[sdiy] VERY cool/bizarre: Buchla noise

[Grant Richter]

> OK philosphy students... this is a good one frankly. Whenever I try to
> explain PRBS stuff to people (usually customers, usually in regards to
> internet traffic data patterns or framesize distributions) I end up using
> phrases like "it's not really random but it's pretty darn close" and
> "subjectively random" and "it might as well be truly random" and "but it
> will repeat after a while" and "it's generated by a digital machine so it's
> not truly random" etc. etc. Looks like the definition of "random" is what's
> in question here.

Encryption is the process of increasing the entropy level of a signal to the
maximal level. This is equivalent to "noise" as the term is used in
information theory (equal probability of any symbol occurring next).

For a maximally encrypted signal (one that contains information, but seems
like noise) the period of observation becomes a factor. It is not possible
to prove whether a signal is noise, or a maximally encrypted signal unless
the period of observation approaches infinity. At some point, the encrypted
signal will not have a perfectly even probability distribution, while noise
always will.

In other words, from an information theory standpoint, it is all just
probability distributions. A perfectly even symbol probability distribution
over an infinite time is the definition of "random".