A new study finds that – contrary to what some physicists have argued for the years – information is not lost once it has entered a black hole. The research by the University at Buffalo presents calculations showing how information is, in fact, preserved.
“According to our work, information isn’t lost once it enters a black hole,” says Dejan Stojkovic, associate professor of physics at the University at Buffalo. “It doesn’t just disappear.”
The research marks a significant step toward solving the “information loss paradox”, a problem that has plagued physics for almost 40 years, since Stephen Hawking first proposed that black holes could radiate energy and evaporate over time.
This posed a huge problem for physicists because it meant that information inside a black hole could be permanently lost when the black hole disappeared – a violation of quantum mechanics, which states that information must be conserved.
The paper outlines how interactions between particles emitted by a black hole can reveal information about what lies within, such as characteristics of the object that formed the black hole to begin with, and characteristics of the matter and energy drawn inside.
This is an important discovery, Stojkovic says, because even physicists who believed information was not lost in black holes have struggled to show, mathematically, how this happens. His new paper presents explicit calculations demonstrating how information is preserved, he says.
Stojkovic’s new study, “Radiation from a Collapsing Object is Manifestly Unitary,” was published in Physical Review Letters, with University of Buffalo PhD student Anshul Saini as co-author.