Do the laws of physics emerge from the laws of information? Perhaps, according to two World Science Festival events I attended this weekend on the connection between computers and the cosmos. The first examined the insight that all the information about a three-dimensional world can be encoded onto a two-dimensional surface. Taking this notion to the extreme, we might imagine that the 3D world we inhabit is only a projection from a deeper reality, an ephemeral hologram that leaps off some cosmic film.
The second event considered whether information is itself the foundation upon which all else rests, the true firmament of the cosmos, deeper than atoms, quarks or even space-time itself.
As might be expected from mere 90-minute discussions, the events, though fascinating, left me thirsty for more. Here is a brief collection of outside reading for those of you who might feel the same way.
In 2003, Jacob Bekenstein wrote a feature for Scientific American called "Information in the Holographic Universe" (subscription required), which provides an excellent popular-level account of the notion that the entire universe might emerge from a two-dimensional surface. (The work builds on the 1997 article "Black Holes and the Information Paradox" [PDF link] by Leonard Susskind.) Beckenstein’s article really helped me to understand how two superficially distinct forms of entropy—thermodynamic entropy and information entropy—are in fact equivalent. My colleague George Musser also wrote a good post on this subject a few weeks ago as a preview to the World Science Festival event.
The idea that the universe is itself a computer—or, more suggestively, that the computer is the universe—extends back almost to the dawn of the information age. The German computer scientist Konrad Zuse was the first to suggest that the universe is being computed on a universal computer in Rechnender Raum, which was first published in 1969 [PDF link to English translation]. It was an idea ahead of its time. At the WSF event, Jürgen Schmidhuber, a professor of artificial intelligence at the University of Lugano in Switzerland (and intellectual descendant of Zuse’s) noted that after the publication of Rechender Raum, everyone thought that Zuse—who had already achieved legendary status in the computer science community for constructing one of the world’s first programmable computers, the Z1—had gone and lost his mind.
Yet the idea lived on, most notably in the work of Edward Fredkin, a polymath computer scientist who was also present on the panel. He was one of the three scientists profiled by Robert Wright in his book Three Scientists and Their Gods: Looking for Meaning in an Age of Information; the chapter on Fredkin and his ideas was excerpted in the Atlantic Monthly as "Did the Universe Just Happen?"
It took the legendary physicist John A. Wheeler to really bring the idea to prominence within the physics community. He coined the pithy summation it from bit, and laid out a research program to investigate the connection in his 1989 essay "Information, Physics, Quantum: The Search for Links."
In recent years the most prominent proponent of the digital universe viewpoint has been the mathematician and entrepeneur Stephen Wolfram, who argued in his 2002 book A New Kind of Science that simple programs underlie all natural phenomena. Scientists have been critical of Wolfram’s book—in some cases blisteringly so—at least in part because he ignores all the work on the topic that had come before him and implies that he is solely responsible for whatever insights might emerge out of the digital physics program. The physicist Steven Weinberg wrote an illuminating review of A New Kind of Science for the New York Review of Books, concluding that "I don’t think that his book comes close to meeting his goals or justifying his claims, but if it is a failure it is an interesting one."
Well, that’s all I’ve been able to digest in a few days. What am I missing? Where should I go next? Please include your suggestions in the comments.