At 08:24 PM 10/15/99 +0100, Mick wrote:
>This can easily be acheived by amplifying the shot noise across a PN
>junction.  Zener diodes are a particularly good source of noise.  This is
>random to the same degree as the radioactive decay method already suggested,
>but obviously much more practical.
>
>Once recorded, does a random sequence cease to be random as can now be
>repeated at will, and is surely now - by definition - deterministic? Can
>randomness be quantified?  Any mathematicians out there care to enlighten
>me?

There are a number of tests for 'randomness'. One of the key
characteristics for 'randomness' is that there be no time (or serial)
correlation present. Since the autocorrelation function is the Fourier
transform of the power spectrum, this translates into a requirement for a
constant power spectrum of infinite bandwidth.

One of the best and most accepted tests of 'randomness' is to compute a FFT
and examine the degree of non-constancy of the power spectrum.

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Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: ral@lcfltd.com
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