posted on Dec, 23 2010 @ 09:45 AM
SETI is, literally, looking for a needle in a haystack. Or, more accurately - it is looking for a vaguely described "object of interest" in a
massive pile of odds and ends taken from people's homes. We have no real clue what we are looking for. In all honesty - the signs of our own
civilization are fuzzed over the course of just a few light years - barely above the radio background. About the only thing likely to grab attention
outside of several light-years would be our nuclear tests - and even these have only likely been picked up (via known methods) by systems within 30
light-years, or so. Even if they had the ability to travel faster than light, they would still have to wait for our own signs of existing to be
At that - most of our nuclear explosions were so brief that most of our own equipment would be unable to pick them up - designed to pick out signals
over the course of weeks to get such sensitive readings. A momentary burst would need to be insanely intense and/or focused to register.
While they may be all-knowing and god-like ET, I'm not so convinced. Even given a thousand more years of development at our current pace - we would
be far from omniscient or omnipotent. Given a few million more years - it's hard to speculate - but I doubt technology would have evolved so
radically as to permit omniscience.
We must then look at what types of civilizations we would be looking to find. The first category would be other civilizations like ours. It would be
rather pointless to try and find a species using completely different concepts of technology and communication, as we wouldn't know what to look for
or how to interact. So - we'd be looking for signs of what we recognize as technology and be open to expanding that search as our own technology
develops. This would be electromagnetic radiation.
Lower-frequency (LF and ELF) are rather common and a generally bad thing to try and use to communicate. It is, however, one of the primary markers of
our own civilization - millions of kilometers of wiring emitting between 50 and 80 Hz. Since a civilization is likely to use this for some time and
it is likely to persist - it makes it a valid search criteria.
HF is more frequently used in communication - but is generally low power and has difficulty with the ionosphere. There are also a number of HF
background sources that could throw this off. It would, therefor, be somewhat more telling - but also somewhat more fickle of a source.
X and Gamma rays would be more ideal. The energy-waves, themselves, are more intense and more likely to be distinguished against the background.
Many sources of gamma rays are noted and documented, so a 'new' source displaying a repeated pattern or exhibiting unique behavior would be -very-
telling of some form of advanced civilization. Unfortunately - most sources of such intense radiation as we use them are weaponized forms. Our
civilization does not routinely emit gamma or x-ray radiation in any regular interval or background operation to such a degree as it might be detected
by another civilization. It would not be logical to presume other civilizations would do so, either.
Thus - gamma and X-ray interceptions would likely indicate an actively-pinging system, or some kind of nuclear war (or some other purpose for nuclear
warheads that our species simply doesn't relate to).
This leaves light-based communication - which is along the lines of gamma and x-ray... we don't emit tons of light that could be detected outside of
our own solar system. It -might- be possible with a large-enough array to detect such things as city lights on our planet from a few hundred
light-years away... but it would be a colossal array of unimaginable proportions - something we might consider building in a hundred years or more.
Of course - by then, we may have broken away from relativistic restrictions and find it better to simply jump to another system and have a look around
the old fashioned way.
Which brings us to the other type of civilization we would be looking at trying to contact/detect: - an older civilization and/or one that is
sufficiently more advanced than ours. It is entirely possible that a species could go about propagating the galaxy without overcoming relativistic
limitations on velocity - so they do not have to be advanced in the sense of being able to warp around. However - such species, if they have the goal
of searching for and making contact with other species, would likely go about setting up automated 'buoys' set to search for various activity. By
keeping track of where they have buoys, when a buoy receives something of interest, it forwards the information back home - perhaps via a relay system
(contacting other buoys). In this way - communication is still limited to the speed of light, but many of the problems associated with searching for
intelligent life are eliminated - such as where to look for signals (the buoys look everywhere to the best of their ability and phone-home with
concentrated pre-defined beams), and compensating for the inverse-square law (it would be far more practical to detect our civilization from a buoy
placed on, say, the moon or Mars, than it would be to detect it from Betelgeuse).
A civilization having overcome relativity would likely employ a similar system, just be far less restricted.
Detecting these civilizations still falls within our known concepts of technology. If they have moved on to using other forms of technology - it
would be virtually impossible for us to look for them, as any signs they exist would be almost indistinguishable from natural phenomena or nearly
impossible for us to predict how their technology may work - much less how to detect it.
Would a man, born and raised in the remote tribes of South America, regard the regular transcontinental flight overhead (visible from his perspective)
as anything of intelligent or technological origin? It's happened since the day he was born and will continue beyond the day he dies.
Likewise - we are in a similar situation when dealing with sufficiently advanced civilizations. If we don't know to recognize it as the product of
technological origin - then we can't search for it. We, thus, have to look for emissions in the electromagnetic spectrum.
An advanced species may actively signal in these ranges, particularly if they are experienced in dealing with other species and societies that develop
technology similar to our own. Or, they may know we are already here. We can speculate on it until we are blue in the face. At the end of the day -
we don't know how to search for anti-gravity, "FTL-wakes", or "superluminous emissions" - Even if we developed a method of accomplishing it -
there may be many other methods that leave completely different indicators in utilization by other species.
So, yes, there are plenty of "flaws" in trying to search for another intelligence and/or society. In all likelihood, we will be 'warping' or
'jumping' off to other systems in search of life before SETI ever gets a positive result. However - it can't really hurt to try.
That poses an interesting concept, however. We have spent, roughly, a hundred years in the semi-modern electrical era. That's a rather short
time-frame, cosmologically speaking. Determining how long a species is likely to remain in any given 'state' of technology is impossible given our
lack of data - but even if we were to be pumping out radio waves for a thousand years - that gives every other species a thousand-year window to
detect us; plus relativity constraints. It is quite likely that, within a hundred years, we will have some form of FTL capability. Even if it took
two or three hundred more years - that's still a 400-year window. By that time, it would be far more reasonable for civilizations looking for our
presence to watch for us to show up in their system and search around. We would be closer and looking for them, and any indications of our presence
would be far more noticeable than those of our home planet.
It would, perhaps in a strange bit of irony, be more worth-while for SETI to search for other civilizations to be perusing around our own back yard as
opposed to searching through countless star systems for faint signals of existence.
That is heavily weighted on the plausibility of relativity-defying drive systems - but from a statistical standpoint - it is far more likely that an
advanced civilization would be detected while visiting our system than we would be likely to detect their own planet. It is also far more likely that
they would be here than it is likely we would be listening to their neck of the woods during one of the "windows" in which we could detect their
I would still do both - you never know what you will find when you keep an open eye. However, if I had to choose one over the other (as one must
often do with limited funding) - I would choose the search for signs that an advanced civilization is or has been in our own back yard. If they are
that advanced and have a significant chronological lead on us - it is likely they've already been here and cataloged our planet's existence and
noted any interest in it. It would therefor be likely that they would return to observe - and therefor more likely for us to detect them. If no one
has been here, or has simply had the desire to return - it is still more likely that an advanced species would stumble upon us than we would be to
stumble upon a reliable indicator from a planetary system of a techno-industrial society.