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New Earths: A Crossroads Moment

A symposium called Crossroads: The Future of Human Life in the Universe seems timely about now (the site has been down all morning but should be up soon). With the Kepler mission undergoing calibration and CoRoT actively searching for small extrasolar worlds, we’re probably within a few dozen months of the detection of an Earth-like world around another star (and maybe, by other methods, much closer). This is sometimes referred to as the ‘Holy Grail’ of planetary sciences, but as soon as we accomplish it, a new ‘Grail’ emerges: The discovery of life on these worlds. And then another: Finding intelligent life.

We can kick the Fermi Paradox around all day, and enjoyably so because it forces us to use our imaginations, but ultimately we hope to put together the hard data that will tell us which of our speculations is most accurate. I see that the Crossroads symposium, which will take place May 1-2 as part of the Cambridge Science Festival, will include Frank Drake’s re-examination of his famous Drake Equation, but will also question whether crisis points like exhaustion of our natural resources may be the kind of ‘filter’ that any intelligent species must overcome.

Chokepoints for Technological Cultures

That’s a good Fermi solution if you posit the emergence of a million technological civilizations in our galaxy, as Carl Sagan once did. Those of us who think intelligent life is rare see no real contradiction in our lack of observed neighbors, but where are all those highly adapted technological cultures otherwise? Thus the plausibility of the doomsday hypothesis: Getting through that phase when a society is capable of destroying itself may be too high a hurdle for most to overcome. There are other forms of cultural collapse, too, as our own experience with the fragmentation of Roman culture in the 5th Century and later makes clear.

Then again, maybe that ‘great silence’ is only a transient phenomenon. Yesterday I talked about Seth Shostak’s new book Confessions of an Alien Hunter, and because it’s germane to this discussion (and sitting right here on my desk), I’ll return to it. Shostak notes that ever more powerful computers are ramping up SETI’s powers to the point that by the year 2030, the Allen Telescope Array ought to be able to check for signals in the direction of a million or more star systems. He points to Sagan as well as Frank Drake’s estimate of 10,000 communicating civilizations in examining the implications:

That’s enough to offer success if Drake is correct. If Sagan’s right, a signal will be found sooner. In other words, either we will discover evidence for ET within the lifetime of the present generation or we’ve erred badly in our presumptions.

Moore’s inexorable law thus makes our generation possibly the first with a real chance to witness that detection. The pace of change in digital technology seems inexorable. By 2020, a desktop computer should have the computational capabilities of a human being. Will we have something — electromagnetic leakage, a beacon, a directed transmission — by then?

A Machine on the Line

Assuming we are indeed at that crossroads the symposium notes in its title, it’s also plausible to speculate that another key filter is the development of artificial intelligence. If we do go through a ‘singularity’ event and our intelligent equipment begins to evolve on the fly in directions we cannot imagine, it’s more than possible that any SETI signal we receive is going to come, as Shostak notes, from a machine. All of which has ramifications for where we look for a signal:

Serbian astronomer Milan Ćirković has suggested that the best location for cerebrating hardware would be the outer fringes of the galaxy. In those godforsaken neighborhoods, where temperatures are colder than dead penguins, energy-consuming machinery could run most efficiently. That’s basic thermodynamics. But while Ćirković’s argument has its appeal, the galactic boondocks might be too dull for big brains with semi-eternity on their hands. They might prefer to exchange thermal efficiency for the opportunity to be situated closer to the galaxy’s central regions, where there’s a lot more astronomical action.

But then, if we’re truly dealing with machines at this order of complexity, it’s clear that our ability to gauge their intentions is going to be minimal. A crossroads indeed looms ahead as we ponder all this, hoping to hear a signal from another star system, wondering whether Earth-like worlds are indeed as common as some have come to believe, and speculating on the survivability of a nuclear-tipped species like our own whose digital tools may one day be beyond our ability to control. All good reasons to check out this symposium, which will be available as a Webcast.

Comments on this entry are closed.

  • Ron S April 16, 2009, 16:07

    A key difficulty with the SETI ‘lottery’ is that we don’t know the odds of winning. Do we buy 1 ticket? 100 tickets? 10,000 tickets? Just how many tickets should we buy to have some reasonable probability of winning? We don’t know.

    For that reason, while it is undeniably more likely that we’ll succeed for every increase in our search capability, I do not believe it is justified to declare that at this point in time that success is “just around the corner”. So are fusion and AI, just as they have been for many decades.

    I am not trying to throw a wet blanket on SETI – I want the effort to be expended and would love to see success in my lifetime – but I don’t think we have reason to suddenly become terribly optimistic. This is something that we need to stick with for the long haul and, like with manic-depression, we need to smooth out the high and low emotional extremes if we are to keep at it consistently over the many years (or decades) that it may require.

    Maybe if we fail at the search for long enough, ET will lose patience with us and leave a comment in this blog.

  • Administrator April 16, 2009, 16:25

    Ron S says:

    Maybe if we fail at the search for long enough, ET will lose patience with us and leave a comment in this blog.

    More likely, though, on Allen Tough’s site ;-)


  • Mark Phelps April 16, 2009, 21:05

    Hi Paul, yes interesting times,the first light from Kepler is up at Spaceref.com…
    very cool and a bit humbling to see so many stars flooding the image…..Dave Poole any one?. Re the comment on where to look ie outer rim, Dyson has a paper some years ago about what to do,life that is, if the Universe was open….he covers looking for places that are very cold an suggested how even in deep intergalactic space ‘creatures’ could exploit temp variations….I can not find it but will post the ref when I do. Also I find it hard to see how a tech civilization could exhaust the natural resource base,far too much ‘stuff’ in the solar system or any solar system to worry about overuse….unless ‘political’ considerations have greatly curtailed access to the space environment. With respect to Earth it seems that the politica, national security objections to moving a large resource rock in close to the Earth will mandate operations out in deep space or perhaps a range of ‘industrial’ orbits.
    A civilization that stays on planet will be a bit,looking for a proper term but the nature of space allows a range of industries that are not planet friendly….unless they are all pastoral in appearance only,the high tech hidden away…..not a new theme in scifi….

