How does spacetime work?

Answer 1

Y'know, I've been trying to get a handle on that for a long time, but so far I understand it to mean that post-Einstein, once you include time as a fourth axis to the 3 spatial ones, the universe makes sense in terms of our physical laws working everywhere and everytime. That is a neccessity of a good physical law - it must always work no matter where in the universe you test it or how fast you're travelling. In other words, translations and rotations of objects or fields or whatever must have no effect on the validity of the law. If you do not include time as an axis perpendicular to the 3 spatial ones (mathematically, of couse), what we predict won't agree with what we see, especially in such cases as high relative velocities (as in approacing the speed of light), and strong gravitational fields. Amoung the oddest result of this view is that, in truth, all time actually exists simultaneously, and there is some not-quite-understood mechanism that only lets us see one instant at a time.

Anyway, to answer your question, "How does spacetime work?", the answer is, much better than space or time alone and separate. They are, in fact, as inseparable as the pair of poles of a magnet.

This all might be not quite accurate, especially since I'm so far just an "armchair physicist" with no formal education in the area, (tho I'm looking forward to taking physics, including the higher levels, if I can ever get thru these friggin' calculus classes). Anybody else have something to contribute or set me straight on??

Answer 2

Space has three coordinates(X, Y and Z)...So the idea is that time is also a coordinate.

Think about an appointment...You need to know where (XYZ) and when (T).

Answer 3

very well