Type III Societies (Apparently) Do Not Exist
  [Abridged] 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.
