For billions of years you would not see any change in its size or state of rotation. But, there are some changes that are inevitable. According to a discovery by Stephen Hawking back in 1975, because of the quantum nature of the vacuum, black holes slowly evaporate. Black holes that rotate can change by slowly loosing their spin as they absorb matter. Black holes that originally do not spin can be spun-up by accreting matter which carries angular momentum.
Black holes can even increase their mass by absorbing gas and stars in their environment.
This is what is happening near the so-called 'supermassive' black holes found in the nuclei of distant galaxies and quasars. So, black holes can evolve in various ways, but only in the case of evaporation do any of these have to do with the black hole itself. The other examples are changes forces upon the black hole by its surroundings. Dr. Sten Odenwald Return to Ask the Astronomer .