How can gravity grasp on space time?...How can matter produce gravity..
nobody really knows HOW such a thing can happen. That's likely because nobody knows exactly what gravity, nor space, nor time, nor even energy is. Sounds crazy, but all those entities apparently were 'unified' really, really early in the universe...at extremely high and unstable energy levels...meaning at those early times all the entities were the same...maybe roughly like a 'quantum foam' if you know that term...
In any case, those early unstable conditions underwent a 'spontaneous symmetry breaking'
and, voila, everything you see around you emerged or developed. So today we see a bunch of characteristics around us and are trying to figure out how they are related. For example, in special relativity Einstein deduced that space and time are not constants as they superficially appear to us...He grabbed relationships from Lorentz and Fitzgerald and Maxwell and with brilliant insights concluded: the speed of light is constant, not space, not time!
But as already noted in prior posts, it turns out we HAVE codified our observations about how most of gravity works...we have math that matches observations...via the Einstein stress energy tensor and field equations, for example...these seem to capture MOST situations... from most of black holes to most of the universe...not bad!
But what happens to gravity space and time at 'singularities' is not yet understood...so the progress continues.
