There is some sort of relationship between computation and physics. Everyone takes for granted that it's possible to use computers to simulate the weather, but this is an incredible, nontrivial fact. Why is this possible? One unsatisfying answer is that the physical world is mathematical, and computers can evaluate certain mathematical expressions, thus computers can simulate physics. I don't think this answer is meaningful, because computation and math are so closely connected as to be nearly the same thing; in fact, there is a [well-known isomorphism](https://en.wikipedia.org/wiki/Curry%E2%80%93Howard_correspondence) between certain kinds of mathematical logic and computer programs. We can easily generalize the question to invalidate this response: why do logical systems like math and computation model the physical world so well? Another answer is that the physical world is fundamentally computational; at the most basic level, the true laws of physics are computer programs. David Deutsch states this idea, which is sometimes called the *extended* or *strong* *Church-Turing thesis*, as follows: > Every finitely realizable physical system can be perfectly simulated by a universal model computing machine operating by finite means. This thesis has little currency in modern physics, but I support it wholly. It implies that the ultimate physical laws will be written in terms of some formal [[Models of computation|model of computation]]; for example, as lambda expressions or as the state diagram of a Turing machine. It further implies that real numbers and continuity are no more than approximations, as Turing machines can only manipulate numbers of finite precision within a bounded amount of time. Related reading: - [Quantum theory, the Church–Turing principle and the universal quantum computer](https://royalsocietypublishing.org/doi/10.1098/rspa.1985.0070) by David Deutsch - [Interesting problems: The Church-Turing-Deutsch Principle](https://michaelnielsen.org/blog/interesting-problems-the-church-turing-deutsch-principle/) by Michael Nielsen - [The Unreasonable Effectiveness of Mathematics in the Natural Sciences](https://www.maths.ed.ac.uk/~v1ranick/papers/wigner.pdf) by Eugene Wigner