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Fermi Meets Elsie: SETI’s New Conundrum

“Simple and cheap, like onion dip.” That’s how Seth Shostak (SETI Institute) refers to our early optical search systems, which have involved limited equipment in the hunt for extraterrestrial intelligence, at least when compared to the much more demanding resources deployed by the radio search. Cheap is good, but not when you can only check one part of the sky at a time. All this gets Shostak pondering in a recent article about the parameters of a laser signal from an extraterrestrial civilization.

For if we might miss a faint signal, what about a really big one? Suppose an intelligent species somewhere out there is deliberately trying to contact our planet. Wouldn’t it make sense, Shostak muses, to create a huge optical impression, a signal that would catch our attention so obviously that we could then focus in to detect whatever message might be streaming from that same location? Bright objects in the sky do appear and are usually recorded, as witness historical records of supernovae.

And so it may be telling us something that we have no records of recurring bright objects. Sure, it would take huge resources to make a signal from such a civilization bright enough for the average person to see it without any equipment (Shostak estimates 5 X 1025 watts to push such a signal from 1000 light years away). That’s well beyond our resources, but not those of a Kardashev Type II civilization (one capable of using the entire power output of its Sun), which could imply there is nothing more advanced than a Type I civilization near us.

But whatever its Kardashev type, an advanced civilization may have no interest in beaming a signal to us in the first place. Or perhaps we remain simply undiscovered in a galactic backwater. Whatever the case, ‘naked eye SETI’ adds another twist to the ‘where are they’ question that Fermi posed, and at least seems to be saying that if a Type II culture wanted to reach us, it could have made its presence so blindingly obvious that we would be sure not to miss it. “…it strikes me as paradoxical,” says Shostak, “given the vastness of the cosmos, that such a simple signal has not been recognized, a signal that even a cow could see.” Welcome to the ‘Cow Paradox.’

Centauri Dreams‘ take: Long-time readers know I think there are few technological civilizations in our galaxy to be detected. When asked, I always settle on a number like 5-10 instead of Sagan’s 1 million. That’s the thought of a writer with no scientific qualifications other than a keen interest in these topics. But we’re all just guessing at this point, and this writer is not at all surprised our SETI efforts have so far come up short.

Comments on this entry are closed.

  • Edg Duveyoung December 21, 2006, 14:06

    Ain’t it fun to think without having to consider how hard it would be to manifest it? I feel like Fred Flintstone creating a car with the materials-at-hand. 200 years from now, who knows what will have been discovered to obviate the need for a Dyson Sphere or any of the imaginings of today’s best thinkers.

    So, without having to prove anything or even to have a “reasonable grasp of physics,” let me have some of this very fun.

    The Drake equation spreads out all the ways that a star could be considered “civilization free.” We’re always left with every speculation pretty much tossing out just about all the stars as candidates for harboring life.

    Which means?

    There’s stars galore to use as raw materials.

    First let’s put aside the wonderful concept that Allen Watts first taught to me — that if we saw our earth 5 billion years ago, we would have said, “Sniff, nothing alive here, this is a dead world.” But come back later and we discover that the earth was “rocks that give birth to people” after all.

    Great concept — life could come from anywhere.

    But who cares if we waste a few billion star systems that are lifeless-now! Let’s not get into any issues about “stem cell” research and wring our hands in concern about the life “that could be;” let’s use them! After all, aren’t the stars themselves simply “wasting” all that fuel to produce all that light “for nothing?” Colossal wastes they be while they’re waiting for life to pop out of them.

    So here’s the question. How hard would it be for earth science-100-years-from-now to create a self-replicating nanobot that builds a Dyson shield? Just sprinkle some nanobot dust on near-by star and watch as a shield forms as all the dust etc. is collected and used as building material. Now imagine that instead of that shield being used for gathering the star’s energy, but instead is merely to be a “sun shade.” Low tech. And now, take another step and imagine that the shield is a hemisphere that revolves around the star — not an entirely enclosing sphere — sorta like the half finished Death Star in the Star Wars film.


    A shadowhouse is formed. Not a lighthouse sending out a beam, but instead, a star that sends out a non-beam, a long shadow. The star would blink at us as if it were a lighthouse.

    This is just a mechanical shade. You don’t have to process the star’s energy and turn it into a massive laser beam. All the stars that we see have managed to get their photons to us, right? Pretty basic communication but effective.

    So here’s this star shade that revolves. The blinking gets attention — from anyone who could see it before it was semi-shaded.

    And now the final step: the starshade can have “holes in it” that are shaped like, well, WORDS. If you see a blinking star, look at the shadow closely, and see if you can’t see a very faint message “printed” on the shade.

