BLACK HOLE MIRROR: Researchers have assumed that if information could emerge from a black hole, it would take eons to do so. However, a new study finds that the turnaround in an older black hole could be more like a few seconds, which would make it more like an information mirror.
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Gravity's Engines
We’ve long understood black holes to be the points at which the universe as we know it comes to an end. Often billions of times more massive than the Sun, they...
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NEW ORLEANS—A new study hints that black holes might not be as good at keeping secrets as researchers have long thought. A pair of physicists has reexamined the time it would take for information (think: your iPhone's memory) to potentially escape from inside a black hole.
They find that the 1s and 0s of your address book could be recovered as quickly as 1,000 bits per second—far faster than previously expected. "The black hole really behaves like an information mirror," says physicist John Preskill of the California Institute of Technology in Pasadena.
The finding, presented here at a meeting of the American Physical Society, marks the latest attempt to come to grips with the fate of information that has crossed the black hole event horizon, a boundary beyond which even light cannot escape. There is no doubt, of course, that the ultradense singularity at the heart of a black hole would vaporize an iPhone. The question is whether there is any imaginable way to piece together its original state.
Physicist Stephen Hawking first broached the subject in the 1970s. He postulated that black holes would gradually evaporate by radiating particles (now called Hawking radiation) that had bubbled up from the vacuum around the event horizon. The radiation would be so scrambled, he argued, that when the black hole disappeared after many trillions of years, all the information about its contents would be lost. Other researchers insisted that the data might be imprinted on Hawking's particles, and even Hawking has changed his mind.
As in previous work, Preskill and physicist Patrick Hayden of McGill University in Montreal imagined two citizens of a hyperadvanced civilization, Alice and Bob. Alice wants to destroy some bits (technically, quantum bits that are 0 and 1 simultaneously) by throwing them into a black hole. Bob aims to recover them by gathering all the Hawking radiation from the black hole. Prior research had shown that if Alice dropped her bits into a relatively young black hole, Bob would have to collect the Hawking radiation for half the life of the black hole before being able to decode a single one of Alice's bits.
In the new study, Alice holds onto her bits until after the black hole has reached the halfway mark. Before her data dump, Bob managed to prepare some bits of his own that he entangled with Alice's, meaning they were linked instantaneously across any distance. Preskill reports that Bob could reconstruct Alice's bits by mixing the next few bits of Hawking radiation following the data dump with what he'd already collected, along with his own bits. "It might be a very difficult quantum computation to do the decoding," he says, but Bob would need only about 10 percent more Hawking particles than the number of bits that Alice had thrown in. A black hole the size of the sun would emit up to 1,000 Hawking particles per second, Hayden says.
The catch is that Alice's dumped bits would have to rapidly mix with the rest of the black hole, spreading their entanglement to the outgoing Hawking radiation that Bob collects. Current theories cannot predict the speed at which entanglement would spread across a black hole. Still, researchers are impressed by the novel application of quantum information theory. "I didn't think there was much else you could say about black holes without a quantum theory of gravity," says researcher Fotini Markopoulou of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario.
The effect comes perilously close to contradicting known rules of physics. After reconstructing Alice's bits, Bob could throw his copy into the black hole, where the two copies might run into one another. Such a meeting would violate the uncertainty principle of quantum mechanics because it would allow measurements of both the position and momentum of the identical quantum state. But the few-second delay between when Alice and Bob can dump their respective bits is just long enough, Preskill says, for her bits to be destroyed by the singularity.
Such a narrow escape appeals to Stanford University physicist Leonard Susskind, who explains that if Bob had to wait for half the lifetime of a black hole to extract his first bit, quantum mechanics would be safe by a curiously wide margin, in his view. "I like the idea," he says, "that the most dangerous experiment you can think of is right on the edge."
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Reply | Report Abuse | Link to thisBut etangled photons will they keep their entanglement inside the eventhorizon ?.
This might be likely and if so, it might explain more about blackholes (which we can now artificaly create at the LHC in europe)
Very cool. And what would be the physical implications of outwitting the uncertainty principle?
Reply | Report Abuse | Link to thisthis is a very confusing theory as i understand that nothing even at the speed of light can escape from a black hole, so how ca nsomething going as slow as dial up (extremely slow)
Reply | Report Abuse | Link to thiscan escape from the black hole.
If I understand black holes correctly, nothing even at the speed of light can escape from a black hole, so how would something going as slow as dial-up EVER escape from a black hole(scince dial-up is so darn slow).
Reply | Report Abuse | Link to thisThis is all moot anyway, since from our perspective as an outside observer, it would take an infinite amount of time for any particle to cross the event horizon. At the event horizon, time dilation effects due to the gravity would cause time to essentially stop for ANY observer outside the event horizon.
Reply | Report Abuse | Link to thisSo, for all practical purposes to ANY observer outside an event horizon, nothing will ever fall into an event horizon. In fact, the black hole itself will never actually form. The star's collapse, as viewed by ANY outside observer will continually slow, eventually stopping right at the moment the event horizon forms.
Hi folks. I reckon I should have explained something about Hawking radiation: It occurs when pairs of (entangled) particles form around the event horizon such that one of them lies inside the horizon and one lies outside. The inner particle is indeed trapped, but the other one isn't, and it's entangled with the one on its way to the singularity.
Reply | Report Abuse | Link to thisAfter having a discussion with my 14 year old son about how neither of us understands quantum physics, I saw a show where they discussed identical twins that seem to share experiences across long distances. For example one twin wakes up in the middle of the night with serious chest pain about the same time as the other was murdered via a stab wound to the chest.
Reply | Report Abuse | Link to thisIf these magic entangled bits can share state across the event horizon, can they also share state across comparetively short distances between two people on the same planet? Can entanglement occur in the womb? Would it last 30 years? Would it require so much energy that it would cook a human like a hotdog in a blast furnace?
I've always felt that most of the "new age" stuff was just perceptiveness preying upon ignorance. How long until the psychic fiends network advertises that they will "entangle our atoms" to predict our future and eliminate bad fortune?
"It is very interesting about Haqwking ahout the event horizon and also the annihilation of the particle.Might the annihilation leds to radiation .
Reply | Report Abuse | Link to thisHere's something that puzzles me about the current descriptions of Hawking radiation:
Reply | Report Abuse | Link to thisParticle pair-production creates two mirror-identical versions of a particle (a particle and its antiparticle), and in the p-p description of Hawking radiation, the hole swallows one of them and the other manages to escape.
Now, if HR emissions were truly random (as was originally suggested), one might expect the hole to emit equal quantities of matter and antimatter, and since these escaping particles would then tend to annihilate each other, we'd then have expected the HR emissions to consist of more light and less protons, electrons, etc.
But if the information encoded into HR emissions really originates with information that previously fell into the hole (the more recent view), and our region of universe favours matter over antimatter, and this bias is reflected in the mix of material that the hole has already eaten, then, if this “bias†information isn't lost, shouldn't the hole's emissions be biased towards matter rather than antimatter, too?
If the hole's HR emissions really are biased towards "normal" matter, then how do we model this using the p-p idea? Would we have to say that the p-p process is somehow polarised, so that when the pair is produced, the antimatter member of the pair tends to be on the side facing the hole, and is more likely to be eaten? What sort of mechanism might lead to this sort of polarisation?
Could Black Holes be the entrances to Hell?
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