Earlier quoted context omitted.
Literally, i.e. the fabric of space-time. Then particles and energy are patterns in the graph -- that we can describe useful physics in terms of the graph, but that the graph just is, it's not a description or approximation of something deeper. Unless there's a semantic difference you're getting at that I'm not aware of?
Interesting concept, but I fail to see how it can model the whole universe. Describing it, maybe, but the universe being a graph, well for a start, what is the graph made of? Is it "material" is it "information"?
The Wolfram Physics Project
291–300 of 342 posts
Re: The Wolfram Physics Project
#292After a few iterations, I think I understand the point of this piece. It was a bit difficult to hone in on, though. The article suggests that working out the theory of something like rule production systems, and then figuring out how that theory relates to existing insights from physics, is the best path toward a Fundamental Theory of Physics. My primary source of skepticism stems from the fact that the theory of rul…
Have ideas from computer science had significant reach inside theoretical physics before? It seems like physics has only recently discovered its love-affair with information theory, but information theory had existed for a long time before quantum information theory became a hot area of study. Maybe what's new here are not the ideas themselves, but bringing them into an area of study that hasn't payed attention to th…
> Everything in physics and physical reality must have a digital informational representation.
Re: The Wolfram Physics Project
#293Earlier quoted context omitted.
>[4] Why just one rule? Is a specific combination of rules not itself a rule? A lot of descriptions of Conway's Game of Life describe it as multiple rules, and other places refer to its whole setup as a "rule". Rule 30 is sometimes called a "rule set". I don't think there's a strict difference between a rule set and a rule, though the simpler rule(set) the better seems to be easy to agree on. ... >(5) I would direct…
> I don't think there's a strict difference between a rule set and a rule Okay then. Why just one rule or rule set? I meant as much when I wrote what I wrote. Why a tiny/simple initial starting state and one rule (or rule set). Sure, simple elegant formal systems are enticing to our brains but why assume that of our universe? Why not even try to explain why you feel this to be true? It's a pretty huge assumption in m…
Honestly, I think this is a great way of describing what they're trying to do. I guess I think it's a little more realistic than you do: if our universe's physics could be described by a program on the order of tens of bits (I give an argument below for why we could expect that), then it's possible for us to come up with something like it from scratch by trying to construct a simple program that could have rich dynamics. If someone came up with a tiny model that happened to have physics emerge in it resembling our own, I'd be really interested to see how much we could learn from the model. They're trying to show that they happened to bump into interesting parts of relativity and quantum mechanics.
If they really did bump into relativity and QM from a simple system, then I think this is significant enough for more attention, even if they don't have any testable results yet, because it's possible that testable results will come from it. It might be that this model deeply resembles reality and we can flesh it out further, or it might just be that there is a class of models (that includes our physics) where relativity+QM arises (but not the rest of our physics, like the standard model), and we can learn about relativity and QM by studying models where the pair of them arise. Investigating this model is hard and it makes sense they want help.
> Sure, simple elegant formal systems are enticing to our brains but why assume that of our universe? Why not even try to explain why you feel this to be true? It's a pretty huge assumption in my eyes.
>Yes, and with good reason. Because TOEs claim to be fundamental – how can they be fundamental if there's something underneath them so to speak.
I've always imagined (and given the article's talk about "rule space", I think what Wolfram believes is something roughly similar) that the true-root TOE looks like the mathematical universe hypothesis / UDASSA (http://fennetic.net/irc/finney.org/~hal/udassa/) where in some sense, every possible computation exists, and they have measure (~the probability we find ourselves in it) inversely related to the length of information describing the computation (because if every possible computation existed, then every finite-length program would be instantiated infinite times by equivalent infinite-length programs with lots of ignored garbage code, and shorter programs would be instantiated proportionately more often).
From that, you would expect at large probability that our own universe's physics is described by the shortest possible program/rules that gives dynamics as rich as we see. If we imagined some universal computational language, it seems like specific cellular automata and hypergraph-rewrite systems could maybe be specified in tens of bits, so they're prime candidates for exploring. Even if those systems specifically aren't how reality works, then if they can produce dynamics about as rich as reality, then it implies that our reality's rules might be even shorter (or else we'd be more likely to exist in a cellular automata or hypergraph-rewriting system). At such short program lengths, the strategy of guess-and-check could be realistic, though the check part is really hard since we can't directly compute a significant number of timesteps, and instead have to try to reason about what large-scale patterns must emerge from the program.
(Wolfram specifically seems to believe that the hypergraph-rewriting system is universal enough to fill the role of the universal computational language, but I don't think that's strictly critical. As long as it's sufficiently simple to represent in whatever the root-TOE computes by, then it could be a candidate for our universe's physics. Hmm, I guess it would make sense that the way the root-TOE computes would have structure in common with whatever our universe's physics program is, because then our universe's program could be specified with fewer bits.)
