einstein himself did not have the idea of a "black hole", but later scientists used this name for an object in the universe that bends spacetime so much that not even light can escape it. they think that these ultra-dense objects are formed when giant stars, at least three times the size of our sun, die. this event can follow what is called a supernova. the formation of black holes may be a major source of gravitational waves, so the search for proof of gravitational waves has become an important scientific pursuit.