  • bigdan201 April 16, 2009, 23:47

    Who knows what sort of ET life is out there. Im pretty sure that primitive life is not uncommon, and on some worlds there may be complex life (plants, animals, etc). Intelligent life is probably not common.. however i cant say it doesnt exist. if there were only 2 or 3 forms of intelligent life per galaxy, there would still be many in the universe.

    ive always had some doubts about the SETI program, but i heard about one interesting incident about whats called the wow! signal. apparently there was a very high intensity electromagnetic reading in the 1970s, which hasnt been found again. makes you wonder…

    Still, im not overly optimistic about finding advanced ETI, although its good to keep looking and not ignore the possibility. Hopefully, the SETI program and its data can and will be used for other scientific reasons.

  • observer April 17, 2009, 4:00

    Some no-great-filter solution for Fermi paradox was indirectly provided by Jacek Dukaj’s SciFi novel “Perfect Imperfection”


    briefly speaking progress of civilizations can lead us to the place where no direct radio contact is needed any more

  • ljk April 17, 2009, 9:54

    For those who have “doubts” about SETI, my response to that is
    this: What is your alternative to searching for other intelligences
    in the Universe?

    Considering the relatively short time humans have been doing
    SETI (50 years – mostly sporadic with just a few methods – in
    a galaxy 10 billion years old) plus being stuck having to conduct
    it from the vantage point of one planet, it would have been very
    lucky for us to detect a signal by now.

    Are you implying that we should not bother at all if we can’t
    zip out to each star system with an FTL vessel? Should we just
    sit back and wait for ETI to come to us, hoping that in a galaxy
    of 400 billion suns 100,000 light years across that Earth and Sol
    will somehow grab their attention and interest in such a journey?

    I am glad to see that SETI is finally getting some real respect
    after being treated like an embarassment for decades by the
    mainstream science community, but this just means that the
    real work to find alien intelligences is only now truly beginning.

    Grabbing a few hours here and there on various radio telescopes
    has been little more than show, though the public tends to think
    SETI is one giant monolithic entity that has been scanning the
    skies 24/7 for years – which it definitely is not and has not.

    While a targeted transmission would be very nice, of course, I
    think the best we can hope for when it comes to SETI is grabbing
    a random signal meant for others that we just happened to
    intercept by chance.

    Of course there may be a society spraying a general Hello message
    all over the galaxy, hoping to get someone’s attention, but you have
    to ask why would they do this? Are they just terribly optimistic and/or
    nieve? Are they trying to stir up the bushes to see what comes out
    and then get rid of potential competition?

    Unless there are societies out there that are either totally secure
    in their security or have no fear, the one scenario where I can see
    an ETI beaming their information into the unknown is the civilization
    that discovers it is about to become extinct with no hope of rescue.
    Such a society might want to preserve itself by giving all that it was
    and knows to potential others who might save it in their efforts to
    understand who these beings were. James Gunn’s 1972 SF novel
    The Listeners has this very scenario.

    Observer, thanks for the pointer to author Dukaj. It looks like
    Poland may be producing another Stanislaw Lem. Too bad his
    work isn’t in English yet.

  • ljk May 14, 2009, 10:02

    May 13, 2009

    A New Drake Equation? Other Life Not Likely to be Intelligent

    Written by Nancy Atkinson

    Looking for signals from distant civilizations might be an effort in futility, according to scientists who met at Harvard University recently. The dominant view of astronomers at a symposium on the future of human life in the Universe seems to be that if other life is out there, it likely is dominated by microbes or other nonspeaking creatures.

    Speakers reviewed how life on Earth arose and the many, sometimes improbable steps it took to create intelligence here. Radio astronomer Gerrit Verschuur said he believes that though there is very likely life out there — perhaps a lot of it — it is very unlikely to be both intelligent and able to communicate with us.

    Full article here:


  • ljk June 15, 2009, 22:45

    Detecting planetary geochemical cycles on exoplanets: Atmospheric signatures and the case of SO2

    Authors: L. Kaltenegger, D. Sasselov

    (Submitted on 11 Jun 2009)

    Abstract: We study the spectrum of a planetary atmosphere to derive detectable features in low resolution of different global geochemical cycles – using the sulfur cycle as our example to derive detectable features for first generation space- and ground- based telescopes that will characterize exoplanets.

    We assume that the surfaces and atmospheres of terrestrial exoplanets (Earth-like and super-Earths) will most often be dominated by a specific geochemical cycle. The sulfur cycle driven by outgassing of SO2 and H2S followed by their transformation to other sulfur-bearing species is clearly distinguishable from the carbon cycle which is driven by outgassing of CO2.

    We calculate planetary emission reflection and transmission spectrum from 0.4 to 40 micron with high and low resolution to assess detectable features for current and Archean Earth with varying SO2 and H2S concentrations.

    We find specific spectral signatures that are observable in a planetary atmosphere with high SO2 concentration. Therefore future measurements can potentially distinguish planets dominated by a carbon or a sulfur cycle.

    Comments: 8 pages, 6 figures, ApJ submitted

    Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

    Cite as: arXiv:0906.2193v1 [astro-ph.EP]

    Submission history

    From: Lisa Kaltenegger [view email]

    [v1] Thu, 11 Jun 2009 19:59:49 GMT (394kb)