Received: by alpheratz.cpm.aca.mmu.ac.uk id PAA23638 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Wed, 17 Jan 2001 15:03:05 GMT Message-ID: <A4400389479FD3118C9400508B0FF230010D1A43@DELTA.newhouse.akzonobel.nl> From: "Gatherer, D. (Derek)" <D.Gatherer@organon.nhe.akzonobel.nl> To: "'memetics@mmu.ac.uk'" <memetics@mmu.ac.uk> Subject: RE: DNA Culture .... Trivia? Date: Wed, 17 Jan 2001 15:58:32 +0100 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain; charset="iso-8859-1" Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
Vincent:
Or, in other words, what kind of information could be bereft of
meaning?
Derek:
In information theory, informational entropy is defined as H =
sigma(-xlog2x) where x is the frequency of a token, symbol or event. A
random series of n events (or a gibberish text of n symbols) will have high
informational entropy H as all xs will be near enough 1/n. Where one or
more symbols are overrepresented relative to the others, or the series of
events are not random, the value of H will be smaller. You can therefore
predict if a phenomenon is likely to contain information without knowing its
meaning. Thus a message from an extraterrestrial civilisation might be
recognisable as such without having a clue as to what it is about.
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