    The shield could be encoded to have, well, ALL KNOWLEDGE printed on it, and all that would be necessary would be to have telescopes sensitive enough to read the “fine print.” So we’d have a METI star, a shadowhouse drawing the attention with silences, and then the subtler message that is “eternally” there.

    We all know that singularity is approaching. A nanobot that could do the above is just around the corner. We could be broadcasting “all human knowledge” on that shade by, say, circa 2206, eh?

    Maybe the shade could be like a giant DVD, and all one would have to do is “read one single longitudinal line at a time” of the shade as it passes in front of the star.

    The shade could be a movie on the half shell!


  • ljk December 21, 2006, 14:12


    * How Much Does SETI Require Robots?

    In each artificial life creation story, there is always a cautionary line –
    questioning the right of humankind to create a consciousness that would
    otherwise not be present in our universe. Let us inspect that theme
    philosophically to gauge its true value to us today.


  • JD December 21, 2006, 14:14

    I mostly concure though I think you’re a bit optimistic in your count. My own opinion is created by simple probabilities. I can agree with many of the reasons given, by others, as to why advanced technology civilizations would be unobservered or even reclusive. Having said that there would still be a percentage that would consider it a mandate to contact others or would have some social or racial imperative to “go a vikining” if they had the tech to do it. Therefore where are the explorers, merchants, missionaries, colonizers or conquerers?

    The thought that all species would be cooky cutter coppies of each other is the hardest thing for me to believe. If advanced tech civilizations have developed over the past dozen galactic rotations there would be at least one to break the mold of reclusiveness and reach out for good or ill.

  • ljk December 21, 2006, 14:49

    How long would it take to explore and colonize 400 billion
    star systems, and would an ETI want to occupy and/or even
    let its presence be known in an already inhabited system?

  • Ron S December 21, 2006, 15:09

    I think all of this silence must be most aggravating to those who have a strong inclination to suspecting (or believing) that there is/isn’t ETI and that it is/isn’t likely to exhibit some selection or other of attributes.

    Near as I can tell, we haven’t even heard enough silence to effect a non-negligible negative indication of ETI. The signaling sample space of who, when, where, why and how is vast. Any assumptions I’ve heard to the effect of attempting to reduce the sample space, and thus try to raise a statistically-valid result, seem contrived and unjustified, in my opinion.

    So we go on listening, perhaps in new ways and in new directions, (such as the suggested bright strobe lights), trying to find a signal or to find significance in the silence. Today we have neither.

  • Zen Blade December 21, 2006, 20:58

    But… what if some “natural phenomenon” is actually an artificial phenomenon? Or what if a Civ decides to use a natural phenomenon as its signal—knowing that said signal will be seen and recorded by any other civilization that sees it… Not that I know what any of this would actually mean in the practical sense of “hitching a message to the signal”. However, there could be countless ways that an ETI could be trying to signal us and we just don’t see the signal/comprehend it.

    But the original author makes a good point… if there are ETI’s out there, and presumably they are doing today what they were doing yesterday, and the day before that…
    1. There’s noone nearby
    2. We still haven’t reached a level of communication that ETI’s use.

    When were those telescopes that can find earth-sized planets going to be ready again???
    -Zen Blade

  • ljk December 21, 2006, 21:41

    Here is a different type of Active SETI: Signalling the galaxy
    by placing large geometric shapes in front of a star.


    A large scale version of an old idea for contact the inhabitants
    of Mars by making huge geometric forms in remote places on
    Earth to show the Martians there is intelligent life on the third
    rock from the Sun.

  • Eric James December 22, 2006, 0:44

    We are but babes, crying out from the wilderness…

    Okay, too sappy. But the analogy makes sense to me. Were we an advanced species, would we be quick to let a newly arising species know of our presence, or would we wish to observe it for awhile?

  • Adam December 22, 2006, 7:55

    Hi All

    I’ve got to wonder if there’s but a brief window of observation where a civilisation will make its presence known and then vanish from view as technology changes. If the window is narrow enough then perhaps no one is interested in signalling across the light-years because the time-lag is too great. Perhaps we are on the verge of developing instantaneous quantum communication which allows direct communication between civilisations willing to wait for one end of the quantum telephone to reach them with its cargo of entangled particles.

    If such becomes possible then the time-lag objection to teleoperated space-robots vanishes and the whole solar system (and beyond) opens up to our ‘immediate’ virtual presence. We could work on Pluto and go home for lunch.

    Who then will be willing to wait for the “Dirac Radio” (James Blish’s name for it) phoneline to open up in other star systems?


  • andy December 22, 2006, 17:19

    And now, a very silly explanation of the Fermi paradox.

    If you sum together all possible signals, you end up with white noise. This explains why there are (apparently) not any alien civilisations around: Sagan was being pessimistic, every corner of the universe is occupied with alien civilisations broadcasting continuously, all unaware of each others’ existence, because there are so many that it all ends up as white noise. Logigcal conclusion: if we start a METI project the situation will only get worse.

