Type III Kardashev Civilizations do NOT Exist in the Observable Universe

Type III Societies (Apparently) Do Not Exist

Authors:

Lacki et al

Abstract:

Whether technological societies remain small and planet-bound like our own, or ultimately span across galaxies is an open question in the Search for Extraterrestrial Intelligence. Societies that engineer on a galactic scale are classified as Type III on Kardashev's scale. I argue that Type III societies can take the form of blackboxes, entire galaxies veiled in an opaque screen. A blackbox has a temperature that is just above that of the cosmic microwave background. The screen can be made from artificial dust pervading the galaxy. I show that there is enough material in galaxies to build blackboxes if the dust is fashioned into dipole antennas. The thermal emission of a blackbox makes it a bright microwave source. I examine the Planck Catalog of Compact Sources to constrain the abundance of blackboxes. None of the 100 GHz sources has the spectrum expected of a blackbox. The null result rules out shrouded galaxy clusters out to z ~ 1 and shrouded Milky Ways out to (comoving) 700 Mpc. The reach of the results includes 3 million galaxies containing an estimated 300 quadrillion terrestrial planets, as well as tens of thousands of galaxy clusters. Combined with the null results from other searches for Type III societies, I conclude that they are so rare that they basically do not exist within the observable Universe. A hypothesis of "Cosmic Pessimism" is discussed, in which we are alone, our long-term chances for survival are slim, and if we do survive, our future history will be checkered. Our loneliness is suggested by the lack of Type III societies. I discuss the remaining forms of Type III societies not yet well constrained by observation. I argue that the ease of building blackboxes on planetary and Solar System scales may lead, within a few centuries, to environmental catastrophes vastly more devastating than anything we are doing now, boding ill for us.

Improving on the Kardashev Scale

Kardashev's Classification at 50+: A Fine Vehicle with Room for Improvement

Authors:

Cirkovic et al

Abstract:

We review the history and status of the famous classification of extraterrestrial civilizations given by the great Russian astrophysicist Nikolai Semenovich Kardashev, roughly half a century after it has been proposed. While Kardashev's classification (or Kardashev's scale) has often been seen as oversimplified, and multiple improvements, refinements, and alternatives to it have been suggested, it is still one of the major tools for serious theoretical investigation of SETI issues. During these 50+ years, several attempts at modifying or reforming the classification have been made; we review some of them here, together with presenting some of the scenarios which present difficulties to the standard version. Recent results in both theoretical and observational SETI studies, especially the G-hat infrared survey (2014-2015), have persuasively shown that the emphasis on detectability inherent in Kardashev's classification obtains new significance and freshness. Several new movements and conceptual frameworks, such as the Dysonian SETI, tally extremely well with these developments. So, the apparent simplicity of the classification is highly deceptive: Kardashev's work offers a wealth of still insufficiently studied methodological and epistemological ramifications and it remains, in both letter and spirit, perhaps the worthiest legacy of the SETI "founding fathers".