So, don't be disappointed, the project is going to take some time.
The universe
is a REAL BIG place.
Well, I'm not really hopeful that anything will be found. Information
theory says that an optimally encoded signal is indistinguishable
from noise, unless you have the decoding key. We have been sending
easily intercepted and understood un-encoded signals into space for
some 100 years, but only for about 40 years at the frequencies at
which SETI@Home is listening.
We are already beginning to encode signals in both time and frequency
in a way that would make them unintelligible to an alien running the
SETI@Home software. Digital cell phones, and soon, digital TV are a
few examples. Wireless datacom uses "spread spectrum" techniques that
render a signal almost impossible to even detect without the same
frequency-hopping algorithm.
Take a digital image, for example: a pattern of "ones" and "zeros"
that anyone can recognize as a signal. Now save it as a JPEG, or even
an LZW TIFF. Clip a bit out of the middle -- think we're going to be
lucky enough to intercept the few parts per million of un-encoded
header information? This compressed segment is totally meaningless.
Convert to analog and play through a speaker and it will sound like
noise.
Take digitized sound -- again, a nice pattern, recognizable as an
intelligent (well, with the possible exception of Rap music or Nixon
tapes :-) signal. Now encode it as an MPEG Level 3 file (.MP3 for
those using systems that still don't know the difference between a
name and a type) -- once again, noise, unless you have the decoding
key.
I think we have perhaps 100 years maximum in which to "catch" a
civilization -- after they have begun to use electromagnetic
technology, but before they have moved past it. There may be plenty
of civilizations out there, but how many of those will be precisely
in the window in which they are using technology we currently
understand and can intercept?
(But I've been running SETI@Home anyway -- a PowerMac G4 does a set
in under 10 hours, and it looks cool to people dropping in, and who
knows... :-)
--
: Jan Steinman <mailto:Jan@xxxxxxxxxxxxxx>
: Bytesmiths <http://www.bytesmiths.com>
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