Notebooks
http://bactra.org/notebooks
Cosma's NotebooksenWhen Do Physical Systems Compute?
http://bactra.org/notebooks/2022/03/21#computation-by-physical-systems
<P>Yet Another Inadequate Placeholder
<P>My intuition is to throw the term "computation" around very liberally
for physical processes, but that's partly just
<a href="computational-mechanics.html">how I was raised</a>. I do get how it
sounds odd to say that the planets are computing their orbits, or that
<a href="http://arxiv.org/abs/comp-gas/9704001">collisions of molecules in a
gas just so happen to be computing a complicated logical formula</a>, so I'm
interested in principled restrictions on the use of the term.
<P>See also:
<a href="computation.html">Computation, Automata, Languages</a>;
<a href="computational-mechanics.html">Computational Mechanics</a>;
<a href="chaos.html">Dynamics</a>;
<a href="symbolic-dynamics.html">Symbolic Dynamics</a>;
<a href="physics-computation-information.html">Physics of Computation
and Information</a>
<ul>Recommended:
<li>Marco Giunti, <cite>Computation, Dynamics, and Cognition</cite>
[The first two-thirds has a nice treatment of abstract computers as discrete
dynamical systems, including some apparently new results about non-Turing
computation; the stuff about cognition and scientific explanation seems, by
contrast, strained and tacked-on. By Giunti's standards, no analog computation
is "computation"!]
<li>Matthias Scheutz, "Computational versus Causal
Complexity", <cite>Minds and Machines</cite> <strong>11</strong> (2001):
543--566 ["notions of implementation based on an isomorphic correspondence
between physical and computational states are not tenable. Rather,
`implementation' has to be based on the notion of `bisimulation' in order to
... incorporate intuitions from computational practice. A formal definition of
implementation is suggested ... to make the functionalist notion of `physical
realization' precise. The upshot of this new definition ... is that
implementation cannot distinguish isomorphic bisimilar from non-isomporphic
bisimilar systems anymore, thus driving a wedge between the notions of causal
and computational complexity."
<a href="http://www.nd.edu/%7Emscheutz/publications/scheutz01mm.pdf">PDF</a>]
</ul>
<ul>To read:
<li>Stefano Galatolo, Mathieu Hoyrup, Cristóbal Rojas, "Dynamical systems, simulation, abstract computation", <a href="http://arxiv.org/abs/1101.0833">arxiv:1101.0833</a>
<li>Gualtiero Piccinini, <cite><a href="https://doi.org/10.1093/acprof:oso/9780199658855.001.0001">Physical Computation: A Mechanistic Account</a></cite>
<li>Oron Shagrir, <cite<a href="https://doi.org/10.1093/oso/9780197552384.001.0001">The Nature of Physical Computation</a></cite>
</ul>