What is Computation? (How) Does Nature Compute?
Transcript by Adrian German (who was one of the co-chairs of the conference and introduced Deutsch to the audience—the other conference chair being Hector Zenil).
So it seems we’re asking ourselves today “What is Computation?” and either “Does Nature Compute?” or “How Does Nature Compute?” And there’s an amazing fact that motivates both of these questions and indeed motivates every other foundational question about computation as well. It is this: if you take any physical variable whatsoever, for example “who is going to be the next president of the United States”, to take a topical example or, another one is “the mean temperature of the Earth’s atmosphere as a function of time” and ask how that variable depends on other variables, then the answer will always invariably be a computable function—or, if there’s quantum indeterminacy involved then the probability distribution function will be a computable function. This is because the laws of physics refer only to computable functions—either directly or via computable differential equations…
