Cosmologists Discover How Black Holes Can Leak

Extra dimensions should allow information to escape from black holes, according to a new model of cosmology

Technology Review, KFC 12/23/2010

Black holes are relatively straightforward to imagine. They are regions of space in which gravity is so strong that even light cannot escape.

The conventional view is that if you were ever unlucky enough to fall into a black hole, nothing could get you out. Not even information about you could escape.

That view may have to change thanks to an interesting new approach by Valeri Frolov at the University of Alberta in Canada and Shinji Mukohyama at the University of Tokyo in Japan. Their idea also suggests a novel solution to one of the enduring paradoxes associated with black holes: what happens to information that enters such a region of space.

Frolov and Mukohyama start by thinking about our 4 dimensional universe embedded in some kind of higher dimensional space. That's a familiar approach to many cosmologists who have been toying with properties of this kind of multidimensional cosmos for at least a decade. In the language of cosmology, our universe is a "brane" embedded in higher dimensional space.

Frolov and Mukohyama then go on to think about geodesics in these spaces, the shortest distances between two points. They point out that it's quite possible that the shortest distance between two points in our 4-dimensional space may not correspond with a geodesic in a higher dimensional space.

In other words, the extra dimensions may offer a shortcut from one part of our universe to another. And although it wouldn't be possible for a conventional physical object to follow this path, information could make the trip.

That has important implications inside a black hole, they say. Although there would be no route out of a black hole in the 4D brane, Frolov and Mukohyama say it ought to be possible for information to leak out through this shortcut into higher dimensional space and then back to ours. They call this breach in higher dimensional space a brane hole.

That could help solve an old problem. One of the big puzzles in black hole physics is what happens to information once it enters a black hole. The conventional view is that information cannot be destroyed and so must be recovered somehow. Cosmologists have come up with various suggestions for how this might happen but it's fair to say that they are still scratching their heads hard over this.

Frolov and Mukohyama's suggestion will give them something else to think about.

Of course, critics will point to other exotic effects that their model predicts. Shortcuts through space, if only for information, make possible all kinds of counterintuitive shenanigans. As Frolov and Mukohyama point out: "An observer on the brane would describe this situation by saying that the extra dimensions provide a channel of information exchange with an effective superluminal velocity."

In other words, these shortcuts would allow faster-than-light communication and all the paradoxical behaviour that goes with it. Bizarre!

Ref: http://arxiv.org/abs/1012.4541 :Brane Holes