Digital Physics

Digital physics is associated with the notion that physical reality itself consists of nothing but information, mathematics, simulation, computation, or geometry—also known as the computational metaphor, pancomputationalism, and the it from bit philosophy. Without that metaphysical premise, digital physics merely represents an arbitrary restriction on the kind of math to employ in physics. Specifically, for convenience it aims to exclude the continuum and problems involving infinities. While this restriction facilitates computation, there is no guarantee that it corresponds to reality. To make physical reality digital to facilitate computation is rather the tail wagging the dog. For the universe to be thus computable in principle would mean that it is somehow artificial rather than natural—made rather than found. It would be a product of definition, like a program. Moreover, though mathematics effectively describes and anticipates many features of the world, to assert that physical reality is reducible to mathematics (let alone to digital computation), is purely metaphysics. While dressed up in the latest technology, such notions as digital physics, the “mathematical universe”, or the notion that the world is a simulation or computation, simply harks back to the idealism of Plato and Pythagoras. It reflects the wide influence of the computer on modern life and thought. But it is no more plausible that physical reality corresponds to the technology of the 21st century than that it corresponds to the clocks and waterworks of the 18th century or the steam engines of the 19th! Information is a new catchword in science, likewise a product of modern technology. Its significance for physics arose first because the basic equation of communication theory resembles the basic equation of thermodynamics (“information” playing the role in one of “entropy” in the other). It has proven a useful concept in physics and in computation, as a non-material quantity divorced from its familiar connotation of conveying meaning. But to assert it as a fundamental new physical entity—even the basis of physics—is an essentially idealist move and a symptom of lingering dualism.