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I 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 gu
by knzhou 7y ago
I 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 Lorentz invariance and the Einstein field equation (this is supposed to be the easiest part -- without at least doing this, a theory of everything is worth less than the graph doodles in my middle school notebooks)
2. demonstrate that you can add something that looks like matter
3. reproduce effects that we know have to appear in quantum gravity in the semiclassical limit, such as Hawking radiation and black hole entropy
4. demonstrate that you can add matter that behaves like the Standard Model
5. make specific predictions that we didn't already know from purely semiclassical considerations
6. find a way to verify those predictions
7. have the predictions actually be correct upon verification
These 7 steps are hard, which is why nobody has managed to do them. But it looks like Wolfram hasn't even bothered to start on step 1. His new book is just hundreds and hundreds of pages of pretty graphs and big words. It's more akin to a reformulation of the foundations of mathematics than a theory of physics -- and it's not a particularly good one, at that.
It's the same complaint I have about category theorists trying to do applied physics. (And category theory is a much more powerful language than Wolfram's!) Yes, you might have an incredibly general language, with which you can talk about vast swaths of possible physical theories. But we already had way too many possibilities using ordinary mathematics! We need to narrow down on specifics, not muddy the waters by making things even more general. I mean, it's like trying to rescue a startup by translating the documentation into Esperanto.
- mjburgess 7y agoIs the following section a beginning of an attempt at that? https://www.wolframphysics.org/technical-introduction/potential-relation-to-physics/ https://www.wolframphysics.org/technical-introduction/potent...
- knzhou 7y agoNot really. It's very vague -- he is just repeatedly saying "well, you could write down X in terms of graphs in this way." But you can write down anything in terms of anything. You can write a compiler in PowerPoint because it's Turing complete. You can write the Bible in Klingon. You can write about making a burrito in category theory. Languages are just packaging. In order to have content, you have to nail down specifics, and here the choice of language can be useful because the specifics might be more naturally expressed in some languages than others. But Wolfram hasn't begun this journey.
- mjburgess 7y agoSure, I agree. However there is value in a phrasing, eg., phrasing classical mechanics in Hamiltonian terms permitted unification with QM, and understanding of non/classical limits. ... also, > In our previous paper[1], we formally introduced the Wolfram Model[2] - a new discrete spacetime formalism in which space is represented by a hypergraph, and in which laws of physics are modeled by transformation rules on set systems - and investigated its various relativistic and gravitational properties in the continuum limit, as first discussed in Stephen Wolfram’s A New Kind of Science (NKS)[3]. Our central result was the proof that large classes of such models, with transformation rules obeying particular constraints, were mathematically consistent with discrete forms of both special and general relativity https://www.wolframcloud.com/obj/wolframphysics/Documents/some-quantum-mechanical-properties-of-the-wolfram-model.pdf https://www.wolframcloud.com/obj/wolframphysics/Documents/so...
- covidacct 7y agoThe substance a good dsl for implementing rewrite/string substitution systems, as well as (likely high-quality) implementations of algorithms causal invariants, knuth-bendix completion, graph isomorphism, etc. [1]. A lot of that pre-existed the Wolfram Physics Project. The new thing appears to be: 1. a rebranding with improved documentation / learning resources for using those features (hey, documentation is hard! discoverability matters!), and 2. a set of really impressive rendering algorithms for visualizing these sorts of systems. (hey, visualizing mathematical objects is quite substantive! I'll happily pay good money for "low-effort pretty charts"!) I addressed in the companion thread why I don't think this is particularly likely to result in "a new type of physics": https://news.ycombinator.com/item?id=22866284 https://news.ycombinator.com/item?id=22866284 Mathematica is good software. Pre-wolframengine I did shell out the $2K for Mathematica because it contains best-in-class implementations of some important algorithms. A high-quality reimplementation that matches Mathematica's performance would take me several years (in an area where I have a phd). Wolfram Research employs smart folks and lets them spend their time writing really high quality code, and the only way to access that code is by calling Mathematica's built-in functions. But just because the goal is perhaps a bit grandois and the presentation definitely breathless doesn't mean there's "nothing of substance". [1] https://www.wolframcloud.com/obj/wolframphysics/Tools/guide-page https://www.wolframcloud.com/obj/wolframphysics/Tools/guide-...
