BookEnds: Computing Takes Quantum Leap

Is reality simply the result of a complex computer program, constantly running and churning out all the events that make up the universe?

This isn’t the tagline for “The Matrix 3,” but rather the question proposed by MIT Professor Seth Lloyd ’82 in his new book, “Programming the Universe.”

Lloyd thinks that most physicists are missing the point: the story of the universe isn’t about particles and forces, but rather about information.

In an ordinary digital computer, information is registered as bits of stored electric charge, either 0 or 1, “yes” or “no.” Similarly, information is stored by the physical world in many ways, say in the speed and position of a particle.

Information of this sort is never lost; it only changes forms. When the cue ball strikes a billiard ball and stops, it becomes easier to describe the information content of the cue ball (all you need is its position), but you need to use more information to describe the other ball, which now has position and velocity. Likewise, each interaction between subatomic particles can create or exchange information.

According to Lloyd, these sorts of interactions are identical to the calculations that go on in a computer.

On a quantum scale, things become more confusing, and particles can register both 0 and 1 at the same time, or a little bit “no,” but mainly “yes,” and vice versa. This corresponds to the weird uncertainties associated with quantum mechanics, and turns out to be one of the important things that makes the world work.

More importantly, though, while it takes the most powerful digital computers to model even the simplest of quantum situations, a computer built specifically to take advantage of the multiple quantum states can do the calculation with ease.

Lloyd has been building quantum computers for years. So far, one of their most “impressive” achievements is factoring the number 15. Clearly, quantum computing has a long way to go.

However, the potential power is undeniable. Quantum computers calculate in the way that the world actually works, as opposed to the artificial “0 or 1” used in classical computers.

In this way, the world can be seen as simply a massive quantum computer, continuously computing itself.

Lloyd tackles these extremely confusing issues admirably, writing clearly and often humorously.

But I couldn’t help comparing his book to other paragons of popular physics–Stephen Hawking’s “A Brief History of Time” and Brian Greene’s “The Elegant Universe”—and Lloyd comes up short. His book is full of misleading statements—for instance, he writes that “...particles of sound are called phonons,” even though sound is almost never thought of as a particle—which, while correct on some level, are more likely to bewilder or misdirect the reader.

Lloyd’s metaphors, too, become tiresome by the end of the book (monkeys on typewriters make all too frequent appearances). I often felt like I was the monkey, and Lloyd was pulling the wool over my eyes.

Lloyd never tells me how a quantum computer really works: how do we make it, program it, and then get information out of it? He has spent years doing just that, but he doesn’t let us in on the secret.

The biggest (and most controversial) idea in Lloyd’s book may be his take on why the world is so complex. Admittedly more a metaphysical musing than hard science, Lloyd takes comfort in the idea that coherent information creates more coherent information and that our universe was programmed for order. Lloyd sees life and evolutionary complexity as almost deterministically guaranteed.

In an extremely poignant passage at the end of the book, Lloyd brings this down to a human scale, and says why it all matters for us.

In describing the death of his dear friend and mentor Heinz Pagels on a hiking trip, Lloyd sees information as the ultimate connection between all of us: “Heinz’s body and brain are gone...But we have not entirely lost him. While he lived, Heinz programmed his own piece of the universe. The resulting computation unfolds in us and around us...Heinz’s piece of the universal computation goes on.”

This comforting view is a lot more reassuring than Kubrick’s Hal ever was regarding the consequences of computational power.

—Look for more book reviews in Friday’s Arts section.