| > The behaviour of _bosons_ is emergent from the behaviour of quarks. I think you mean > The behaviour of _hadrons_ is emergent from the behaviour of quarks. -- Anyway, back to your main idea, the problem is that most of the times the new underlaying theory is even worse than the original one > Newtonian mechanics is emergent from Relativity For Newtonian Mechanics you need only basic calculus. For General Relativity you need curvature, tensors, two definitions of derivatives and other nasty stuff. [I never saw the details, but it's in my todo list.] > Maxwells equations are emergent from quantum mechanics Well, electromagnetism is just the local gauge invariance of the U(1) group. The idea is very simple but each word in that sentence needs like one semester to be decoded. [I saw the calculations a long time ago. I don't remember the details, but I remember the general idea. I wrote a comment with a oversimplified version https://news.ycombinator.com/item?id=8189346 ) > there are theoretical reasons to suspect that quarks do not have any decomposition though. My favorite reason is that for a classic small ball, the ratio of the magnetic moment to the inertia moment is 1 (once you fix some nasty details about units), but for an elementary quantum particle it is 2. For composite particles, there is no theoretical value. https://en.wikipedia.org/wiki/G-factor_(physics) The experimental value for protons is 5.5 and for Neutrons is 3.8, that is not surprising because we are sure they are composed particles. For Electrons and Muons it's slightly more than 2, but we understand that difference quite well (but not perfectly, and that is related to the main point of the article here). I don't think it has been measured directly for Quarks, but my guess is that it's used in some parts of the calculation of some Feynman diagrams, and if it were very different from 2 someone would have noticed. |
>most of the times the new underlaying theory is even worse than the original one
Oh quite. Macroscopic emergent behaviour is often apparently simpler than the underlying causes and is in some way a generalisation of them.