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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 lights submits their dark swirling ever-hungry masses

Fascinated thinkers as diverse as Edgar Allen Poe Stephen Hawking and countless science fiction writers

When that 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 in a telescope

Although they were also suggested by the 18th century marquee de la plus 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 you learned of their nature since we found out where they are?

With me on this voyage into the black hole is the astronomer Royals a 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 Melbernell 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 are a

Described into us 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 holds us down

That's why Gagarin had to have a fast rocket to escape from earth's gravity and to escape from the surface of normal star

You would have to fire a rocket at about a thousand kilometers per second

But if you imagine something which is much smaller than the star or much heavier than the star the speed you need to escape from it

...