Stephen Hawking, who once stunned the scientific community by saying that black holes emit radiation, expounded on another groundbreaking theory on Tuesday.I hate to pick on someone with a degenerative neurological disorder, but Hawking lost it decades ago.
"The message of this lecture is that black holes ain't as black as they are painted. They are not the eternal prisons they were once thought," Hawking told a meeting of experts, according to the New Scientist. "Things can get out of a black hole both on the outside and possibly come out in another universe." ...
"Quantum mechanics — a highly successful theory that describes physical phenomena at the scale of atoms and subatomic particles — says that information can never be lost, even when it falls into a black hole. It is widely believed to be an inviolable law of nature. ..."
During his talk on Tuesday at the KTH Royal Institute of Technology in Stockholm, Hawking proposed that the information of the particles sucked into a black hole eventually makes it out in the radiation that is emitted by a black hole.
The information emitted, however, is not usable. ...
"At Monday's public lecture, he explained this jumbled return of information was like burning an encyclopedia: You wouldn't technically lose any information if you kept all of the ashes in one place, but you'd have a hard time looking up the capital of Minnesota."
First, nothing in quantum mechanics says that info can never be lost. Some of the processes are time reversible, so you could say that nothing is lost in those processes. But there is nothing special about information, and quantum mechanics is not a time reversible theory.
Second, there is no "inviolable law of nature" that says that info can never be lost. Just ask yourself: Who got the Nobel Prize for that? What is the experiment demonstrating it? What is even the theoretical basis for it? What useful consequence does it have? The answers are no one and nothing, because there is no such law.
Third, if there is some definition of information that allows an encyclopedia to be burned without losing any of it, then it is unrelated to every definition of information that I know. It is crazy to argue that burning an encyclopedia conserves information.
Fourth, it takes a trillion trillion years for a black hole to evaporate, so this is completely disconnected from any observational science.
People make fun of medieval scholars for supposedly debating about How many angels can dance on the head of a pin? This is the modern equivalent. Someday people will make fun of XXc and 21c physics for arguing about this stupid issue.
Update: Lubos Motl weighs in on this issue, and says that you have to be a string theorist to understand the finer points.