Stephen Hawking’s final paper explores disappearing black holes


The final paper that famed physicist Stephen Hawking worked on before he passed away has been published and it deals with a topic bigger than Hawking’s legacy – what happens when objects fall into black holes?

The paper entitled “Black Hole Entropy and Soft Hair,” looks into whether black holes keep the information of the things that fall into them. Some theoretical physicists believe they do, while others do not.

Hawking argued that because black holes have temperature and hot objects ultimately lose their heat in space, black holes eventually evaporate and disappear. One of the paper’s co-authors, Malcolm Perry, told The Guardian that it looks like items disappear.

“The difficulty is that if you throw something into a black hole it looks like it disappears,” Perry told the website. “How could the information in that object ever be recovered if the black hole then disappears itself?”

The sheens of photons that surround a black hole’s event horizon are referred to as a “soft hair” in the paper.

“Assuming the existence of a quantum Hilbert space on which these charges generate the symmetries, as well as the applicability of the Cardy formula, the central charges reproduce the macroscopic area-entropy law for generic Kerr black holes,” a summary of the study says.

Hawking, known for writing the best-selling book “A Brief History of Time,” teaching physics and mathematics and delivering impactful speeches, passed away in March 2018 at the age of 76.


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