Re: Basic Science Question - "fabric" of space
General Relativity doesn't explain why gravitational mass curves space-time. It just describes how to calculate the effect based on a set of assumptions about how energy-momentum and space-time interact. Energy and momentum are seemingly joined at the hip just like space and time. Background-independent string theory or loop quantum gravity might eventually offer an insight why the Universe is the way it is, but they haven't as yet.
"After a time, you may find that having is not so pleasing a thing, after all, as wanting. It is not logical, but it is often true." -- Spock -- Flip flap!