Black hole as seen in the center of galaxy is the point in a particular point in space where time is equivalent to zero.

Its a space where light don't reaches

To understand is by comparing a white and dark clothing.
White cloth if being wear during sunny day reflects rays of light that feels cooler than wearing a dark cloth during sunny day, because dark absorbs rays of light, being warmer to wear.

Why black hole is black ?
Because it is absence of light as being not to reach out in space,time may come that its area as dark space may fully reach out by energy in form of light.. The thing may happen is repelsion of sorrounding masses which are sources of light energy just like a white clothing reflects rays of light.

Black hole also is part in role playing in conservation of universal and galactic T=me.

I found your post. I have also commented on the black hole topic listed just above you where it asked if the universe could end as a big black hole. Substitute sound waves for light to substitute the Earth for a black hole. The ramjet (afterburner) only works past the speed of sound as the sound wave equivalent of the triode vacuum tube, where velocity gets amplified without moving parts instead of voltage. Red flame from burning oil in a supersonic air flow can move in only one direction, and as it does it adds velocity to the fighter jet plane. The fighter pilot gets to appear like an alien aboard a faster than light UFO to any primitive society that sees him. As for that, the Spanish sent men in shining armor to harvest gold from the Inca Empire who were at first worshipped as gods, which lasted until their sex drives got the better of them.