| Its harsh to say it, but Wolfram tried his best at a computational theory of everything and failed. We didn't know this is in the eighties, when the first cellular automata ideas were conceived. So it was a worthy thing to explore in earnest. But it did not work. There is nothing to show for it. It did not strike a vein. These things happen. All the time. You have a great startup idea but no market fit. In this case the market is the Universe. And you cant fake it till you make it with the Universe. The universe most certainly has a mysterious affinity with mathematics. And computation is a mathematical concept. So its a decent hypothesis. But there are a lot of mathematical concepts that dont manifest in any shape or form in physical reality. From the simple geometric thinking of ancient cultures to Newton's and Leibnitz's calculus and then all the subsequent glories of 19th and 20th century physical theory, when new mathematical concepts "fit" the way the universe works there is just an avalanche of prediction, verification, learning, refinement, further prediction etc. Its wrong to think we have reached the end of "mathematical physics". So new ideas are needed, and computation is as good an inspiration as a falling apple. But prunning dead-end ideas is a faster way to get closer to the truth. |
It's extremely easy to come up with models that reproduce most of modern physics if you at all know what you're doing. String theory does it, loop quantum gravity does, and so on. There are deterministic models that avoid the "God playing dice" aspects of quantum mechanics yet still reproduce all the classic results. There are rods + gears models of electromagnetism that give the right numbers even though the mechanisms are ludicrous.
The fact that it is so easy to come up with models that match modern physics is in itself a meaningful and not at all obvious thing, but it ultimately derives from the fact that the real universe seems to operate on laws that spring directly from symmetry principles. It turns out that most of the physics that matters is extremely "natural" and can be derived as a consequence of much simpler assumptions than you'd expect, even if the math that gets you from those assumptions to the resulting mechanics can be intense. If you're unfamiliar with this concept but understand calculus, you owe yourself a very deep dive on Noether's theorem, the way that symmetry radiates into every aspect of physics is one of the most profound things to study in physics.
The upshot of Noether's theorem and the ubiquity of its applications in modern physics is that it's very easy to create a theory that matches the predictions of e.g. special relativity: you just need to sneak it in by, for instance, defining your "foliations" in such a way that you have Lorentz symmetry, then everything else comes for free. If you want general relativity, then you (mostly) just need invariance under diffeomorphisms, which is really frickin easy to build into the limit of any graph-based model since you're basically redefining space altogether. I still don't entirely understand how Wolfram gets quantum theory in there; I don't doubt that his model does actually do it at a mathematical level, I just can't stand the verbose writing style and have too little interest in his particular theory to work through it, but once you start talking about constantly branching and recombining state graphs and stuff like that it's not at all hard to imagine that you could pick your definitions in such a way that Hilbert spaces pop out and then you define observers/observations in a way that makes it cleanly match a many-worlds interpretation of quantum mechanics.
But the fact that you have a model that reproduces all of known physics doesn't mean anything. We already have several of those. And people rightly criticize even the top contenders on the basis that they all tend to suffer from the same defect, they're overparameterized and could predict a lot of universes that don't work the way ours does, and there are very few experiments that would rule the models out altogether (rather than merely constrain the parameters). To the extent that their predictions differ from what current theory would predict, their parameters could be easily tuned to match almost any result, which makes it tough to have any faith that the goalposts wouldn't be moved when results did come in that could test, say, the extreme conditions where quantum gravity would be relevant. Wolfram's is no different, except that as far as I can tell he hasn't gone anywhere near as far as e.g. the string theorists in working out what the different predictions would even be for his theory. He's just blindly declaring it correct.
Models are great, and I think there is something useful in Wolfram going down the rabbit hole in terms of showing what a model that reproduces quantum effects looks like, I feel like that is underexplored (the rules of quantum mechanics are usually taken as a given, even in theories of "everything"). But his breathless declarations of having solved physics are ludicrous, and I feel like his ideas might actually be taken much more seriously if he had a more realistic understanding of what he was working with.