Lisa, come look at something I wrote and posted at a physics forum

[Lisa]

As for gravity the current idea is that an object of mass bends the space time and it is the space time that acts on the object to cause it to fall towards the other object. The idea is like if you hold out a sheet flat and put a marble on it the marble would cause the sheet to sink in the middle and other marbles you drop onto the sheet are going to fall towards the original marble because the fabric has been bent