Thu Oct 17 17:02:00 EST 1991

The premise is, in fact, similar to that of the science fiction novel
"Andromeda Strain".

With DNA's 2 bits, unpunctuated, per base, an encoding of PI might proceed
in this way:
 (1) establish order and frame
 T C A G T T C A G T T C A G T
 (2) begin message
 G T A C T C ... (to five decimal places)

A non-repeating message, like PI, could easily be mistaken for noise
(complexity theory).  An more easily recognizable message would repeat or
otherwise exhibit patterns.
 T C A G T T C A G T T C A G T T T T T T T T T C T C T C T T T C T
 T T A T A T A T T T A T T T G T G T G T T T G T C T C T A T
 C T A T G T A T C T G T C T G T C T T G T C T C T T ...

I believe some Ozma, Explorer and Voyager messages have tried to encode bit-map
pictures based on prime number sized arrays.  These were simple 2-dimensional
arrays that would hardly show up on a low-resolution monitor.  Today they would
probably make 439 x 1021 pictures.  But why not 3-D arrays showing something
like a human body, or 4-D and let it wave its hand.

A more informative message would perhaps assume that a compatible biochemical
soup existed at the destination (that is, that the DNA would be translated to
RNA) and would set out the plans for an RNA machine that, perhaps among other
things, went about reproducing the message.  It would look like a virus with no
protein dependence.  At this point I will defer to Tom Schneider for the
construction of such a molecular machine.

                                 Dr. John S. Garavelli
                                 Database Coordinator
                                 Protein Identification Resource
                                 National Biomedical Research Foundation
                                 Washington, DC  20007
                                 POSTMASTER at GUNBRF.BITNET

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