Excellent series of explanations, Bruce. Do you by chance have a specific
reference to the ten-pin structure and its relation to group theory? Thanks
... Dean Gerber
________________________________
From: Bruce Sherwood <bruce.sherw...@gmail.com>
To: The Friday Morning Applied Complexity Coffee Group <friam@redfish.com>
Sent: Wednesday, July 11, 2012 9:38 AM
Subject: Re: [FRIAM] Celebrating the Higgs - explaning and predicting
Good points, Saul.
If I remember correctly, before the Bohr model, people looking at the
hydrogen emission spectrum had already discovered an empirical formula
for the frequencies of the emission lines:
f = constant*(1/n1^2 - 1/n2^2)
Bohr's model yielded the same formula, with Planck's constant times f
being the energy of an emitted "photon" when the atom's "quantum
number" changed from n2 to n1, and the model also provided an
evaluation of the constant in terms of known quantities such as the
mass of the electron.
I should mention that the ten-pin diagram is a graphical
representation of a particular structure in group theory.
Bruce
On Tue, Jul 10, 2012 at 11:05 PM, Saul Caganoff <scagan...@gmail.com> wrote:
> It seems that many scientific fields go through a phase of observation
> (derisively called "stamp collecting") followed by a phase of
> classification. If you're lucky then patterns can be picked out of the
> classification scheme to "predict" where to look for new entities or new
> interesting phenomena.
>
> The Periodic Table is one of the cited examples. Another example (though
> perhaps not as good) is the Hertzprung-Russell diagram used in astronomy
> where stars are plotted onto a graph with luminosity and colour as the two
> axes. They form a characteristic pattern which had to be explained by any
> theory of stellar evolution.
>
> I also recall many years ago picking up a book on atomic spectra published
> in 1901 - some 12 years before the Bohr theory of the atom - which
> illustrated hundreds of different emission spectra and talked about the
> relationships between spectral line frequencies in terms of waves and
> resonances. It reflected a very interesting point in the science where
> patterns were emerging and calling out for an explanation.
>
> So it seems that a "classification" model can be used to make "predictions"
> - to see if the pattern extends to unobserved areas - and that this can be
> independent of an underlying explanatory theory. I think Gell-Mann's QCD
> models probably fit this idea. The image of the "ten-pin owling skittles"
> pattern and the mystery of what lies at the tip is very evocative.
>
> Regards,
> Saul
>
> On 11 July 2012 06:56, Bruce Sherwood <bruce.sherw...@gmail.com> wrote:
>>
>> "For Engineers perhaps, predictive models are sufficient, they may not
>> be (very?) interested in explaining *why* a particular material has
>> the properties it does, merely *what* those properties are and how
>> reliable the properties might be under a variety of conditions."
>>
>> I don't think this currently true. A big chunk of what used to be
>> labeled "physics" is now in academic engineering departments with the
>> name "material science". This consists of exploiting models that
>> explain observed properties of materials, with the goal of looking for
>> opportunities to change parameters to get improved behavior. In the
>> early 1990s I heard a talk by an engineering professor at the science
>> museum in Toronto, where he explained how such research had led to
>> concrete many times stronger than it had been, and that the iconic
>> tall tower in Toronto could not have been built not many years before
>> it was built, as it relied on much stronger concrete.
>>
>> In some cases someone sees how, starting from fundamental physics
>> principles, one can predict that such and such should happen or be. In
>> other cases an observed phenomenon gets explained in terms of
>> fundamental physics principles (post-diction), which then suggests how
>> changes in the situation might yield an improved behavior. Pre-diction
>> and post-diction both require a deep understanding of how to go from
>> underlying fundamental principles to the behavior, but pre-diction in
>> addition requires the imagination to run the argument forward, not
>> already knowing the answer. That's why I claim that post-diction
>> ("explanation") is more common than pre-diction.
>>
>> There's a fruitful interplay between pre-diction and post-diction. An
>> example I've mentioned some time ago, from our intro physics textbook:
>> When searching for an explanation for spark formation in air (we see
>> the spark and ask how it occurs, which is post-diction or explanation)
>> there are a couple of tentative explanations that one can rule out.
>> Another explanation seems to explain the phenomenon, and the validity
>> of this post-diction is greatly strengthened by noting that it (and
>> not the other explanations) pre-dicts that it takes twice the critical
>> electric field to trigger a spark if the air density is doubled, a
>> pre-diction that is consistent with observations.
>>
>> Bruce
>>
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>
>
>
>
> --
> Saul Caganoff
> Enterprise IT Architect
> Mobile: +61 410 430 809
> LinkedIn: http://www.linkedin.com/in/scaganoff
>
> ============================================================
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> lectures, archives, unsubscribe, maps at http://www.friam.org
============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org============================================================
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Meets Fridays 9a-11:30 at cafe at St. John's College
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