Re: modern physics

[Judith Rosen <***>]

The area that my father would say "coding" is entailed by Natural Law is in
the realm of "internal predictive models". These are naturally occurring and
therefore not representative of the usual formalization process.

Judith
----- Original Message -----
From: "Howard Pattee" <***>
To: <***>
Sent: Thursday, May 27, 2004 10:32 PM
Subject: Re: [ROSEN] modern physics


> Tim,
> To keep the postings shorter and to the main points, I will not repeat
everything.
>
> I said in effect that measurement is an act of the observer who chooses
what aspect of world he is interested in. That is the basic reason why laws
cannot usefully describe the process of measurement (and why we must make an
epistemic cut). In Rosen's terms, coding (measurement) is unentailed by
either causal natural laws or the inferential models.
>
> Tim replies: First, I would argue, that in Rosen's view, the last sentence
is incorrect.
>
> HP: I would need some evidence of this. Rosen says (LI p. 61): "We can
already see some peculiar epistemological issues inherent in the diagram of
figure 3H.2 that did not arise earlier. Specifically: what is the status of
the encoding and decoding arrows in that diagram? We already saw in the
exactly similar diagram of figure 3F.2 that the encoding and decoding arrows
were themselves unentailed. But at least they could themselves be considered
as formal objects, since at that point we were comparing syntactric
entailments of two formalisms. But now, we are comparing syntactic
entailment in a formalism with causal entailment in a natural system. The
encoding and decoding arrows in this case are still unentailed, but it is no
longer clear how they could be entailed, or from what."
>
> I have stated Rosen's view much more briefly, but I do not see how you can
reasonably call my statement incorrect.
>
> Tim: In the Modeling Relation, encoding and decoding are unentailed
*within the MR itself*. However, they are not therefore unentailed entirely.
Modeling Relations do occur within the world in which we believe physical
laws operate.
>
> HP: This is your statement, not Rosen's. Of course you are correct, but
the physical entailments on the observer's choice of what to measure is very
weak and exceptionally difficult to pin down. Rosen agrees that in practice
the laws we discover are largely the result of what we choose to observe.
One ultimately then has to face the issue of free will in making such a
choice.
>
> Tim: It is therefore incumbent upon physics to determine the laws
appropriate to describe that physical situation and those entailments, not
to except them from such laws.
>
> HP: Measurement processes are certainly not exempt from laws. In
principle, there is a lawful description (model) of any measurement. What
von Neumann and others have shown is that such a description of a
[system-plus-its-measurement-device] would require additional measurements
leading to a vacuous regress. This can be explained in many ways.
Measurement is inherently a complex process by Rosen's definition because it
has a function (creating a record) that cannot be described by
state-determined dynamics. A complex system, again by Rosen's definition,
requires more than one inequivalent models. Inequivalent here means that
neither model is reducible to, or derivable from, the other. In physics
jargon this is what complementarity means. Consequently, laws and
measurement require complemtary models.
>
> I agree with everything Rosen says about the necessity of relational
models. These are timeless, or synchronic models like symmetry. We also need
dynamical diachronic models. These are complementary models. You cannot
reduce one to the other or derive one from the other. Diachronic models
bifurcate into time-symmetric (reversible microscopic laws) and the
complementary time-antisymmetric models (irreversible thermodynamics). And
so on. There are many cases.
>
> What Rosen says about the limits of state-determined dynamics is certainly
true. My only disagreement with Rosen is his view that physics limits itself
to state-determined dynamics. That is just not the case.
>
> Howard
>