I wonder if Russ's question relates to a point that was raised in another 
thread –one that I tried to follow --unsuccessfully because it was mostly over 
my head. Nick wrote that:

Again, acting in my capacity as the Village Pragmatist, I would assert that 
science is the only procedure capable of producing lasting consensus.  The 
other methods .... various forms of torture, mostly ... do not produce such 
enduring results.       N.

My first thought was that we would first need language –without language it is 
hard to imagine what consensus would look like and hard to imagine science. How 
could we say that an experiment disproved a hypothesis, or even that one 
experiment is a repetition of another? But without consensus, how do we get 
language? Maybe science and language develop in tandem, --assuming we are 
programmed to believe that gestures and vocal sounds mean something --which can 
be determined through experimentation. This would explain why science seems to 
start with unsophisticated statements such as "Objects tend to fall in a 
downward direction." And why it seems necessary, when grappling with new, 
abstract scientific (and mathematical) ideas to reduce them to simpler 
statements involving ideas we are already comfortable with.  And Russ's 
question might be part of what is needed to understand abstract concepts of 
modern Physics. In 1962 I had a grad course in quantum mechanics (given by the 
Math Dept). It started with a discussion of motion in the physical world and a 
look at some of the questions we would ask. But very soon we adopted the axiom 
that the set of all questions was isomorphic to the set of all closed subspaces 
of a Hilbert space. Even the instructor admitted that this was a bit hard to 
swallow, but once we swallowed all would eventually become clear. I learned a 
lot about operators on a Hilbert space and even got an A in the course, but I 
never connected it to any ideas I had about the physical world. 

________________________________________
From: Friam [friam-boun...@redfish.com] on behalf of Nicholas  Thompson 
[nickthomp...@earthlink.net]
Sent: Sunday, April 21, 2013 3:59 PM
To: 'The Friday Morning Applied Complexity Coffee Group'
Subject: Re: [FRIAM] How do forces work?

I know I am not qualified to join this discussion, but may I say just one thing?

As we struggle with our data from our accelerators n’ stuff, we bring to bear 
models from our experience … metaphors.  The language of your discussion is 
full of such metaphors, and full, also, of expressions of pain that these 
metaphors are not only incomplete  -- all metaphors are incomplete – but that 
they are incompletete in ways that are essential to the phenomena you are 
trying to account for.  Now, it seems to me, that this conversation is like the 
conversation that would ensure if we were to see a unicorn drinking out of the 
fountain at St. Johns, but did not have the mythology of unicorns, or even the 
word, unicorn, to bring to bear.  We would instantly start to apply incomplete 
models.  “It’s a whacking great horse!”  One of us would say.  “Yeah, but, it’s 
got a narwhale tooth sticking out of its forehead.”

Nick

From: Friam [mailto:friam-boun...@redfish.com] On Behalf Of Steve Smith
Sent: Sunday, April 21, 2013 1:40 PM
To: stephen.gue...@redfish.com; The Friday Morning Applied Complexity Coffee 
Group
Subject: Re: [FRIAM] How do forces work?

S -

I'd like to think Gil and I could take credit for running Bruce off with our 
Light/Dark Boson/Lepton nonsensery but I think he's hardier than that!

Carry On!
 - S
Aya, it turns out Bruce recently unsubscribed from FRIAM. I hope you guys on 
the list are happy with your signal to noise ratio ;-)    Just kidding...keep 
it up.

Anyway, Bruce, as I had hoped, had a nice response, albeit offlist. If you want 
to respond to this thread, please cc: Bruce. I copy his response below.

//** Bruce Sherwood response offlist
Feynman diagrams give one visualization of "forces". In this picture, consider 
two electrons moving near each other. With a calculable probability, one of the 
electrons may emit a photon, the "carrier" of the electromagnetic interaction, 
and this electron recoils. The other electron absorbs the photon and recoils. 
At least for electric repulsion, this is a nice way to think about the 
interaction, but it has obvious problems for talking about attraction. The 
exchanged photon is a "virtual" photon which unlike unbound photons has mass. 
At the individual "interaction vertices" (emission event and absorption event) 
momentum and energy need not be conserved, but for the two-electron system 
momentum and energy are conserved.

For the strong (nuclear) interaction, the interaction carrier is the gluon. It 
is thought that the gravitational interaction is carried by a "gravitron" but 
we have no direct evidence for this.

