Russ, I think Bruce was using the traditional photon explanation (particles, or particle/waves as primitives) as a setup to introduce the more novel approach of treating fields as primitives.
This is more appealing to me and tends to be how we write agent-based models that scale. In fact, one of my rants is that ABM might be better named interaction-based modeling as the models tend to focus on the interactions and not the properties of agents (particles). As one scales up the populations and interactive forces, we tend to convert the interactions to local moving fields (eg pheromone fields around ants, quadtrees in flocking to reduce n^2 interactions to NLogN, etc). On Fri, Apr 19, 2013 at 9:08 PM, Russ Abbott <russ.abb...@gmail.com> wrote: > Thanks for all the answers. To answer John's question first, magnetism > doesn't seem miraculous (it's too familiar), but I can't say I understand > how it works. It was just that question about magnetism that Feynman was > asked as the start of the video<http://www.youtube.com/watch?v=wMFPe-DwULM> in > which he danced around the question before saying he couldn't give an > intuitive answer. > > What would a satisfying answer look like? That's a very good question. > Superficially it would be something like a sophisticated version of > billiard balls: when one hits another, energy is transferred. But even that > doesn't work well when looked at carefully. What happens in detail when > one hits another. If the two objects were absolutely solid, how would one > "feel" the impact of the other. Would the transfer simply become a > primitive? If they were somewhat springy, how does that springyness work? > And besides, there must be some surface-like thing that receives the impact > and something more internal that absorbs it. > > Bruce's QM photon explanation is pretty close to what I'm looking for, but > as he notes, it only works for repulsive forces. It also relies on > primitives. In that case the emission and absorption of a photon and the > associated transfer of energy seem to be primitive actions. > > The papers by Hobson look very interesting. They even look like I can read > them. I haven't done that yet, though. > > As a software person, a good explanation is often something like an API. > How does one object interact with another? We know that objects have > capabilities (specified by their APIs), and that it's possible for one > object to trigger the performance of a capability in another object. We > don't ask how the triggering event gets from one to the other. That's magic > at a lower level. We just assume that it can happen and that there isn't > anything more to say about it at the object level of abstraction. > > So I would be (somewhat) happy with an answer that said (a) what the > capabilities are (something like a API for elementary particles/fields) > and (b) what the non-decomposable primitive actions are, e.g., like emit > and absorb. > > > > > *-- Russ Abbott* > *_____________________________________________* > *** Professor, Computer Science* > * California State University, Los Angeles* > > * My paper on how the Fed can fix the economy: ssrn.com/abstract=1977688* > * Google voice: 747-*999-5105 > Google+: plus.google.com/114865618166480775623/ > * vita: *sites.google.com/site/russabbott/ > CS Wiki <http://cs.calstatela.edu/wiki/> and the courses I teach > *_____________________________________________* > > > On Fri, Apr 19, 2013 at 7:06 PM, John Kennison <jkenni...@clarku.edu>wrote: > >> Russ, >> >> Before people knew about magnetism, it must have seemed miraculous that >> two stones would spontaneously start to move toward (or away from) each >> other. Now we can say, "Oh, it's just magnetism". But if we think about >> long enough, we may still wonder how two objects can move toward or away >> from each other. My question would be, "Does magnetism still seem a bit >> miraculous, or do you feel your question is answered, at least for >> magnetism? In either case, what would a satisfying answer look like?" >> >> John >> >> ________________________________________ >> From: Friam [friam-boun...@redfish.com] on behalf of Russ Abbott [ >> russ.abb...@gmail.com] >> Sent: Friday, April 19, 2013 1:50 PM >> To: FRIAM >> Subject: [FRIAM] How do forces work? >> >> Yesterday I asked this question< >> http://physics.stackexchange.com/questions/61542/how-do-forces-work?noredirect=1#comment123788_61542> >> on StackExchange: physics. >> >> Is there a mechanistic-type explanation for how forces work? For example, >> two electrons repel each other. How does that happen? Other than saying >> that there are force fields that exert forces, how does the electromagnetic >> force accomplish its effects. What is the interface/link/connection between >> the force (field) and the objects on which it acts. Or is all we can say is >> that it just happens: it's a physics primitive? >> >> So far, there haven't been any answers that feel satisfying--although, >> please look at them yourselves. One of the comments pointed to a 7 1/2 >> minute video by Feynman, in which he talks around the problem before >> finally saying he can't provide an intuitive explanation. I don't think it >> was one of his better efforts. Does anyone on this list have an answer? >> >> -- Russ Abbott >> _____________________________________________ >> Professor, Computer Science >> California State University, Los Angeles >> >> My paper on how the Fed can fix the economy: ssrn.com/abstract=1977688< >> http://ssrn.com/abstract=1977688> >> Google voice: 747-999-5105 >> Google+: plus.google.com/114865618166480775623/< >> https://plus.google.com/114865618166480775623/> >> vita: sites.google.com/site/russabbott/< >> http://sites.google.com/site/russabbott/> >> CS Wiki<http://cs.calstatela.edu/wiki/> and the courses I teach >> _____________________________________________ >> > > > ============================================================ > FRIAM Applied Complexity Group listserv > Meets Fridays 9a-11:30 at cafe at St. John's College > to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com >
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