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.
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".
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.