Dyson sphere hunt using Kepler data

October 12, 2012
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A Dyson sphere under construction (credit: Steve Bowers)

Geoff Marcy has received a grant from the UK’s Templeton Foundation to look for Dyson spheres, Paul Gilster writes on Centauri Dreams, the news forum of the Tau Zero Foundation.

Freeman Dyson hypothesized the vast structures over fifty years ago that could ring or completely enclose their parent star. Such structures, the work of a Kardashev Type II civilization — one capable of drawing on the entire energy output of its star — would power the most power-hungry society and offer up reserves of energy that would support its continuing expansion into the cosmos, if it so chose.

Marcy’s plan is to look at a thousand Kepler systems for telltale evidence of such structures by examining changes in light levels around the parent star.

Interestingly, the grant of $200,000 goes beyond the Dyson sphere search to look into possible laser traffic among extraterrestrial civilizations. Says Marcy:

Technological civilizations may communicate with their space probes located throughout the galaxy by using laser beams, either in visible light or infrared light. Laser light is detectable from other civilizations because the power is concentrated into a narrow beam and the light is all at one specific color or frequency. The lasers outshine the host star at the color of the laser.

The topic of Dyson spheres calls Richard Carrigan to mind. The retired Fermilab physicist has studied data from the Infrared Astronomical Satellite (IRAS) to identify objects that radiate waste heat in ways that imply a star completely enclosed by a Dyson sphere. This is unconventional SETI in that it presumes no beacons deliberately announcing themselves to the cosmos, but instead looks for signs of civilization that are the natural consequences of physics.

Carrigan has estimated that a star like the Sun, if enclosed with a shell at the radius of the Earth, would re-radiate its energies at approximately 300 Kelvin. Marcy will turn some of the thinking behind what Carrigan calls ‘cosmic archaeology’ toward stellar systems we now know to have planets, thanks to the work of Kepler. Ultimately, Carrigan’s ‘archaeology’ could extend to planetary atmospheres possibly marked by industrial activity, or perhaps forms of large-scale engineering other than Dyson spheres that may be acquired through astronomical surveys and remain waiting in our data to be discovered. All this reminds us once again how the model for SETI is changing.

For more, see two Richard Carrigan papers: “IRAS-based Whole-Sky Upper Limit on Dyson Spheres,” Journal of Astrophysics 698 (2009), pp. 2075-2086 (preprint), and “Starry Messages: Searching for Signatures of Interstellar Archaeology,” JBIS 63 (2010), p. 90 (preprint). Also see James Annis, “Placing a limit on star-fed Kardashev type III civilisations,” JBIS 52, pp.33-36 (1999).

A recent Centauri Dreams story on all this is Interstellar Archaeology on the Galactic Scale but see also Searching for Dyson Spheres and Toward an Interstellar Archaeology.

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