[HN Gopher] A New Map of All the Particles and Forces (2020)
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       A New Map of All the Particles and Forces (2020)
        
       Author : frutiger
       Score  : 31 points
       Date   : 2022-04-16 20:26 UTC (2 hours ago)
        
 (HTM) web link (www.quantamagazine.org)
 (TXT) w3m dump (www.quantamagazine.org)
        
       | PaulHoule wrote:
       | What I like of the right-hand, left-hand split is that it
       | emphasizes the mystery of neutrinos.
       | 
       | We know neutrinos have a mass, we don't know how much. We don't
       | know how to incorporate the neutrino mass into standard model.
       | Other fermions come in left-handed and right-handed forms but we
       | only see left-handed neutrinos.
       | 
       | One idea is that right-handed neutrinos do exist but are highly
       | elusive. In fact they are a good answer to the dark matter and
       | other physics mysteries
       | 
       | https://arxiv.org/abs/1303.6912v3
        
         | ncmncm wrote:
         | That the total mass of neutrinos is commensurate with / exceeds
         | all the hadronic mass is rarely mentioned. With so many
         | interactions emitting neutrinos, does everything end up as
         | neutrinos, finally (neglecting expansion)? Or does something
         | consume neutrinos and yield net hadronic stuff?
        
           | PaulHoule wrote:
           | Particles like protons and electrons can never turn entirely
           | to neutrinos because electric charge is conserved. Protons
           | and bound neutrons seem to be the only stable configuration
           | of quarks & gluons, ultimately there is quark charge that is
           | conserved that prevents quarks from going away unless protons
           | really do decay... which would have to happen at a very low
           | rate if it does.
        
       | est31 wrote:
       | The article is two years old, and one of the links, the one
       | pointing to https://www.cpepweb.org/cpep_sm_large.html is already
       | dead.
       | 
       | Thankfully the internet archive has a backup:
       | http://web.archive.org/web/20200521151158/https://www.cpepwe...
        
       | tejohnso wrote:
       | Is this model actually taught in high schools at this point?
       | 
       | I remember being taught about electrons with their valence
       | shells, protons, and neutrons. That's it. I didn't hear about a
       | boson or a neutrino until well into adulthood.
        
       | bsedlm wrote:
       | why is the absolute overwhelming majority of stuff in the
       | universe (and 100% of things outside of special lab settings)
       | made up from 1st generation matter?
       | 
       | why is it that all stuff made from charm, strange, top, and
       | bottom, quarks decays right away?
        
         | green_on_black wrote:
         | why are there generations at all? why 3?
        
           | ncmncm wrote:
           | Might we just not wield enough energy to evoke a 4th
           | generation?
        
             | PaulHoule wrote:
             | https://en.wikipedia.org/wiki/Generation_(particle_physics)
             | #...
        
         | frutiger wrote:
         | > why is the absolute overwhelming majority of stuff in the
         | universe (and 100% of things outside of special lab settings)
         | made up from 1st generation matter?
         | 
         | The first generation have the lowest mass, and there are
         | interactions between generations. Since physical systems like
         | to explore the local energy space and find the lowest one, it
         | follows that more energetic systems will quickly stabilize to
         | lower energy configurations.
         | 
         | You might rightfully have two follow up questions at this
         | point:
         | 
         | 1. Why do the first generation fermions have the lowest mass?
         | 
         | 2. Why do physical systems like to find the lowest energy
         | configuration?
         | 
         | I don't believe anyone has the answers to those - so far as we
         | can tell this is just the way the universe is. Maybe some day
         | someone will figure out why.
        
           | ncmncm wrote:
           | Does thermodynamics not suffice for (2)? Or does that just
           | restate the question, somehow?
           | 
           | I learned many things about the SM from this presentation I
           | had never before retained.
           | 
           | Wondering now to what degree string theory seems to exactly
           | require all of this, vs. merely be apparently compatible with
           | it, insofar as it can be "solved" at all. Where it is too
           | hard, maybe it is not known whether certain SM features are
           | compatible, and everyone just hopes?
        
             | PaulHoule wrote:
             | By thermodynamics: energy is conserved globally so when a
             | protein molecule relaxes to a minimum energy configuration
             | the energy gets transferred from the protein molecule to
             | its environment. Total energy stays the same but it is more
             | spread out. There are dramatically more possible ways the
             | energy could be spread out than be bunched together: so if
             | it starts out in a bunched out state it will spread out
             | unless there is something, usually a "conserved quantity"
             | or quantum number that makes it impossible for the state to
             | roam randomly across the phase space.
        
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       (page generated 2022-04-16 23:00 UTC)