- knzhou 7y agoI do agree that Mathematica is great software! Physics would be much poorer without its help.
- jjoonathan 7y agoSeconded! Nothing beats Mathematica at mapping the concepts of mathematics into software. In certain verticals, sure, but overall? Wolfram has been spinning this flywheel for decades, and it shows.
- h91wka 7y agoMaplesoft Maple is more powerful. hides
- stupidcar 7y agoThe book doesn't seem to be out yet? Do you have access to an advance copy?
- knzhou 7y agoI'm following his "technical introduction" here: https://www.wolframphysics.org/technical-introduction/ https://www.wolframphysics.org/technical-introduction/
- diegoperini 7y ago> I mean, it's like trying to rescue a startup by translating the documentation into Esperanto. I will quote you with this amazing analogy. Thank you!
- jonathan_gorard 7y ago(1) We certainly do have formal derivations of Lorentz covariance and the Einstein field equations, given in detail here: http://wolframcloud.com/obj/wolframphysics/Documents/some-relativistic-and-gravitational-properties-of-the-wolfram-model.pdf http://wolframcloud.com/obj/wolframphysics/Documents/some-re... (2) The article above already discusses the derivation of the matter contribution to the Lagrangian density, the derivation of energy-momentum tensor, and Lorentz transformations for elementary particles. (3) Both Hawking radiation and black hole entropy, and connections between our formalism and the AdS-CFT correspondence, are detailed here: http://wolframcloud.com/obj/wolframphysics/Documents/some-quantum-mechanical-properties-of-the-wolfram-model.pdf http://wolframcloud.com/obj/wolframphysics/Documents/some-qu... (4) We do not yet know how to do this. (5) The quantum mechanics paper above makes, for instance, quite specific predictions about the location of stretched horizons around non-semiclassical black holes. (6) (7) This we are still working on.
- bhouston 7y agoAre you guys planning on submitting your novel findings to peer reviewed physics journals? Have you done that? How has that gone?
- jonathan_gorard 7y agoOur preprints are currently in peer review (for different journals, I should add). Nothing terrible has happened yet.
- caetris1 7y agoAll your points make sense. Also, Wolfram is trying to create a language and tool for others because he very well realizes that his part in all this won't be solving those 7 things.
- naasking 7y ago> But we already had way too many possibilities using ordinary mathematics! We need to narrow down on specifics, not muddy the waters by making things even more general. Building a more general tool can sometimes solve a specific problem than trying to tackle the specific problem directly. I also think you're missing the forest for the trees here. There are many general relationships in physics that are spontaneously appearing in the structure of Wolfram's hypergraphs. That's interesting enough on its own to be worth further research. In one sense, this shared structure shouldn't be surprising, because it's often harder to not make something Turing complete, so in a way I expect a lot of shared structure between physics and various general computational models. On the other hand, it's getting harder to squeeze more progress out of traditional approaches, so shrinking a computational model to exactly match physics on long timescales is a unique attack vector worth exploring.
- comment_ran 7y agoThis reminds me what Feynman talk to us: https://www.youtube.com/watch?v=NM-zWTU7X-k 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 checked, and yet gives different consequences in some other range, even a theory whose different consequences do not turn out to agree with nature. A new idea is extremely difficult to think of. It takes a fantastic imagination.
- jiggawatts 7y agoThis sums up the last decade of my life. In my spare time I stare out the window trying to dream up a "rule system" that coughs up both relativity and quantum mechanics. It's very hard to even reproduce the basics, let alone the more irritating things like the three generations of particles. That in particular is a good "acid test", and it isn't even mentioned by 90% of the conceptual papers I've been skimming. Quantum gravity, loop this, string that... show me three generations and how those particles conspire to make gravity waves, and then I'll be interested. 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...
- miscPerson 7y agoI was curious, so I did the math: It’s $5M/mo to rent 1 PB of RAM on EC2 and $21,000/mo per PB in S3. Conceivably, your dreams will be possible in a decade — they are feasible, but likely too costly now.
- jiggawatts 7y agoThat, or I get way better at mathematics. At this rate, I think Moore's law will win. Apparently TSMC is mass-producing 5nm chips and they're building their 3nm fab...
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- jiggawatts 7y ago> We need to narrow down on specifics 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.