New Idea Could Solve Black Hole Information Mystery

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Physicists have come up with a way to explain how information could escape from a black hole, an idea that's been debated since the 1970s.

But the new proposal leaves the long-held concept of a space-time continuum in tatters.

Whether you've been following the arguments over the years or not, now might be a good time to reach for some aspirin, as space-time continuum textbooks may have to be revised.

First, some basics: Black holes are like kitchen sinks. Stuff is only supposed to go one direction, and then it's gone forever, lost to the formidable clutches of gravity in a bizarre distortion of space and time, or what scientists call space-time. You no longer have to be an Einstein to have heard as much, though all this is indeed based on his work.

However, in the 1970s, Stephen Hawking declared that black holes leak. Eventually, like a tire doing a slow, inaudible pffffft, everything that was sucked in would seep out. But, and this was a big but that Hawking proposed, any information that went into the black hole would be lost. Whatever stuff leaked out, in other words, would not be identifiable as corresponding ingoing stuff.

Oops!

But by the late 1990s, Hawking's idea fell out of favor. It messed too much with quantum mechanics, a successful theory that says information can't be lost.

In 2004, Hawking renounced his idea.

Yet no viable explanation has emerged, until perhaps now, for how the information could get out of the black hole.

The newly proposed scheme, in a nutshell, says space-time is bigger than was thought, and so there's room for the information to reappear.

"Information only appears to be lost because we have been looking at a restricted part of the true quantum-mechanical space-time," said Penn State's Abhay Ashtekar, who has come up with the idea. "Once you consider quantum gravity, then space-time becomes much larger and there is room for information to reappear in the distant future on the other side of what was first thought to be the end of space-time."

While this might not explain where your socks are, it does come with some mind-bending new concepts for theorists to chew on.

For starters, Ashtekar thinks space-time is not a continuum, as we've been hearing for years. Rather, "it is made up of individual building blocks," according to a statement released by the university. It's like a piece of fabric which, "though it appears to be continuous, is made up of individual threads."

Now what?

The space-time continuum has long been invoked to understand how things get warped in the presence of gravity. For example, light from the sun is bent slightly as it passes Earth, thus changing the timing and perceived origin of that light as witnessed by someone farther out in the solar system. The effect in this example would be miniscule, but not imperceptible. One study found that satellites were dragged by about 6 feet (2 meters) every year because our world's gravity, combined with its spin, mucks with the cosmic fabric.

Light traveling near a black hole is bent so severely that it's consumed, never to be seen again (excepting that whole leaking thing). Such a distortion in the space-time continuum, hard as it might be to comprehend, is the basis for other exotic notions such as time travel. A person who wants to go to another dimension, the thinking goes, need only to enter a severely warped reality, called a singularity, and somehow emerge unharmed on some other side.

"Once we realized that the notion of space-time as a continuum is only an approximation of reality, it became clear to us that singularities are merely artifacts of our insistence that space-time should be described as a continuum," Ashtekar said.

The mind-bending proposal will be detailed in the May 20 issue of the journal Physical Review Letters. It was funded by the National Science Foundation and the Penn State Eberly College of Science. Victor Taveras, a graduate student in the Penn State Department of Physics, and Madhavan Varadarajan, a professor at the Raman Research Institute in India, contributed.