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From: cipher@mmm.UUCP (Andre Guirard)
Newsgroups: sci.physics
Subject: Re: Minor nit on psi experiment
Message-ID: <1090@mmm.UUCP>
Date: Mon, 10-Nov-86 18:07:35 EST
Article-I.D.: mmm.1090
Posted: Mon Nov 10 18:07:35 1986
Date-Received: Thu, 13-Nov-86 22:05:49 EST
References: <236@sri-arpa.ARPA> <3782@columbia.UUCP>
Reply-To: cipher@mmm.UUCP (Andre Guirard)
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Organization: Software & Electronics Resource Center/3M
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In article <3782@columbia.UUCP> zdenek@heathcliff.columbia.edu.UUCP (Zdenek Radouch) writes:
>>From:  "Keith F. Lynch" <KFL%MX.LCS.MIT.EDU@MC.LCS.MIT.EDU>
>>
>>  A true random number generator might be a speck of radium with a
>>Geiger counter next to it.  A silicon device, i.e. computer, can only
>>be a pseudo-random number generator.  The numbers that are produced by
>>it may be well distributed, but they only APPEAR random - because of
>>our lack of knowledge of the algorithm....
>
>Sorry, the life isn't that simple. Let's not argue about true or pseudo
>random numbers, philosophers will do it for us.

No, let's argue about true and pseudo random numbers.  The distinction
really is simpler than you apparently think.  If your RNG is
deterministic, i.e. if by knowing its current state you can deduce its
future state, then it's a pseudo-RNG.  A digital computer running a
random number program, assuming the hardware is working correctly,
falls into this category.  A true RNG is by definition unpredictable.
An RNG based on phenomena such as atomic decay, which most physicists
_believe_ to be non-deterministic, falls into this category.

The important distinction for a PSI experiment is that if you use a
pseudo-RNG, you can't absolutely rule out the possibility that the
subject knows or has (perhaps subconsciously) deduced the algorithm
which generates the numbers.

And the other important point, which you cut out of your quoting from
the other article, is that if a subject can influence the outcome of a
_deterministic_ process then there's some funny business going on.  A
person who can do this should also be able to get the following program:

	do forever {
	    print "1"
	}

to print something other than "1".  Or an easier task, to get a
computer to crash just by concentrating at it.  This is easy to do by
just randomly changing memory locations, after all.

>We use computers because it's easy to get any distribution we want and
>the process is controlled. If you don't understand the mechanism of
>generating the numbers you just get some numbers and you have to analyse
>them.

And this is fine for statistics experiments and simulations.  Not so
good, as I said, for PSI experiments where the true source of the
"randomness" is very important.

> As a result you could say they have such and such distribution, but
>that doesn't imply that the numbers to be generated next will have the
>same property.

But we hope that they will!!!-)

>As far as the examples you used, a Geiger counter counts 0,1,2,3,4,5,6....
>That sequence can hardly be considered to be random. The only way to make
>it what you call "true random number generator" would be to build some
>fairly sophisticated hardware around it.

Dum de dum... It was fairly clear to me that this is what was meant.

> Even then it wouldn't generate
>the numbers with required distribution; it's simply too complicated.

I can think of a fairly easy way to generate numbers with a uniform
distribution this way.  Then you use those as input to an algorithm
(see here's where the computer should come in) that uses them to
generate the distribution you want.

>... A mathematical model is just the easiest and most reliable
>approach.

True.  Unfortunately in PSI experiments there are factors which would
cause us to reject the easiest and most reliable way for something more
theoretically sound.  After all, much PSI research is, in a sense,
research into the nature of probability.  For this we want to use
"real" probability and not a computer simulation.

"Oh come on!  You don't really need a cyclotron for your particle
physics experiments.  You can simulate all that stuff on a computer!"

===+===                                         Andre Guirard
 /@ @\                                          ihnp4!mmm!cipher
/_____\
( @ @ )    "Well, yes, I'm opinionated.  But only about
 \ _ /      those subjects where I know I'm right."
  `-'