It's funny how one can take a simple problem and make it sound complicated.
Suppose I have a box that is sealed shut. I assert that the inner walls of the
box are painted red. Is that true or false? As long as the box is sealed, it
is "fundamentally undecidable" except to the ones who sealed the box.
I think it is stretching it to call this a violation of the law of the excluded
middle. It is simply unknown.
Now more to the point, I think Carl Sagan, Jill Tartar and the other ET hunters
probably believe that they would recognize an 'intelligent' signal when they saw
it, because they themselves have devised such signals with the intention of
communicating to others. They make them simple, but not repetitive, with
patterns that might correspond to something universal, such as the hydrogen atom
Balmer series, etc. Others have suggested using sequences of prime numbers.
There is a long history of literature on this question, which arose long before
there was any technical means like SETI. Similar problems arise in cryptography
theory, I imagine.
Paul Arveson, Research Physicist
73367.1236@compuserve.com arveson@oasys.dt.navy.mil
(301) 227-3831 (W) (301) 227-1914 (FAX) (301) 816-9459 (H)
Code 724, NSWC, Bethesda, MD 20084