They will eventually evaporate, if that's what you mean. But it takes a long, long time for a typical black hole to evaporate - much longer than the current age of the Universe.
Black holes (in the astronomical sense) have never been made in the laboratory.
never
They don't. They never have. They never will.
Black holes are so powerful, that if you were in one, it would stretch you apart and you would NEVER come out!!!
The Earth has never been endangered or harmed by a black hole, and chances are, never will be.
Astronomers are constantly investigating and collecting information on any objects in space that have not yet been cataloged. In the course of doing this, they find and identify galaxies, nebulae, novas and, of course, black holes. They just "turn up" frequently as part of the never-ending search of the universe and the objects in it.
That's what the mathematical theories suggest would happen. We have never observed this, and with any luck we never will be close enough to see this. Black holes are dangerous places.
I've never heard of a black "whole," but yes, supercolliders can produce black holes.
The black holes may not devour everything since the outward velocity of the matter in the universe may escapethe gravitational pull of the black holes. Stephen Hawkins reckons that even the mass in the black holes would diminish over time, though over trillions and trillions of years.
While scientists have never actually SEEN a black hole (they are called "black holes" because their gravity is so great that not even light can escape!) we believe that super-massive black holes are at the hearts of most galaxies. These super-massive black holes might be the mass of a million stars the size of the Sun, or larger.
While we have never actually proven that this does happen, we're fairly certain that when two black holes get close enough together, they will merge and form one even larger black hole.
stellar black holes were stars (these are large)primordial black holes were pieces of the big bang (these are microscopic)