Re: The Wolfram Physics Project
#294Earlier quoted context omitted.
Interesting concept, but I fail to see how it can model the whole universe. Describing it, maybe, but the universe being a graph, well for a start, what is the graph made of? Is it "material" is it "information"?
Any fundamental theory of the universe will have to posit a bottom, base structure that everything else is "made" out of... ...but therefore that base isn't ever going to be made of anything itself, by definition. It just is . It is what it's described as -- no more, no less. It's not going to be material or energy. I suppose "information" is probably as good a word as any if you want to think of it that way.
I think that's being too closed minded about what a fundamental theory of the universe will look like. The only way it could be like that is if that fundamental structure is the only fully general option available.
Re: The Wolfram Physics Project
#295K.H. Knuth, a professor at Albany, has been working on this for some time. He also has some results about QM.
A free version of his paper "A Potential Foundation for Emergent Space-Time" (2014). What Wolfram is talking about seems to me a consequence of the principles K.H. Knuth has been investigating since at least 2011.
Re: The Wolfram Physics Project
#296https://en.wikipedia.org/wiki/Arthur_Eddington#Fundamental_t...
"Eddington believed he had identified an algebraic basis for fundamental physics, which he termed 'E-numbers' .... These in effect incorporated spacetime into a higher-dimensional structure. While his theory has long been neglected by the general physics community...."
Re: The Wolfram Physics Project
#297Earlier quoted context omitted.
There's a pernicious effect going on, though. You can see on the Twitter threads about this that people are asking physics professors what they think -- and they're all weaselling out, saying stuff like "No comment." Why? Because from decades of experience they know that nothing is going to stop the hype train: at best they'll be ignored and at worst they'll be tarred in some articles as hidebound reactionaries. But…
You're welcome to criticize substantively. I took a quick look at your comments and didn't see any WDS. Maybe just a little.
Re: The Wolfram Physics Project
#298I don't see anything of substance here, besides a lot of pretty graphs. Just like Wolfram's "A New Kind of Science", we have the problem that there is a vast gulf between what you need to make flashy popsci and what you need to make a real physical theory. In increasing order of difficulty, you need to: 1. make a set of dynamical rules that matches general relativity in the low energy limit, such as recovering Lorent…
This reminds me what Feynman talk to us: https://www.youtube.com/watch?v=NM-zWTU7X-k > If you can find any other view of the world which agrees over the entire range where things have already been observed, but disagrees somewhere else, you have made a great discovery. It is very nearly impossible, but not quite, to find any theory which agrees with experiments over the entire range in which all theories have been ch…
Right now I'm toying around with a particularly mathematically elegant model with (IMHO) incredibly beautiful "symmetry" in the sense that the equations are both trivially simple yet capable of producing a rich particle zoo, but still limited to a small finite set. My problem is that I'd need a few petabytes of memory to play around with it sufficiently to see if it passes the basic tests.
I'm hoping Moore's law will allow me to run some simulations before I die of old age...
Re: The Wolfram Physics Project
#299After a few iterations, I think I understand the point of this piece. It was a bit difficult to hone in on, though. The article suggests that working out the theory of something like rule production systems, and then figuring out how that theory relates to existing insights from physics, is the best path toward a Fundamental Theory of Physics. My primary source of skepticism stems from the fact that the theory of rul…
"However, were the book more cautious in its claims and more willing to acknowledge previous work, it would likely be easier for readers to assess what it does offer: a cellular-automaton-based perspective on existing ideas in science"
Re: The Wolfram Physics Project
#300I don't see anything of substance here, besides a lot of pretty graphs. Just like Wolfram's "A New Kind of Science", we have the problem that there is a vast gulf between what you need to make flashy popsci and what you need to make a real physical theory. In increasing order of difficulty, you need to: 1. make a set of dynamical rules that matches general relativity in the low energy limit, such as recovering Lorent…
I have an unfounded suspicion that there exists a simple algebra akin to a continuous geometric algebra that allows all of physics and only physics.
Something that's bothered me for years about contemporary physics is the use of constraints "on top of" a general purpose algebra over the infinite precision real or complex numbers.
Mathematicians would argue that it's all "equivalent", but to me it feels arbitrary and in a sense missing the point. The final theory whatever it is, shouldn't sound like "everything except almost everything leaving one thing". It should sound like "this one thing only, that can be no other thing".
A friend of mine once put it this way: Ask a mathematician to describe a Rubik's Cube and he'll start with the space of all possible transformations, whittle it down to some space of discrete modular transformations by throwing out all other continuous and infinite transformations, then by throwing out even more transformations eventually wind up with a set of rules that matches a Rubik's Cube. If you ask him to draw what it looks like he'll start spouting about how that's impossible and you just need to "learn the maths", pointing at a stack of textbooks.
Modern theoretical physics has the same problem.