All is computation

The early history of science includes many examples of attempts to treat all aspects of the universe in a uniform way. Some were more successful than others. "All is fire" was never definite enough to lead to much, but "all is number" can be viewed as an antecedent to the whole application of mathematics to science, and "all is atoms" to the atomic theory of matter and quantum mechanics. My "all is computation" will, I believe, form the basis for a fruitful new direction in science. It should be pointed out, however, that it is wrong to think that once one has described everything as, say, computation, then there is nothing more to do. Indeed, the phenomenon of computational irreducibility discussed in this chapter specifically implies that in many cases irreducible work has to be done in order to find out how any particular system will behave.