Thursday, October 13, 2005

model building in physics

I've been doing some reading for a history of science class.
There was an interesting article by Steven Weinberg on his views of Kuhn's "Structure.."
There was also in interesting article by Philip Anderson on emergent properties. He says that the reductionist assumption doesn't imply the "constructionist" assumption. As far as construction, he focusses on the issue of symmetry breaking and notes how complexity can approximately break a symmetry or introduce a new one.
I already knew this, but it emphasized two aspects to physics research. One is finding an appropriate model for a situation. The other is grounding that model in lower level laws. The lower level laws may or may not be the original inspiration for the model.

I went to an ice cream party at slac yesterday celebrating the achievement of 10^34 1/cm/s luminosity in PEP-II. I was talking to some particle physicists and one of them made the usual comment that accelerator physics "is just applied electromagnetism". I agree with this statement except for the implications of the word "just". As one moves up the reduction/construction ladder, one adds new elements, boundary conditions is perhaps a technical way of saying it that are really just approximate in the underlying theory. But why am I doing degenerate perturbation theory on symplectic matrices and working with stochastic differential equations? Am I really "just" applying Maxwell's equations?

I like this topic and I'd like to discuss it in a way that goes beyond sour grapes at not getting my fair share of respect. The article by Anderson closes by saying something like that perhaps we've gone beyond the arrogance of particle physicists thinking that all science is applied quantum field theory. But that we have a long way to go to get beyond the biologists thinking that all psychology and genetics is "just" applied biology. He suggests that there are probably many more hierarchicaly significant levels between human behavior and biology than between say chemistry and quantum field theory.
Why is it that supposedly "smart" people (like myself) need to constantly be reminded of such obvious things. I think it has to do with what I wrote awhile ago about the problems of focussing too much on one particular area and the (necessary?) lack of perspective that can result.

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