From: Robert Harley
Subject: Re: Switching (was: Will Java VM kill Lisp? How to fight it.)
Date:
Message-ID: <5ij1hn$k1v@news-rocq.inria.fr>
······@netcom.com (Henry Baker) writes:
>Jan Vorbrueggen <···@mailhost.neuroinformatik.ruhr-uni-bochum.de> wrote:
>>Have you ever read Dennis Gabor's 1949 paper in the IEE proceedings?
>Yes. It's a good start, but not much has been done in the mean time
>to build on it.
Ahem, except by von Neumann (1966), Bennett (1973, 1982), Fredkin and
Toffoli (1982), Feynman (1984), Bennett and Landauer (1985) etc.
>As readers of PhysComp Proceedings, etc., already know, even close
>approximations to reversible computations help _a lot_. [...]
>it sure beats the heck out of boolean and/or logic.
There's always hot-clocking.
-- Rob.
From: Henry Baker
Subject: Re: Switching (was: Will Java VM kill Lisp? How to fight it.)
Date:
Message-ID: <hbaker-1004971328420001@10.0.2.1>
In article <··········@news-rocq.inria.fr>, ······@pauillac.inria.fr
(Robert Harley) wrote:
> ······@netcom.com (Henry Baker) writes:
> >Jan Vorbrueggen <···@mailhost.neuroinformatik.ruhr-uni-bochum.de> wrote:
> >>Have you ever read Dennis Gabor's 1949 paper in the IEE proceedings?
> >Yes. It's a good start, but not much has been done in the mean time
> >to build on it.
>
> Ahem, except by von Neumann (1966), Bennett (1973, 1982), Fredkin and
> Toffoli (1982), Feynman (1984), Bennett and Landauer (1985) etc.
Perhaps I should have been more explicit. The later people you reference
have done a lot, but I wouldn't classify the later work as 'based on'
Gabor's work. They were all trying to get at some of the same issues, but
I've seen very little that followed up specifically on Gabor's ideas.
Gabor's stuff should have found a home in electrical engineering -- particularly
in communications theory -- but I've never seen much in that direction.
The Gabor paper I have in my files is
Gabor, D. "Communication Theory and Physics". Proc. Symp. on Info. Theory,
Ministry of Supply, London, 1950.
Here is the abstract:
"The electromagnetic signals used in communication are subject to the
general laws of radiation. One obtains a complete representation of a
signal by dividing the time-frequency plane into cells of unit area and
associating with every cell a "ladder" of distinguishable steps in
signal intensity. The steps are determined by Einstein's law of energy
fluctuation, involving both waves and photons.
"This representation, however, gives only one datum per cell, viz.
the energy, while in the classical description one has two data; an
amplitude and a phase. It is shown in the second part of the paper that
both descriptions are practically equivalent in the long-wave region,
or for strong signals, as they contain approximately the same number of
independent, distinguishable data, but the classical description is always
a little less complete than the quantum description. In the best possible
experimental analysis the number of distinguishable steps is the measurement
of amplitude and phase is only the fourth root of the number of photons.
Thus it takes a hundred million photons per cell in order to define
amplitude and phase to one percent each."
See also
Gabor, D. "A Further Paradox: `A Perpetuum Mobile of the Second Kind'".
In Leff, H.S., and Rex, A.F. (eds.) Maxwell's Demon: Entropy, Information,
Computing. Princeton University Press, 1990. ISBN 0-691-08727-X.