Science friction

The Black Hole War

My Battle With Stephen Hawking to Make the World Safe for Quantum Mechanics

Leonard Susskind

Little, Brown: 480 pp., $27.99

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IN A PACKED lecture hall at Columbia University in 1958 -- or so the story goes -- the eminent physicist Wolfgang Pauli was presenting a radical new theory. In the audience was Niels Bohr, another eminent physicist, who, at lecture's end, stood up and announced: "We are all agreed that your theory is crazy. The question that divides us is whether it is crazy enough to have a chance of being correct."

"Crazy enough" is no doubt a thought that occurred to Stanford theoretical physicist Leonard Susskind when he came up with his holographic principle -- an idea that has recently gained traction in the physics community. The principle, which states that our universe is a three-dimensional projection of information stored in two dimensions at the boundary of space, certainly ranks as crazy. But is it crazy enough?

After reading Susskind's entertaining new book, "The Black Hole War," you may decide that, yes, the holographic principle may well be on the good side of crazy. But before he gets to the holographic principle, Susskind gives an explanation, both lucid and enjoyable, of why black holes are so crucial to the future of physics and to any eventual reconciliation of relativity and quantum mechanics.

Einstein's general theory of relativity describes the world of the very large: planets, stars, galaxies, black holes, the warped curvature of space. Quantum mechanics describes the world of the very small, the bizarre precincts of subatomic particles, where gravity is trivial. General relativity is "classical," in that it can be used to make definite predictions about reality. Quantum mechanics is not: One can predict outcomes only in terms of their probability. The dream of many physicists is to find a way to unify these two seemingly antagonistic conceptions of reality.

It turns out, though, that black holes may have just the right ingredients for a unification recipe. A black hole is a region of space at whose center is the remnant of a collapsed star. But "remnant" isn't really the right word: Because of intense gravitational pressure, that star has become what physicists call a singularity -- an infinitesimal point of infinite density. Black holes suck up everything in their vicinity; gravity in a black hole's interior is so strong that nothing can escape, not even light.