A black hole is born when an object becomes unable to withstand the compressing force of its own gravity. Many objects (including our Earth and Sun) will never
become black holes. Their gravity is not sufficient to overpower the atomic and nuclear forces of their interiors, which resist compression. But in more massive
objects, gravity ultimately wins.
Stellar-mass black holes are born with a bang. They form when a very massive star (at least 25 times heavier than our Sun) runs out of nuclear fuel. The
star then explodes as a supernova. What remains is a black hole, usually only a few times heavier than our Sun since the explosion has blown much of the stellar
We know less about the birth of supermassive black holes, which are much heavier than stellar-mass black holes and live in the centers of galaxies. One
possibility is that supernova explosions of massive stars in the early Universe formed stellar-mass black holes that, over billions of years, grew supermassive.
A single stellar-mass black hole can grow rapidly by consuming nearby stars and gas, often in plentiful supply near the galaxy center. The black hole may also
grow through mergers with other black holes that drift to the galactic center during collisions with other galaxies. Astronomers are actively investigating
these and other scenarios through observations and computer simulations.
The Large Hadron Collider is a 17-mile long particle accelerator in Switzerland that may reach energies high enough to create miniscule black holes.