Comment by ralferoo | Hacker News Reader

Comment by ralferoo | Hacker News Reader

I'm not a physicist, so I'm not really qualified to comment on whether a "real physicist" would say the fundamental assertion is true or not, but from a simple linguistics point of view, this article is pure click bait.

At school, I studied physics for 7 years. Nothing I was taught is hinted at by any of these 9 points, or at least in any way I'm able to recognise after receiving all that teaching, except perhaps some of the constants (they're not listed, but I assume there will be an overlap). Did I, in fact, learn absolutely nothing about physics in all those 7 years? It's much more likely to be the case that from a simple linguistics point of view, these 9 lines do not contain "all of physics", but rather than just the parts of physics that the author considers to be the most fundamental. Maybe if you have decades of highly specialised study you have a chance of remembering most of the rest of what's needed to fill in all the (known) gaps and assumptions those 9 lines are based on and hint at. And the fact that each "line" links to an entire volume that tries to fill in those gaps (I have no idea if they succeed in doing that or not), shows that this isn't anywhere close to what it claims to be.

It's about as vacuous a statement as trying to summarise all of maths as "the set of all possible sets" or all of philosophy as "cogito ergo sum".

>but rather than just the parts of physics that the author considers to be the most fundamental.

Fundamental is what "contains all of physics" means in this context (key word: contains). The rest would be emergent properties.

Can the emergent properties be derived from just the nine lines?

I'd say that if a capable scientist like Einstein was given them (assuming they didn't know the rest of the theories), they could build upon them to derive or get to close guesses of large parts of physics. The lines are quite loaded with broad equations that covers very fundamental stuff - including constants and elementary particles.

A few equations being fundamental for big theories built upon them wouldn't be unheard of. Maxwell's equations for example cover several important fields of Physics. Newton's 3 laws cover classical mechanics.

Except the article has a categorical statement: "The 9 lines contain all present knowledge about nature, including all textbook physics and all observations ever made."

Take something simple like "F=ma" which is in lots of textbooks. Nothing in those 9 lines seem to suggest anything that could be used to derive that.

I'm sure a domain expert, who already knows all this stuff, I'm sure they'd be useful as a memory aid to help them trot this stuff out, but do they "contain all present knowledge about nature, ..."? Not so much, if you need a ton of other knowledge to make use of them.

No. Some of them are simply wrong. For instance:

- action is extremized or at a saddle point, not necessarily minimized

- Action is not quantized in QM (and quantum-mechanical action is not quite the same as classical action). There's another very indirectly related notion of "action" which shows up in historical semiclassical approximations and which is quantized. The author has likely confused the two.

- SU(2) is not the gauge group of the weak interaction, because there is no such thing. A purely weak gauge theory with no EM is not possible, on account of having massive force carriers. The SU(2) and SU(1) in SU(3) x SU(2) x U(1) corresponds to weak isospin and weak hypercharge respectively, not weak charge and (EM) charge.

But even if all the errors were corrected there's a huge amount of missing context. (For instance, the actual content of the standard model Lagrangian - the fact that there are 19 free parameters is in no way sufficient to determine it) And even if you had all of that, a full reduction of macrophysics to microphysics is likely computationally intractable, even in principle.

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