The weak interaction is mediated by the W and Z bosons and is so similar to 
electromagnetism that one speaks of the "electroweak interaction". A key 
example is neutron decay, and here is the story:

http://matterandinteractions.wordpress.com/2012/05/25/neutron-decay/

Or, if you have an up-to-date browser and a graphics card with GPUs, here is a 
central animation from that article:

http://www.glowscript.org/#/user/Bruce_Sherwood/folder/Pub/program/NeutronDecay

On the other hand, the March 2013 issue of the American Journal of Physics has 
a very interesting and perhaps important article by Art Hobson on the modern 
(last few decades) perspective on quantum mechanics. Maybe this is familiar to 
you, but it wasn't to me. The basic idea he reviews is that everything is 
fields; there are no particles. Here is what seems to me a key paragraph in the 
conclusion:

Thus Schrodinger's Psi(x,t) is a spatially extended field representing the 
probability amplitude for an electron (i.e., the electron-positron field) to 
interact at x rather than an amplitude for finding, upon measurement, a 
particle. In fact, the field Psi(x,t) is the so-called "particle." Fields are 
all there is.

There is a popular science book by Rodney Brooks on the subject: At 
amazon.com<http://amazon.com> search for "Fields of Color: The theory that 
escaped Einstein". Brooks was a student of Schwinger, a major contributor to 
quantum field theory.

Here are related references, dug out by Stephen:

  http://physics.uark.edu/Hobson/pubs/05.03.AJP.pdf
  http://arxiv.org/pdf/1204.4616
  http://henry.pha.jhu.edu/henry.hobson.pdf

I've finished the Brooks book. It's not very well written and much of it is 
taken up with material that is familiar to physicists (but needs to be there 
for the nonphysicist reader). The main message is however very clear. He feels 
that it is deeply unfortunate that the quantum field theory (QTF) developed 
especially by Schwinger has been way underappreciated by the physics community 
in general, and the Feynman emphasis on particles (and particle exchange) has 
had unfortunate consequences. He makes a convincing case that for several 
decades the big names (Weinberg, Wilczek, etc.) have all worked within the QTF 
framework. He stresses that wave-particle duality is a mistake which 
unnecessarily makes quantum phenomena more paradoxical than they need be.

I checked with a powerful theorist colleague at NCSU who agrees with the basic 
thrust of these arguments, though he's not comfortable with the phrasing, 
"There are no particles." He says that all reputable quantum field theory texts 
spend a lot of careful time defining what is meant by a "particle" in this 
context.

Bruce

P.S. The Kindle version of the Brooks book had badly mangled format, but a few 
days ago Amazon updated my copy so that it now looks good.

**// Bruce Sherwood response offlist

BTW, the book I recommended to Bruce was by Rodney A. Brooks. I was surprised 
he was writing on QFT and was excited as I assumed it would have a lucid 
explanation as he tends to write well. The book actually isn't as great as I 
had hoped. I had assumed it would be the same Rodney Brooks we know from the 
Alife/robotics world from MIT. Turns out there's another Rodney A. Brooks that 
was in Cambridge, MA with Schwinger who had a career at NIH and then retired to 
New Zealand. Oh well.


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On Fri, Apr 19, 2013 at 3:09 PM, Stephen Guerin 
<stephen.gue...@redfish.com<mailto:stephen.gue...@redfish.com>> wrote:
> Along the lines that Lee is mentioning with fields being the first
> class objects, Bruce Sherwood may be able to illuminate some of the
> current thinking in Quantum Field Theory and how interpretations are
> made with respect to forces.
>
> Bruce?
>
> -Stephen
>
> On Fri, Apr 19, 2013 at 1:36 PM,  
> <lrudo...@meganet.net<mailto:lrudo...@meganet.net>> wrote:
>> Russ asks:
>>
>>> 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?
>>
>> I have the impression that the best you can say is that fields act on 
>> fields; fields are (the
>> only) first-class objects, and what you're calling "objects" are at best 
>> second-class--they
>> are epiphenomena of fields (or, of *the* field).
>>
>> There is (or was when I last tried to look into this, about 40 years ago) a 
>> concept of
>> "current" (which I suppose is a generalization of our familiar "electric 
>> current", but if so
>> is such a generalization that I was unable to see the connection at all) 
>> which was in some way
>> involved with interactions of fields.  Maybe a Google search on current and 
>> Jakiw would turn
>> up something useful, but probably not.
>>
>> ============================================================
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>> Meets Fridays 9a-11:30 at cafe at St. John's College
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