Theory is as follows Consider any explosion has to throw away energy everywhere surrounding itself. Then Black holes are created in exact same spot from where energy is thrown away Why should it be? In universe its known huge stars after their due life ,die by exploding themselves and the spot where explosion takes place starts retracting the energy given this is were black hole fundamentals come into picture. Black hole starts absorbing the energy that was given away anything thats in its gravitational pull is sucked in . But whats the reason for absorbing whats given away due to explosion. Only reason is this is so if UNIVERSE IS FINITE or expanding at a slow rate by which explosion rate is quite as many thousandth times the expansion of universe rate . So now if know the rate at which energy is being absorbed by black hole we may come to know actual expansion rate of the universe. I personally do not agree to UNIVERSE EXPANSION since energy get increase by itself. If UNIVERSE IS FINITE only then BLACK HOLE theory holds good.

but above is my point of view take it or leave it.