Physics and Economics

[Herbert Gintis <gintis@xxxxxxxxxxxxxxx>]

Johan Hauknes writes: (BTW, could you use shorter lines--I had to
reformat this before replying to it. Thanks!)

Herb Gintis wrote

   .....only in classical physics BTW  .....

On the contrary, the field where this is most extensively used is in
qunatum field theory, most systematically in terms of local gauge
symmetry. Well known examples are are quantum electrodynamics (the
quantized form of electromagnetism) in quantum chromodynamics and
electroweak interaction (the Weinberg-Salaam model, the unification of
QED and the so called weak interaction betweens elementary particles ).

	Yes, but the uncertainty principle implies that energy is not
locally conserved.


The symmetry corresponds to charge conservation as in QED. But in
addition there's a fact that the actual world does not conserve all
the electroweak charges. The interpretation is that the symmetry is
dynamically broken, i.e. through the dynamics of the theory there
arises (energydependent) interactions which below a certain energy
breaks the symmetry.

	This is what I meant. BTW, if I had to say what is really
presupposed by most modern physics is the notion of symmetry, or more
generally, that the properties of particles are determined by the
group of transformations under which their properties are conserved.
Is this supposed to underly economics? Perhaps. We lump things
together (factors, consumer goods,...) according to their having
common properties. But this also seems far fetched.

I liked Mirowskis book, but I think that the parallell between the two
fields has more of historical than real interest.

	I would not say that 'historical' can be opposed to 'real',
but I'm pleased that someone trained in physics and economics agrees
that the issue is not of of relevance to current research.

Economics is not social physics in any interpreation of the term. But
htat does not exclude the possibility that something can be learned
both ways. (Is it something I hate, then that is disciplinary
arrogance, both from physicists, economists.....  and other.)

	Both physics and economic are difficult to learn, and few are
competent in both. This is not necessarily arrogance (although it
surely exists).

	Thanks for the 'expert' opinion.

Herb gintis@xxxxxxxxxxxxxxx