BP

To me it seems that there is a consensus in physics that our universe is governed by causality.

That is an event (cause) can only cause a second event (effect) where the second event must be in the future of the first one. Basically something from the future can not cause something in the a past. What I would like to find out is weather this is an axiom, a thing we can not prove and just believe in, or is there any theory and experiments that try to prove it.

The more I consider this question the less I see the difference between good and evil.

Conceptually they are different. In all of the experiments I know of are measured the same. I find this equality very unlikely to be a coincidence, so are theories (even bad ones) that try to explain it.

Wikipedia says:"However, in the resulting theory (Relative Theory) gravitation is not a force and thus not subject to Newton's third law, so "the equality of inertial and active gravitational mass [...] remains as puzzling as ever""

I am only interested in arguments against! For example arguments that try to prove it wrong. I am especially interested in twin paradox.

For the spatial coordinates one possibility would be that every direction stretches into infinity. Another possibility is that of a closed space - curving into itself. A demonstration of such a space: a spaceship traveling in a straight line for a very long time would eventually return to the place where it started the travel.

The second part of the question relates to the time coordinate. Can this also be wrapped into itself? Am I correct in assuming that projection to one spatial coordinate + time coordinate is actually a sphere? Could such a topology help explain Big Bang and space growing?

If the hypothesis of a closed universe does hold what is the 5th dimension in which the folding takes place?