Hawking, who passed away last year, was a theoretical physicist, cosmologist, and author who was the director of research at the Centre for Theoretical Cosmology at the University of Cambridge before his death. His scientific works included a collaboration with Roger Penrose on gravitational singularity theorems in the framework of general relativity and the theoretical prediction that black holes emit radiation, often called Hawking radiation. Hawking was the first to set out a theory of cosmology explained by a union of the general theory of relativity and quantum mechanics.
In 2010, Hawking wrote his own Discovery Channel series, “Into the Universe with Stephen Hawking,” where the scientist was voiced by actor Benedict Cumberbatch.
During the programme, he attempted to explain to viewers how a black hole is formed in the cosmos.
He said: “It’s hard to imagine just how dense a black hole would be, but I’ll try and put it into perspective using something familiar – the Earth.
“Imagine, piece-by-piece, I could compress our planet until gravity took over and it became a black hole.
Stephen Hawking made an unexpected discovery
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My most unexpected discovery is that a black hole cannot be perfectly black
“How small would it have to be to vanish down its own gravitational wormhole?
“From 8,000 miles in diameter, I’d have to crush it to the size of a pea.”
However, Hawking’s admitted there was one thing that startled him over the space phenomenon.
He added: “In my years of studying black holes, my most unexpected discovery is that a black hole cannot be perfectly black.
“For much the same reason as the early universe could not be perfectly spread out, there is no such thing as perfection.
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“Black holes must give off radiation, the smaller the black hole, the greater the radiation.
“But only a tiny black hole with only the mass of a mountain range would actually shine.
“Out in space, most black holes are much larger.”
Hawking went on to explain how there are several types of black holes in space.
He continued: “The smaller ones are around four times the mass of our Sun and are 15 miles in diameter.
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“Some are much larger, containing the mass of thousands of Suns.
“And then, there are the really big ones, supermassive black holes, they exist at the centre of galaxies like our own.
“This [type of] black hole is thought to have the mass of four million Suns and a diameter of 11 million miles.
“Black holes like these are the heavy hearts of which galaxies, including our own Milky Way, rotate.”
In episode two, Hawking revealed how NASA could one day use a black hole to time travel.
Stephen Hawking was a professor at Cambridge
He said: “I like to imagine how a spaceship might someday be able to take advantage of this spectacular phenomena.
“Of course, it would first have to avoid being sucked in, the trick I think would be to aim just off to the side so they’d miss it.
They’d have to be on exactly the right trajectory and speed or they’d never escape.
“Get it right and the ship would be pulled into orbit, a giant circle 30 million miles in diameter.
“Here it would be safe, its speed would be enough to keep it from falling any further in.”
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Hawking continued, explaining how time could be slashed in half by following his theory.
He added: “If a space agency were controlling the mission from Earth, or anywhere else far away from the black hole, they’d observe that each full orbit took 60 minutes.
But for the brave people on board close to this massive object, time would be slowed down and here the effect would be far more extreme than near the planet Earth.
“The cruise time would be slowed down by half.
“For every 16-minute orbit, they’d only experience eight minutes of time.
“Round and round they’d go, experiencing just half the time of everyone far away from the black hole.”
Daily Express :: Science Feed