Hello. I was thinking about gravity and how matter bends the ST (space time) creating gravity.which lead on to singularities. I wondered how much mass it would take to either make a hole in spacetime, or how much it would take to make a black hole. So I googled it. This is where my confusion became apparent. Firstly: Are black holes literal holes in St, or are they just warps(I think it's the right Word) so much that matter can't get out, like a spider in a bath tub. Secondly: it is not just mass that effects ST , but energy too. Is it every type of energy in a scenic body? Such as as the Kinetic energy, potential energy and electric? Even links to useful websites and papers will be great. Thanks.