hard to escape. It's very useful. But it's not the only view. To me, what all the marvelous Tensor math is describing is taking the coordinate systems of yore and stretching the grid. The grids still there, just stretched in a few places. As always happens, he based a lot of it, I believe, upon one of the greatest new technologies of the day - film. Cut up the film, slap the frames together so they stack on top of one another, and light the block with a match so it warps. BOOM, block view of spacetime with warping. Add the perspectives of the cameras within the film itself, and you've got the relativity portion. Very clever indeed and extremely useful. It's not that it's wrong - I don't know that - but a lot of stuff can be based upon a single analogy without stopping for a moment to reflect: in exploring this analogy to the limits, am I still using the best analogy for the job at hand?