Once again thanks are due to Paul Carr for inviting me to participate in another episode of The Unseen Podcast. This time we talked about a subject that is close to my heart: Kardashev’s typology of civilizations, which I previously wrote about in What Kardashev Really Said on Centauri Dreams.
The pretext for a discussion of Kardashev supercivilizations is the recent publication of a scientific paper that has attempted to search for galaxy-spanning supercivilizations (Kardashev Type III) by looking for the infrared signatures that would presumably accompany such a large-scale use of energy -- one might even say an astronomical use of energy.
While it is the most recent paper that has gotten a lot of attention, because it gives the results of the study, the recent paper is the third of three papers, and to fully understand and appreciate the results presented in the third paper, you really need to read the theoretical framework provided in the first paper and the details of how the study was approached in the second paper.
Here are links to all three papers:
The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. I. Background and Justification by J. T. Wright, B. Mullan, S. Sigurðsson, and M. S. Povich
The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. II. Framework, Strategy, and First Result by J. T. Wright, R. Griffith, S. Sigurðsson, M. S. Povich, and B. Mullan
The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. III. The Reddest Extended Sources in WISE by Roger L. Griffith, Jason T. Wright, Jessica Maldonado, Matthew S. Povich, Steinn Sigurdsson, and Brendan Mullan
Paul Gilster has posted a good summary of some of this research in G-HAT: Searching For Kardashev Type III.
The search for infrared signs of high energy usage could be the search for trace heat from a Dyson sphere, something that Dyson suggested several decades ago, and Kardashev also urged as a SETI strategy, but it could also simply be the waste heat inevitably generated by energy usage on the scale of galactic megaengineering, or astroengineering, if you prefer. As I noted in the podcast, the idea of finding a Dyson sphere is very exotic, but it tends to distract from the overall SETI task of formulating and then searching for the thermodynamic profiles of extraterrestrial civilizations, and this in turn is part of the larger effort to arrive at detection signatures for ETI and alien life.
