X-Message-Number: 8531
From: Andre Robatino <>
Subject: Re: CryoNet #8521 - #8526
Date: Wed, 3 Sep 97 20:13:29 EDT

> Message #8521
> Date: Tue, 2 Sep 1997 09:58:09 -0700 (PDT)
> From: John K Clark <>
> Subject: Analog Computing
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> 
>         >>Me:
>         >>Light moves at 300,000,000 meters a second, signals in the brain
>         >>move at 100, lots of room for improvement.
>            
>         >"John P. Pietrzak" <>
>         >Maybe.  Of course, you're still talking digital signal here. What if
>         >it's an analog computation?  
>            
> 
> Welcome to the exciting world of analog computing. Thanks to the new Heath 
> Kit Home Study Course, you can build your very own analog computer in the  
> privacy of your own home. Make big bucks! Amaze your friends! Be a hit at  
> parties! This is a true analog computer folks, no wimpey pseudo analog stuff 
> here, this baby can handle infinity.
> 
> Before we begin construction there are a few helpful hints I'd like to pass 

> along. Always keep your workplace neat and clean.  Make sure your computer is
> cold, as it will not operate at any finite temperature above absolute zero. 
> Use only analog substances and processes, never use digital things like  
> matter, energy, momentum, spin, or electrical charge when you build your 
> analog computer. 
> 
> Now that we've got those minor points out of the way we can start to build 
> your analog computer. 

  This is ironic - you posted a positive message a few months ago regarding
Seth Lloyd's quantum simulator article in Science.  But these are special-
purpose analog computers for computing the evolution of quantum systems (a
domain for which standard digital computation is out of its league for
anything more than a small number of particles over a short period of time).
Although full-fledged quantum computers would be digital in nature, and would
be able to do anything a quantum simulator would, it's iffy at this point in
time whether practical ones can be built - basic problems still have to be
solved.  Practical quantum simulators, on the other hand, are essentially a
sure thing.

> 
> Step One: Repeal the Heisenberg Uncertainty Principle. 

> Step Two: Use any infinitely accurate measuring stick you have handy and ...
  The problem of finite accuracy of input affects any simulation of a physical
system, regardless of what form of computation is used.  If an analog
computation is done in such a way that the _major_ loss of accuracy is in the
input, then the additional loss of accuracy in the computation is tolerable.
You forgot to mention a bigger problem with analog computation, namely
inflexibility.  But this is solvable.  For an outline of how, see
<http://www.nytimes.com/library/cyber/surf/050797mind.html> and the related
links at the bottom of the page.  This should be possible to implement within
a few years.  Also, greatly improved sensor technology will create more demand
for computers which can interact with physical systems in real time.  Digital
computation will generally be too slow for this, creating a large niche for
analog computation.  Thus a major comeback for analog can be expected within
5-10 years.
  Regarding the original comment, I believe that according to the best
available knowledge, the brain uses some poorly-understood combination of
digital and analog computation.  So it's indeed not obvious what the exact
ratio of computing power is.  It almost certainly does _not_ use any form of
quantum computation, though, which means that it's almost certainly not
necessary to use this to make computers capable of playing Go at an expert
level (to answer someone else's remark from a while back).  Clever programming
and fairly familiar hardware should suffice.

>         .      
>         .
> 
> Step Infinity: ...
>                                                 
>                                              John K Clark     

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=8531