“A black hole will suck in any nearby stuff it can. If a star or galaxy is rotating around a black hole this will be meta-stable with the gravity of the black hole matching the rotational acceleration of the star. Various events that produce imbalance, like interactions between different bodies and solar wind, allow the black hole to pick up the resulting debris.
Over time, the black hole will clear out it’s neighborhood. As the universe is expanding, and looks like it continue to do so indefinitely, our black hole will end up alone in a region of empty space.
Hawking radiation is a process at the “edge” of the black hole where quantum randomness results in creation of a particle and antiparticle pair on either side of the event horizon. One falls back into the black hole and the other radiates into space. This will slowly evaporate the black hole. This is a extremely slow process. It relies on the chance creation of particles pairs in a miroscopically thin surface bridging the event horizon. It has been calculated that this would take 10^67 years to evaporate a black hole with the mass of the Sun.
(Compare with the age of the universe, 10^10 years, and you can see how imperceptibly slow this process is. During your lifetime a black hole the mass of the Sun would lose way much than a microgram. By the time the black hole has radiated its mass, all stars will have long burned out, and the universe will have expanded so much that there are enormous and still increasing gaps between everything that even light will never cross.)
If the theory is right, and nothing unexpected happens in the long, long intervening time, the black hole will eventually evaporate in a final flash and all that will be left is an extremely weak radiation in apparent empty space”.
