4 ms·
Which are the two things that combine to nothing?
by DrDeWitt 3y ago
Which are the two things that combine to nothing?
- GolDDranks 3y agoParticles and antiparticles. But I think he's trying to make a slightly more general point: why are "parities" (2-fold symmetries) so common in nature and mathematics? Why not more 3-fold symmetries?
- DrDeWitt 3y agoAs the other reply said, in QCD you have "3 things that combine to nothing." If I had to guess why they are not so common I would say that the more variables you add in a theory the more complicated you make it. So by Occam's razor we try to go for the simpler models/structures.
- andyferris 3y agoOne line of thought here is that maybe there do exist larger, more complex symmetry groups that can broken to create more complex "charge" particles (e.g. electric charge < color < something else < ...), but that the masses of particles involved are so large, their lifetimes so short, etc, such that we'd never actually observe them (or at least, we can't yet observe them) and that the more complex the group, the less relevant the physics actually becomes. (Obviously I can't say whether that is true or not, but it might be a possible explanation of current observations).
- truckerbill 3y agoOccam's razor is a heuristic not a law so this isn't really a satisfactory explanation
- im3w1l 3y agoMaybe sound is an illustrative example. The air pressure is a positive scalar quantity. We are interested in the deviations from the mean. Deviations can be both positive and negative. A positive and a negative deviation cancel (in absolute terms: a larger than normal pressure and lesser than normal pressure will average to something more typical)
- andyferris 3y agoThis is a good explanation for e.g. electric charge (which is scalar, just like presure), but color in QCD really is a bit more multidimensional in behavior where you can get things like red + green = -blue and so-on.