The universe as a computer?

Kenneth Silber writes about quantum mechanics and the role of information theory in physics. Among other topics, he addresses the computing power of the universe as a whole.

Lloyd has performed calculations regarding the physical world's capacity for information processing. He notes, for instance, that "the ultimate laptop" (a collection of matter the size of a laptop computer, but in which every particle is utilized for computing) could store more information than all the hard drives now existing. Moreover, he has run such numbers for the observable universe as a whole. By Lloyd's calculations, this cosmic computational capacity equals 10¹²² operations on 10⁹² bits of information.

These figures can be interpreted several ways: as an upper limit to how much computing could have been done in the universe; as a lower limit to what would be required to simulate the universe; or, as an actual description of what the universe has done. Whether one regards a physical system as a computer, Lloyd notes, is somewhat subjective, and in his view it is useful to consider the universe to be a giant quantum computer. Such an approach, he believes, will generate new insights into physics, including on the highly difficult problem of reconciling quantum mechanics and general relativity.

Of course, as soon as we hear the universe being compared to a computer, the Intelligent Design / Intelligent Origin Theorists will start making noise.

The universe-as-computer concept may also play into the current strife about intelligent design. It might be argued that a computer implies a programmer. However, this may be taking the analogy too far. What the universe is computing, in Lloyd's picture, is not some external output but rather its own behavior. And a very large portion of its computing power seems to be tied up in such behavior as random collisions of atoms.

Indeed, Lloyd's argument may be disturbing to intelligent-design proponents, in that it suggests how complexity can arise from an underlying randomness. In Lloyd's favored analogy, monkeys typing on typewriters produce gibberish — but monkeys typing on computers can produce simple code that would generate a wide variety of outputs.