Rip up a piece of paper , and you can piece it back together . Burn a book , and you could theoretically do the same . But send information into a black hole , and it 's lost forever – or at least that 's what many physicists have been arguing for nearly half a decade . Now , one scientist says this may not be true , and that interactions between particles emitted by a black hole can reveal information about what lies within . For nearly 40 years , physicists have argued that black holes suck in information and then evaporate without leaving behind any clues as to what they once contained . Now , one scientist says this may not be true . 'According to our work , information is n't lost once it enters a black hole , ' says Dejan Stojkovic , an associate professor of physics at the University at Buffalo . 'It does n't just disappear . ' His new paper presents explicit calculations demonstrating how information is preserved , he says . This is an important discovery because even physicists who believed information remains in black holes have struggled to show , mathematically , how this happens . The research marks a significant step toward solving the 'information loss paradox , ' a problem that has plagued physics for almost 40 years , says Dr Stojkovic . The paradox posed a huge challenge for the field of physics because it meant that information inside a black hole could be permanently lost when the black hole disappeared . Last year , Hawking revised his theory by declaring that black holes were in fact 'grey ' . The grey hole theory would allow matter and energy to be held for a period of time before being released back into space . In the 1970s , Stephen Hawking proposed that black holes were capable of radiating particles , and that the energy lost through this process would cause the black holes to shrink and eventually disappear . But last year , Hawking revised his theory by declaring that black holes were in fact 'grey ' The grey hole theory would allow matter and energy to be held for a period of time before being released back into space . He says that the idea of an event horizon , from which light can not escape , is flawed . He suggests that instead light rays attempting to rush away from the black hole ’ s core will be held as though stuck on a treadmill and that they can slowly shrink by spewing out radiation . Hawking told the journal Nature : 'There is no escape from a black hole in classical theory . [ But quantum theory ] enables energy and information to escape from a black hole ' . A full explanation of the process , Hawking admits , would require a theory that successfully merges gravity with the other fundamental forces of nature . This is a violation of quantum mechanics , which states that information must be conserved . In the 1970s , Stephen Hawking proposed that black holes were capable of radiating particles , and that the energy lost through this process would cause the black holes to shrink and eventually disappear . But last year , Hawking revised his theory by declaring that black holes were in fact 'grey ' The grey hole theory would allow matter and energy to be held for a period of time before being released back into space . How exactly it 's possible to recover information from a black hole has remained a topic of debate . Instead of looking only at the particles a black hole emits , the latest study also takes into account the subtle interactions between the particles . Interactions between particles can range from gravitational attraction to the exchange of mediators like photons between particles . Such 'correlations ' have long been known to exist , but many scientists discounted them as unimportant in the past . 'These correlations were often ignored in related calculations since they were thought to be small and not capable of making a significant difference , ' Stojkovic says . 'Our explicit calculations show that though the correlations start off very small , they grow in time and become large enough to change the outcome . '
Comments made by physicist Dejan Stojkovic from the theory of Buffalo . He believes clues to contents lie in interactions between particles emitted . Quantum theory states that information is always relevant . It backs up Stephen ##man 's assertion that black holes are ' invisible '