Monday, 1 February 2010

Looking for Ruins in the Cosmos

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Will SETI know alien life when it finds it? A few days ago I read an excellent paper by Richard A. Carrigan entitled, "Starry Messages: Searching for Signatures of Interstellar Archaeology (pdf)". The premise of the paper is that we can Search for signatures of cosmic-scale archaeological artifacts such as Dyson spheres or Kardashev civilizations (Kc) in our quest to discover life beyond our blue planet.

While the idea of looking for ancient planetary sized constructs of an alien culture far more advanced than ours is a worthy endeavor insofar as an alien culture of scale Kc:II-IV will indeed have an impact on the solar system or galaxy in which they reside. Is the assumption that they will create Dyson spheres or other Solar System and Galatic sized energy collection artifacts a real possibility? When we scientists make such assumptions are we looking outside the human box during the thought experiment that are utilized to develop these hypotheses? Can we assume that these other civilizations will think and develop in the same way that the humans of planet Earth have?

I don't believe that Kc:II+ will construct such large scale energy production platforms. At that level of intelligence they will have perfected a form of "table-top" fusion to meet their energy consumption needs. It might even be plausible that they have Anti-matter energy production. Either of these tasked to a singular large scale project would be more than enough to power said project. Both are also scalable up to and exceeding the output of a dyson sphere type construct. Furthermore we can't even be certain of their development of these forms of energy to meet their needs, as their 'energy' might take on a wholly new form that we have not even discovered yet.

Another artifact we could look for is the sublimation of entire planets for material resources. Consider that a giant gas planet made entirely of Hydrogen could be sublimated into just about any element needed for large scale projects. There is also the possibility that Kc:II+ might salt gaseous planets for this process. In either process the time for effect would certainly give us a window of opportunity in which determination could be assessed.

Carrigan's premise also engenders our external civilizations with absolute benevolence. What if some advanced civilizations are not benevolent and shield their galactic footprint so as to give them the element of surprise upon commencement of hostilites against benevolent civilizations? Likewise, benevolent civilizations would shield their artifacts from discovery for self preservation. What if they just don't want to be found?

I believe we would be wasting our SETI resources looking for the dyson type artifacts. Instead we should be looking, as the paper indicates, for stellar spectral signatures such as star salting or isotopic ratio inconsistencies using Annis' distribution models. Looking for signatures of nuclear waste would be inefficient also as the tell-tale signatures will be quite dim when compared to the radiation surrounding it and there is also the chance that cosmic background radiation and natural star decay will give false positives.

In Summary, we as humans have a tendency to commit research to a human centric view. In order to find off world civilizations we must break that habit and consider that these Kc:II-IV beings will not develop technologically as we have. Can we even begin to describe the artifacts of a civilization a thousand, ten thousand or even a million years more advanced than ours when we have not even catalogued 1/5 of our planet's flora, fauna or natural sciences?