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!
Of course, once I took the thermometer out of the syrup the mercury began to cool down and contract down the glass tube. Was the information lost? Not really. The heat from the mercury dispersed into the air in my kitchen. As Seife explains, with sufficiently sensitive instruments I would have been able to detect the difference in the air and from that gather information about the changing temperature of the mercury just as the mercury detected the temperature of the syrup. The information was still there, just dissipated to the point that I couldn't find it.
The cosmos, as Seife depicts it, is a great big information swap meet. Objects enormous and minuscule are always encountering other objects and being affected by them in such a way that they "gather information" -- not consciously, of course, but in the way that the mercury collected information about my boiling syrup. A pool ball that's hit by another pool ball receives information about the speed and direction of the ball that hit it. Subatomic particles do the same. Of course, subatomic particles do a lot of things that are much more baffling than this, like existing in two different places at the same time until someone or something tries to locate them. But, as Seife argues, information still lies at the root of all this. "Decoding the Universe" offers a history of the development of information theory, too, beginning with the cryptographers of World War II. Many of these men were mathematicians who applied themselves to the problem of reducing information to its essentials so that in its encoded form it would be harder to crack. In the 1940s, an electrical engineer and mathematician, Claude Elwood Shannon, working for Bell Labs trying to figure out how much information a copper phone line could carry, developed a mathematical theory of communication. He introduced the term "bit" for the smallest unit of information -- it's either one thing or another, on or off, 1 or 0 -- and became the father of information theory.
Vast cathedrals of information can be built from the humble bit -- as the computer you're reading this on demonstrates all the time. But it also turns out that each medium -- copper wires or fiber optic cables or digital circuits or printed pages -- has a limit to the number of bits, and therefore the amount of information, it can transmit. Information, as Seife takes frequent pains to remind his readers, is a physical property. You can measure it and the capacity of any medium to carry it.
Seife goes on to explain how information functions in the peculiar realms of the very fast and the very small, where the seemingly rock-solid laws that govern classical physics start to bend and warp. There's the thought experiment about a man carrying a 15-meter-long spear through a 15-meter-long shed who, because he's running so fast -- at 80 percent of the speed of light -- either can or can't fit the whole spear in the shed, depending on how you look at it. If you're perched in the rafters of the shed (and therefore stationary), the spear is only 9 meters long, but if you're riding on the runner's shoulders and traveling at his speed, it's the shed that's shrunk to 9 meters. The different measurements are all correct and, furthermore, predictable according to the laws of relativity. But, as Seife points out, these laws (and their paradoxes) tell us about changes in measurement -- measurements of how long the shed is and how much time it takes the man to sprint through it -- and so they, too, are essentially about information.
The fundamental structure of information -- bits set to one of two alternatives -- means that all kinds of things can be used to "store" information: one lantern in the church steeple if the British are coming by land or two if by sea, and so on. Very small objects can also be used to store and process information, and so, it turns out, can the bizarre tiny objects of quantum mechanics.
The gnarliest concepts described in "Decoding the Universe" -- entropy, superposition, decoherence -- have to do with probability. Entropy (which as Seife points out has nothing to do with how messy your room is) is really "the measure of the improbability of the arrangement of stuff inside a container." The more stuff there is, the more likely that it will be distributed more or less evenly and randomly, and all the stuff in the universe is moving toward just that state. Seife warns his readers about this gloomy inevitability right from the start (the first line of the book is "Civilization is doomed"), but by the time you get to his final announcement that at some unimaginably distant future time the cosmos will be uniformly "dark" and "lifeless," you understand that this moment is so far away that, given the capacity of human understanding, it might as well be never.
Before we get there, though, we'll surely have figured out quantum computing, the kind of information processing that goes on when you work with "qubits" rather than old-fashioned bits. Quantum computing takes advantage of the principle of superposition -- the same thing that made Schrvdinger's theoretical cat both alive and dead -- to create bits that are not on or off, 1 or 0, but something more like 50 percent likely to be on or 25 percent likely to be off. To use Seife's example, this is a lot like being able to try four keys in one lock at the same time. It makes for much faster information processing; as Seife explains, "a number that might take a classical computer the entire lifetime of the universe to factor might take a quantum computer only a few minutes." The uncanny paradoxes of quantum computing have recently led to a group of scientists at the University of Illinois at Urbana-Champaign demonstrating the first example of "counterfactual computing," in which they got an answer from their quantum computer without running it!
Of course, information isn't the same thing for a physicist or mathematician that it is for most of us. Seife ruefully points out that the 70,000-odd words of "Decoding the Universe" contain "less than two million bits of information," the same amount as 11 seconds of a track from a Britney Spears CD or two and a half seconds of the movie "Dumb and Dumber." No other passage in the book better demonstrates the trickiness of illuminating information theory to the general reader; we can see that "Decoding the Universe" contains what seems like abundant information about the fundamental nature of existence, while most of us would view the Britney clip as pretty empty.
Bits can measure information in its raw, physical form -- the exact color of each one of tens of thousands of screen pixels, the precise duration of Britney's E-flat wail. What they can't measure, however, is the value placed on the information by those who receive it. What they can't measure (yet?) is meaning. And meaning is something that "Decoding the Universe" has in abundance.