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Stephen Hawking's final scientific paper, 'Black Hole Entropy and Soft Hair', released

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LONDON: Stephen Hawking's final scientific paper has been released by physicists who worked with the late British cosmologist on his career-long effort to understand what happens to information when objects fall into black holes.

The work, which tackles what theoretical physicists call "the information paradox", was completed in the days before Hawking's death in March. It has now been written up by his colleagues at Cambridge and Harvard universities and posted online, the Guardian reported on Wednesday.
Malcolm Perry, a professor of theoretical physics at Cambridge and a co-author on the paper, "Black Hole Entropy and Soft Hair", said the information paradox was "at the centre of Hawking's life" for more than 40 years.

Stephen Hawking Leaves Behind His Legacy In The Form Of Books
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Stephen Hawking was a prolific author with a knack for making books on challenging scientific topics engaging to a wide spectrum of readers.

The physicist is best known for his best-selling 1988 classic 'A Brief History of Time: From the Big Bang to Black Holes,' which was intended to help people without a strong scientific background understand key questions of physics and human existence. In it, he discusses the origins of the universe and its future. Among his other books are:

(Image: Reuters & www.hawking.org.uk)
Stephen Hawking was a prolific author with a knack for making books on challenging scientific topics engaging to a wide spectrum of readers. The physicist is best known for his best-selling 1988 cla..
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Written by Hawking and his daughter, Lucy, this was a series of illustrated children's books to explain 'secret keys to the universe' to younger readers. The books deal with complex topics including the Big Bang.

(Image: www.hawking.org.uk)
Written by Hawking and his daughter, Lucy, this was a series of illustrated children's books to explain 'secret keys to the universe' to younger readers. The books deal with complex topics including ..
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A very personal memoir published in 2013 in which Hawking deals among other things with his childhood, his evolution as a thinker and scientist, the impact of his ALS diagnosis when he was 21 and the ways in which the prospect of an early death affected his work.

(Image: www.hawking.org.uk)
A very personal memoir published in 2013 in which Hawking deals among other things with his childhood, his evolution as a thinker and scientist, the impact of his ALS diagnosis when he was 21 and the..
Read More
Hawking said this 2010 book co-written with American physicist Leonard Mlodinow was intended to address important unanswered questions such as why there is a universe and whether the universe needed a creator and designer. Hawking said his thinking had been influenced by significant advancements in physics that had followed publication of 'A Brief History of Time.'

(Image: www.hawking.org.uk)
Hawking said this 2010 book co-written with American physicist Leonard Mlodinow was intended to address important unanswered questions such as why there is a universe and whether the universe needed ..
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Published in 2003, Hawking writes about the great astronomers and physicists who preceded them, presenting in a single volume a vast history of the field that makes heavy use of original papers by Einstein, Copernicus, Newton and many others. Hawking puts each in context and explains their role in altering the course of science as mankind moved out of the Middle Ages.

(Image: www.hawking.org.uk)
Published in 2003, Hawking writes about the great astronomers and physicists who preceded them, presenting in a single volume a vast history of the field that makes heavy use of original papers by Ei..
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This best-selling 1994 collection includes a mix of personal and scientific essays.

(Image: www.hawking.org.uk)
(Text: AP)

This best-selling 1994 collection includes a mix of personal and scientific essays. (Image: www.hawking.org.uk) (Text: AP)


The origins of the puzzle can be traced back to Albert Einstein.

In 1915, Einstein published his theory of general relativity, a tour-de-force that described how gravity arises from the spacetime-bending effects of matter, and so why the planets circle the sun.

But Einstein's theory made important predictions about black holes too, notably that a black hole can be completely defined by only three features: its mass, charge, and spin.
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Nearly 60 years later, Hawking argued that black holes also have a temperature and because hot objects lose heat into space, the ultimate fate of a black hole is to evaporate out of existence.

"The difficulty is that if you throw something into a black hole it looks like it disappears," said Perry.

"How could the information in that object ever be recovered if the black hole then disappears itself?"

In the latest paper, Hawking and his colleagues show how some information at least may be preserved.

The physicists show that a black hole's entropy may be recorded by photons that surround the black hole's event horizon, the point at which light cannot escape the intense gravitational pull. They call this sheen of photons "soft hair".
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Among the unknowns that Perry and his colleagues must now explore are how information associated with entropy is physically stored in soft hair and how that information comes out of a black hole when it evaporates.


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