  • JD December 23, 2006, 1:43

    “How long would it take to explore and colonize 400 billion
    star systems, and would an ETI want to occupy and/or even
    let its presence be known in an already inhabited system? ”

    My point was if technology using, spacefaring life was moderately common. If you postulate one or two super civilizations which have progressed beyond the use of normal material and the electromagnetic spectrum then all bets are off. Very little sign would be evident. If you had a spectrum of civilzations poking about at least a few, despite advancement, would leave markers we could detect.

    As far as the scope. Many postulate the use of self replicating probes. Such a civilization, given the will could have easily covered the entire galaxy in less than one galactic rotation with their remotes. If they had not advanced beyond the science fields we recognize certain engineering limits apply and would allow detection (boost phases of probes, deceleration, signal transmission, the basic requirements for X size of appendages to act as propulsion and communication and of course overall energy use). Such things would of course be of very advanced designs and very effecient but also detectable. Of course if the postulated super civilization had progressed beyond the use of the electromagnetic spectrum then all bets would be off.

  • pfdietz December 23, 2006, 9:45

    How long would it take to explore and colonize 400 billion
    star systems, and would an ETI want to occupy and/or even
    let its presence be known in an already inhabited system?

    Assuming travel at .1 c, steps 10 light years long, and a 500 year delay between the arrival at a system and sending out new colonization craft, it would take roughly 5 million years to colonize the galaxy. This is a couple of thousands times less than the age of the galaxy.

    This is just a restatement of the argument behind the Fermi Paradox. Would ETI want to colonize an already occupied system, you ask? Well, until very very recently, it wasn’t occupied.

  • Zen Blade December 23, 2006, 13:57

    Or would ETI be allowed to colonize any system with living organisms, period… others have mentioned this idea.

    -Zen Blade

  • ljk December 23, 2006, 22:50

    And what astronomer on Earth at present would dare to seriously
    consider to anyone outside of him or herself in private that a
    celestial phenomenon is anything but natural? Unless they were
    unconcerned about the derision of their colleagues and the loss
    of their position.

    Would an advancing ETI really want to colonize every corner of
    the galaxy even if they could? Is colonization a trait of all intelligent
    life? Or just us? Or have they colonized as much of the galaxy as
    they want and the Sol system just didn’t make the list?

    I seriously wonder if the current level of development of our
    species is capable and ready to understand and comprehend
    advanced ETI?

    Of course there might be lots of intelligent life in the galaxy,
    but we are the most advanced and everyone else hasn’t learned
    to leave their planet to any decent degree, let alone colonize
    other star systems.

    Then again, many stars are older than ours and there was a
    paper about how the average Earth type planet is 1.8 billion
    years older than Earth.

    See here:


    Can we possibly relate to or understand beings that far
    ahead of us? Would they need an entire galaxy to live?
    Or did they already move on to other galaxies and/or

    But still, we must search as best we can.

  • ljk January 15, 2007, 8:57

    The following news clip is from the very first issue of
    Cosmic Search magazine from 1979. You can find
    all 13 issues online here::


    Holography or 3-Dimensional Mapping of Entire Universe Possible with Bold Soviet Concept for Space Telescope

    In a recent report of the Academy of Sciences of the USSR’s Space Research Institute, 23 Soviet scientists including N.S. Kardashev and I.S. Shklovsky, have proposed a radio telescope of remarkable characteristics. The report entitled the “Infinitely Built-Up Space Radio Telescope” envisions telescopes up to 10 kilometers in diameter assembled from many smaller modules of 200 meter diameter. The problems of delivering, assembling and aligning the modules in orbit are discussed.

    It is further proposed that two or more such telescopes be arrayed as an interferometer with a 20 astronomical unit baseline. This would involve placing the telescopes at approximately the orbit of Saturn. With such an interferometer operating at wavelengths of a few centimeters the entire universe lies within what is called the “near-field” or “Fresnel zone” of the antenna. What this means is that, in principle, it would be possible to determine the distance, size and shape of every observable object in the universe, producing holographic or 3-dimensional figures of the entire cosmos. This proposal is a bold concept which indicates that radio astronomers are still far from the end of their tether.

    The authors of the report point out that such a system could also be used to advantage for the detection of extraterrestrial civilizations (SETI). For example, planets the size of the earth could be detected from their thermal radiation alone at distances of 100 light years and planets like Jupiter at 1000 light years. Artificial radiation might be detected at much greater distances, possibly bringing millions of planets within range.

    Diagram with article:


  • ljk August 3, 2007, 14:05

    Marvin Minsky’s thoughts on the Fermi Paradox at the
    Transvisions 2007 conference: