BRIAN GREENE Now, holograms are something we're all familiar with from the security symbol you find on most credit cards, but the universe as a hologram? That's one of the most drastic revisions to our picture of space and reality ever proposed. And the evidence for it comes from some of the strangest realms of space: black holes.

LEONARD SUSSKIND This is a real disconnect, and it's very hard to get your head around: modern ideas, coming from black holes, tell us that reality is two-dimensional, that the three-dimensional world, the full-bodied three-dimensional world, is a kind of image of a hologram on the boundary on the region of space.

S. JAMES GATES, JR. This is a very strange thing. When I was a younger physicist I would have thought any physicist who said that was absolutely crazy.

BRIAN GREENE Here's a way to think about this. Imagine I took my wallet and threw it into a black hole. What would happen? We used to think that since nothing, not even light, can escape the immense gravity of a black hole, my wallet would be lost forever, but it now seems that may not be the whole story.

Recently, scientists exploring the math describing black holes made a curious discovery. Even as my wallet disappears into the black hole, a copy of all the information it contains seems to get smeared out and stored on the surface of the black hole, in much the same way that information is stored in a computer.

So in the end, my wallet exists in two places: there's a three-dimensional version that's lost forever inside the hole black and a two-dimensional version that remains on the surface as information.

CLIFFORD JOHNSON (University of Southern California) The information content of all the stuff that fell into that black hole can be expressed entirely in terms of just the outside of the black hole. The idea, then, is that you can capture what's going on inside the black hole by referring only to the outside.

BRIAN GREENE And, in theory, I could use the information on the outside of the black hole to reconstruct my wallet.

And here's the truly mind-blowing part: space within a black hole plays by same rules as space outside a black hole or anywhere else. So if an object inside a black hole can be described by information on the black hole's surface, then it might be that everything in the universe, from galaxies and stars, to you and me, even space itself, is just a projection of information stored on some distant two-dimensional surface that surrounds us.

In other words, what we experience as reality may be something like a hologram.

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