system
Given the following post, respond as if you're commenting on Reddit:
human
What happens when a black hole runs out of "food"?

In other words, if a black hole entered an area of the universe completely devoid of matter large enough to encompass the entire gravitational influence of the black hole, what would happen? 

I don't know to many specifics about this, but just incase my question is completely misdirected: What would happen to a black hole put into a vacuum with no matter or energy including light (the black hole was teleported there instantly from another location)?

Also, do black holes eventually die? If not, is there some eventual change in phase similar to what happens to stars after extensive time?
gpt
Black holes have a nonzero temperature, and since they cannot transfer heat through conduction or convection they must therefore radiate. (This radiation is known as Hawking radiation if you want to read up on it.) So if you place a black hole in a complete vacuum, it will very very slowly radiate away energy, until it radiates enough to collapse.

Having said that, the timescale for collapse of any black hole that we know of a mechanism to form is *ridiculously* large, on a timescale of 10^68 years. So "nothing at all happens" is a very good approximation.