Good Job Templeton

Whatever else the Templeton Foundation may have done wrong, they have done very right by funding the research behind two new papers, to appear in the Astrophysical Journal. The first paper reviews what evidence of aliens we should expect to see:

We motivate the \^G infrared search for extraterrestrial civilizations with large energy supplies. We discuss some philosophical difficulties of SETI, and how communication SETI circumvents them. We review “Dysonian SETI”, the search for artifacts of alien civilizations, and find that it is highly complementary to traditional communication SETI; the two together might succeed where either one, alone, has not. We discuss the argument of Hart (1975) that spacefaring life in the Milky Way should be either galaxy-spanning or non-existent, and examine a portion of his argument that we dub the “monocultural fallacy”. We discuss some rebuttals to Hart that invoke sustainability and predict long Galaxy colonization timescales. We find that the maximum Galaxy colonization timescale is actually much shorter than previous work has found (<109 yr), and that many “sustainability” counter-arguments to Hart’s thesis suffer from the monocultural fallacy. We extend Hart’s argument to alien energy supplies, and argue that detectably large energy supplies can plausibly be expected to exist because life has potential for exponential growth until checked by resource or other limitations, and intelligence implies the ability to overcome such limitations. As such, if Hart’s thesis is correct then searches for large alien civilizations in other galaxies may be fruitful; if it is incorrect, then searches for civilizations within the Milky Way are more likely to succeed than Hart argued. We review some past Dysonian SETI efforts, and discuss the promise of new mid-infrared surveys, such as that of WISE. (more)

The second paper describes a plan to look for some key evidence:

We describe the framework and strategy of the \^G infrared search for extraterrestrial civilizations with large energy supplies, which will use the wide-field infrared surveys of WISE and Spitzer to search for these civilizations’ waste heat. We develop a formalism for translating mid-infrared photometry into quantitative upper limits on extraterrestrial energy supplies. We discuss the likely sources of false positives, how dust can and will contaminate our search, and prospects for distinguishing dust from alien waste heat. We argue that galaxy-spanning civilizations may be easier to distinguish from natural sources than circumstellar civilizations (i.e., Dyson spheres), although Gaia will significantly improve our capability to identify the latter. We present a “zeroth order” null result of our search based on the WISE all-sky catalog: we show, for the first time, that Kardashev Type III civilizations (as Kardashev originally defined them) are very rare in the local universe. More sophisticated searches can extend our methodology to smaller waste heat luminosities, and potentially entirely rule out (or detect) both Kardashev Type III civilizations and new physics that allows for unlimited “free” energy generation. (more)

I’ll be quite surprised if they see anything, as I find hard to believe that, if they have existed nearby for a billion years, aliens wouldn’t already be plenty visible in their first result. But the issue is plenty important enough to look carefully anyway.

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    Was this post inspired by Dan Browne’s comments on the lumpy filter post (which also seemed to be about Dyson Sphere-type stuff detection efforts)?

  • Why isn’t this one of those questions that should be postponed, so that future mankind has a raison d’etre?

    • Siddharth

      Probably because this has bearing on existential issues. We want to get a sense of the structure of the Great Filter.

      • That’s probably it, although I think the problems of cosmic origin are more inviting than weak existential inferences. And both are only of symbolic significance.

  • Cahokia

    A mission to Europa could provide evidence of whether the filter operates at the lowest level – the development of unicellular life.

    If there’s a briny ocean in Europa and no life is found, it could indicate, along with Mars, that even simple life is very rare.

  • Siddharth

    Do you have an explanation for why this question, which seems to bear significantly on the issue of Our Place in The Universe, doesn’t attract much attention?

    • Cahokia

      The logic underlying this question is too obscure.

      You’d have to explain to people the staggering time scales involved and how even at slow rates of expansion extraterrestrial civilizations should be visible by now.

    • Salem

      Most people, for understandable reasons, think it overwhelmingly likely that we are alone in the universe. Therefore questions of the form “Assuming there are alien civilisations out there, how come we don’t see any?” don’t strike most people as the least bit interesting.

  • Dan Browne

    I can’t find the link, but I’m pretty sure I read they had found some interesting objects that may fit the category and which need to be ruled out. It appears that it may be difficult for life to get started and also difficult for life to reach intelligence but we have the example of us right here. Even if we are the only ones in this galaxy it’s still plausible by the mediocrity principle that we could predict at least one intelligent industrialized civilization per galaxy, so this is pretty exciting stuff.

  • At first I thought this was connected with Brad Templeton, who has spoken at the Singularity Summit on automated car traffic systems. Still, very cool.