Owen Maroney
(1970?-)
Owen Maroney wrote his Ph. D. thesis at Birkbeck College London under
B. J. Hiley. Hiley was the chief collaborator of
David Bohm, since Bohm joined the Birkbeck faculty in the early 1950's. In 1993 Bohm and Hiley completed their important book,
The Undivided Universe, just before Bohm's death. It is a major defense of "Bohmian Mechanics," which combines contributions from Bohm,
Louis de Broglie, and
John Bell.
Maroney's thesis was titled "
Information and Entropy in Quantum Theory."
Maroney authored the 2009 Stanford Encyclopedia of Philosophy article "
Information Processing and Thermodynamic Entropy." It includes an excellent review of Maxwell's Demon, as critically examined by
Leo Szilard,
Leon Brillouin, and then by
Rolf Landauer and his younger colleague
Charles Bennett.
Landauer extended the ideas of
John von Neumann and Szilard, who, along with many other physicists (e.g.,
Jerome Rothstein), had connected a
physical measurement with thermodynamical
irreversibility, that is to say a dissipation of available (free) energy and an increase in entropy. To acquire a single bit of information would require at least
kT of available (free ) energy (k of negative entropy), and of course far far more if it is being done on an actual computer.
Landauer had begun research into the idea of "logically reversible" computing with a
1961 article for the IBM Journal.
Maroney points out that reversing a NOT gate is easily logically reversible, because there is a one-to-on relationship between inputs and output. A triple AND gate is not even logically reversible, since multiple possible inputs produce the same output. Unless all those states are saved somewhere, there is no going back.
The desire for logical reversibility is closely related to the idea of
physical reversibility, which in turn is based on the idea that the fundamental equations of physics are time reversible, notably the non-relativistic Schrödinger equation and the unitary transformations of quantum field theory.
Behind this is the
belief in
determinism, an idea that
Ludwig Boltzmann, his colleague
Franz Exner and even the young
Erwin Schrödinger said "goes beyond experience."
Determinism as a
theory can only be established on the basis of
experiments, which are always
statistical. Determinism remains a quasi-religious
belief.
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