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Hello, black holes have been described as the dead collapsed ghosts of massive

stars. They have an irresistible gravitational pull, even light submits. Their dark, swirling, ever-hungry mass as fascinated thinkers

as diverse as Edgar Allan Poe, Stephen Hawking, and countless science fiction writers.

When their ominous existence was first predicted by the Reverend John Mitchell in a paper to the Royal Society in 1783,

nobody knew what to make of the idea they couldn't be seen by a telescope.

Although they were also suggested by the 18th century Marquis de la Place and their existence was proved on paper by the equations

Einstein's general theory of relativity, it was not until 1970 that Signus X1, the first black hole was put on the astral map.

What causes black holes?

Do they play a role in the formation of galaxies?

Will they eventually swallow everything up?

And what have we learned of their nature since we found out where they are?

With me on this voyage into the Black Hole is the Astronomer Royal, Sir Martin Reese,

author of many books, including Before the Beginning, our universe and others. He's

professor of physics and astronomy at Cambridge University. Jocelyn Belbonnell

professor of physics at the Open University and professor Martin Ward

director of the X-ray astronomy Group at the University of Leicester.

Martin Reese, you described them as collapsed stars, as black holes.

Can you give a description of how a star collapses and how it becomes a black hole. The star is held together by

gravity and the smaller a star gets or the heavier the star is the stronger

gravity is. We know that in the case of the Earth gravity is what

...