Secrets of the cosmos

Could the universe be a giant computer? A new book argues just that, and unlocks some great scientific mysteries along the way.

By Laura Miller

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March 6, 2006 | The universe might just be an enormous computer -- that's the final, mind-twisting pirouette at the conclusion of Charles Seife's new book about information theory and quantum computing, "Decoding the Universe: How the New Science of Information Is Explaining Everything in the Cosmos, From Our Brains to Black Holes." By the time you get to this suggestion, the statement seems pretty plausible, but by then you've already traveled through Seife's crystal-clear explications of thermodynamics, relativity, quantum mechanics, black holes and multiple universes. In other words, you know he's not talking about using the cosmos to search the Web during your lunch break for the best price on iPods.

Every reader has his or her own reasons for plunging into a book like "Decoding the Universe." The sizable audience for popular science writing is mostly made up of former science and math majors who find the material congenial and like to keep up with the theoretical fringes of the subjects they once studied. People with specialized expertise like to see how their field is being represented to the public. Those who know the discipline might even prefer Seth Lloyd's new book, "Programming the Universe: A Quantum Computer Scientist Takes On the Cosmos," since Lloyd is a bona fide MIT professor while Seife is a journalist. (Seife uses one of Lloyd's thought experiments -- in which he designed the "ultimate laptop" out of a black hole -- as an example in "Decoding the Universe.")

Still, for the former liberal arts major and other right-brainers, Seife is the man; his lucid metaphors and unfussy descriptions (along with Matt Zimet's fine illustrations) offer exceptionally solid footholds in some of the most bizarre and counterintuitive realms of physics. Why venture into such challenging territory? Because puzzling out this kind of thing helps keep you from getting senile. Because before blithely writing off scientists as rigid and uncreative you should get a glimpse of how the other half thinks. Because this is a great way to have your mind well and truly blown without all the wishful folderol of, say, Carlos Castaneda, intelligent design and "What the Bleep Do We Know!?" And because the cosmos is a truly strange and fascinating place even without all that folderol, so why not get to know it better?

For me, though, the reason was that darn cat -- Schrvdinger's Cat, to be precise. This famous theoretical feline is inside a box and is both alive and dead until someone decides to open the box and find out which is the case. I've always found the cat's situation profoundly baffling and more than a little silly, so it's cheering to learn that Erwin Schrvdinger thought so, too; this particular thought experiment was devised in 1935 by the Austrian physicist to point out, in Seife's words, "how stupid" the quantum concept of "superposition" was (even though Schrvdinger himself was partly responsible for establishing it).

It would be hard to improve upon Seife's elucidation of Schrvdinger's thought experiment, but in brief: The box contains both the cat and a vial of poisonous gas connected to a device outside the box. When triggered, the device will break the vial and kill the cat. The device is triggered when a "quantum object," say an electron, hits it. An electron is fired at the device but it hits a beam splitter first, and the splitter causes the electron to go in one direction -- toward the device, thereby killing the cat -- or another -- away from the device, leaving the cat alive.

However, experiments have shown that under the right conditions, a tiny object like this electron, when it hits a beam splitter, enters the weird state known as "superposition." It goes in both directions, even though the directions are mutually exclusive. Only when someone or something attempts to observe the electron and figure out which way it has gone does the superposition "collapse" and the electron seemingly "chooses" one direction or the other. Until it's measured, though, the electron hits the device and it does not hit the device. The cat is killed and it is alive. Theoretically, the superposition of the electron is transferred to the cat, which is both alive and dead until someone tries to figure out which by opening the box. And everyone (including Schrvdinger) knows that's ridiculous.

There's no shortage of explanations of the Schrvdinger's Cat paradox laid out for a popular audience, but Seife's, nestled in the context of a larger discussion of the conflicts among quantum and classical physics and relativity, is one of the most effective I've encountered. So is his explanation of "decoherence," the principle that explains why the conditions that prevail with a tiny, simple object like the superposed electron don't prevail with a big, complicated object like a cat.

The key to understanding how all these odd principles work, according to Seife, is the relatively new field of information theory. And the hardest thing to grasp about this theory is the fact that "Information is physical. Information is not just an abstract concept, and it is not just facts or figures, dates or names. It is a concrete property of matter and energy which is quantifiable and measurable. It is every bit as real as the weight of a chunk of lead or the energy stored in an atomic warhead, and just like mass and energy, information is subject to a set of physical laws that dictate how it can behave."

Seife is right, this is hard to grasp, partly because in ordinary conversation we use the word "information" to describe things that feel abstract and immaterial to us. But, as Seife explains, information has to be transmitted somehow, through some physically detectable medium (the air in the case of sound; ink and paper in the case of writing, to list only our most familiar methods), and it turns out that the process of transmitting it always uses up some energy.

I was contemplating this the other day while using a candy thermometer to figure out if the sugar syrup I was boiling had become hot enough to add to a bowl of whipped egg whites. Reading the numbers on the thermometer might seem to the casual eye like a nonphysical transmission of information, even though energy from the electric company was used to generate the light bouncing off the thermometer and into my eyes and energy from my lunch powered the neurons that fired in my brain as I read it.

But what intrigued me most about the experience was the realization that while "240 degrees" was the information I thought I was getting from the thermometer, it was really the mercury in the device that told me what I needed to know. It borrowed a little heat from the boiling syrup and expanded up the glass tube of the thermometer to give me the news. The increase in the temperature and the volume of that mercury was the true source of the information (about the heat of the syrup). My seven-minute frosting was a classic illustration of information in action!

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