archive: Re: SETI modulation of ETI transmission

Re: SETI modulation of ETI transmission

Jim Glover ( )
Fri, 28 Aug 1998 12:38:55 -0500 (CDT)

Matthew G Cheung <> had posted:

> >I was just wondering, if there are 100s of ways to modulate a signal,
> >then who knows if we'll ever find an ETI signal? What seems logical to
> >us and what we use maybe far off from what ETIs will use. Similar
> >statements have been made before about how ETIs probably won't think like
> >us. They could use phase modulation or something like that, and as I
> >understand it, you wouldn't be able to recognize it without a phase
> >correlator. (Lee Kitchens) responded with:

> Matthew, you are probably right about the modulation problem, and I think
> it is expected. Once the league has an ETI carrier signal, work can begin
> to demodulate.

And now, my 2 cents' worth:

I believe that Matthew's concern is not that we might find a signal
we couldn't make any sense out of, but rather, that we might fail to
detect the presence of the signal in the first place, because of it
being so different from what we're looking for.

I think I'll take a moment to digress by introducing myself, so that
those of you who wish to do so, can consider my lack of credentials,
and the bias that one of my strong opinions about SETI in general
lends to the discussion at hand. I've been interested in radio since
I was a teenager, first licensed as a ham in 1976. I originally
pursued a major in EE, but switched to computer science when I
realized that a career in the blossoming computer field would give
me more choices about places to live, etc. Before I made that career
decision, I'd hoped for employment which would involve me in radio
communications. My fondest wish was for professional involvement in
SETI. I am quite pleased to find that since I've abandoned that wish,
things have taken a turn which puts amateurs in perhaps the best position
of all to do SETI research. (Note: I'm not pleased that public funding
has evaporated; I am only pleased that that problem produces such a
pleasant opportunity for those of us who might like to try SETI

Throughout much of my adult life, I've allowed other considerations
(career, school, the objections of my first, now ex, wife, etc.)
limit my involvement in amateur radio to occassional exchanges on
2 meters. Lately, I have been rejuvenating my old interest, and
am pleased to find that it re-ignites easily, and passionately,
including my fascination with SETI. However, I'm addressing other
amateur radio priorities first (getting involved with building,
HF, etc.) and am a long way from a point of being ready to devote
considerable resources to a listen-only aspect of the hobby. For
now, SETI is an armchair pursuit, for me.

In listening to conversations about the likelihood of our finding
signals (or other evidence of ETI), I often find myself suspecting
that we tend to over-estimate the extent to which our own assumptions
about how things might be done might be universally applicable. This
is, after all, only natural for us. We tend to brush aside wisdom
such as "A thing is only impossible until it is possible" when we
try to assess how other intelligent beings might behave. We make
guesses about what their values and motivations might be, little
mindful of the fact that the very concepts of "values" and
"motivations" might be so foreign to some ETI that they might have
trouble comprehending what we mean by them. Now, don't get me
wrong--I don't think anyone's failing to think clearly about this,
or anything. I think we simply do what we can, to try to guess
what would be feasible, or likely, and what would not. However,
we necessarily do so from our own, somewhat limited point of view,
and I just think that it's inevitable that our bottom line ends
up skewed by that--and probably, almost always in favor of
over-estimating the extent to which ETIs might resemble us.

Now, specifically-- who says you have to have a carrier wave? We
are in our RF infancy, as a society (in the cosmic, billions of
years, sense) and already, we find ourselves developing radio
communication techniques which in some way, to some extent, stray
away from the idea of pouring energy into a carrier wave which
serves little purpose other than to establish our foothold on
some particular frequency. Perhaps it exhibits a bit too much
of the "of course, they'll have to be much like us" thinking,
to assume that there will be a carrier wave at all.

Meanwhile, I continue to be thrilled at the idea of looking for
the types of radio emissions we'd be capable of detecting. I
just think that we increase the accuracy of our thinking (for
whatever that might be worth) when we keep a healthy respect
for the fact that a whole lot of whatever is going on out there
in the universe may be so different from what we might expect,
that we'd have a hard time recognizing it as being evidence of
ETI, even if it were. The idea that there might be radio
communication which we'd fail to detect at all because it
doesn't fit the model we're using to search for it doesn't
strike me as unlikely, at all.

--Jim WB5UDE