What is a Black Hole?
First suggested by Albert Einstein's equations, a black hole is space and time twisted into a furious knot. Scientists now believe it is the largest and most powerful object in the universe, and yet it emits no light.
A black hole is a region of space where the pull of gravity is so immense that not even light can escape it. Nothing survives encounters with black holes.
A black hole can be a million times the mass of Earth, but compressed so tightly it literally exits the known universe.
Some scientists have theorised the existence of a wormhole inside black holes. A wormhole is a tunnel through space and time, which leads to a strange door known as a white hole. Here the twisted logic of extreme gravity goes into reverse. Instead of being sucked in, you'd be catapulted out to the far reaches of time and space. But to where? In science fiction, wormholes offer handy escape routes to other universes. In reality, the inside of a black hole is probably too chaotic and violent for a wormhole ever to form.
125 billion galaxies that make up the visible universe, and nearly all the large ones bear the signature of a super-massive black hole.
Black holes can have a creative aspect; blasting waves from supernovas spread heavy elements generated in the core of the galaxy, setting the stage for the formation of new solar systems.
How Are Black Holes Created?
Black holes are a product of the familiar universe of stars and gravity. They have their genesis in a type of enormous star called a 'Red Super-giant.'
A Red Super-giant star is 10 times heavier than our Sun yet it will burn itself out in a fraction of the Sun's lifetime. Deep inside - the crush of gravity sends temperatures soaring above a billion degrees. Helium and carbon fuse into heavier elements - oxygen, silicon, sulphur.
When a Red Super-giant star implodes under its own immense gravity, it sends a shock wave roaring out. The star now goes Supernova in a violent explosion. What is left is a dense core of subatomic particles - a neutron star - only about 28 kilometres across. It's so dense that a teaspoon of neutron star matter would weigh about a billion tons. Eventually the gravitational pressure will be so large that the neutrons themselves will be crushed and there will be nothing left to stop the collapse – which is when a black hole is born.
When galaxies collide, the black holes at each their centres merge and grow.