Reversible computing seems like a fascinating possibility, but it is pretty
far off. even if economically feasible and mass producible reversible
physical logic gates and chip architectures were to be discovered today, the
inertia of the existing code base would take many decades to work its way
through the life cycle. Attempts to promote the parallelization of
algorithms also face this legacy problem as well.

But by the time (if ever) a reversible set of the basic logic gates AND,
NAND, OR, XOR are discovered - perhaps algorithms will have become so
sophisticated that an existing legacy code base could be run through the
various analyzers etc. and the "intent" of the code could be discovered by
an automatic self-tending process that could then use this map as a template
in order to perform code generation of equivalent user facing functionality
- and so is an essentially seamless experience for the user - but that has
been radically re-architected, re-factored & recompiled into code that works
with a reversible architecture.

A similar strategy could be used for achieving the maximum feasible
parallelization of algorithms/code - by automatically re-writing the code
base.. For quantum computing algorithms (i.e. code) as well. 

All still some ways off into the future though. just somewhat pie in the sky
musings.

 

 

 

From: everything-list@googlegroups.com
[mailto:everything-list@googlegroups.com] On Behalf Of John Clark
Sent: Friday, September 20, 2013 8:50 PM
To: everything-list@googlegroups.com
Subject: Re: What gives philosophers a bad name?

 

 

 

On Fri, Sep 20, 2013 at 4:22 PM, Chris de Morsella <cdemorse...@yahoo.com>
wrote:

>> A computation always takes a nonzero amount of energy to perform,
theoretically you can make the energy used be as close to zero as you like,
but the less energy you use the slower the calculation.

 

> How does that square with the increased (well measured) energy efficiency
per fundamental unit of logic (single machine operation) -- it takes far
less energy to perform an elementary logic operation on a modern CPU than it
did on say a CPU from ten years ago 

 

I'm talking about the theoretical limit dictated by the laws of physics,
right now we are nowhere near that and technological factors are
astronomically more important. According to Landauer's principle the minimum
energy to change one bit of information is, in joules, kT*ln2 where k is
Boltzmann's constant and T is the temperature in degrees kelvin of the
object doing the computation. A joule is a very small amount of energy, one
watt hour is equal to 3600 joules, and Boltzmann's constant is a very very
small number, about 10^-23, so it will be some time before we have to start
thinking seriously about ways to overcome this theoretical limit with
something like reversible computing. 

   John K Clark


 


 


 

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