This table summarizes interstellar archaeology (IA) in a semi-quantitative manner. The table ranks various possibilities in terms of the Kardashev scale. Lc is an estimate of a typical signal lifetime while the power and mass involved are given as proxies for the "degree of difficulty." Parenthetically, these estimates make an order of magnitude look like precision engineering. See "Starry Messages: Searching for Signatures of Interstellar Archaeology", Richard A. Carrigan, Jr., Journal of the British Interplanetary Society, 63, 90 -103(2010)" or electronically astro-ph arXiv1001.5455 p. 22)
|| The Kardashev scale roughly corresponds to the
magnitude of the challenge or "degree
of difficulty" faced by the
corresponding civilization. Cultural SETI, looking for
unintentional radio signals, remains the best IA
possibility (shown in green). Planetary atmospheres
are more challenging (shown in yellow). Non-natural
atmospheric changes so far introduced in Earth’s
atmosphere are a thousand times too small to be
detected. Breaking up a planet to build a Dyson
sphere completely transcends the long term
dedication of contemporary civilization. There is not even
a mildly plausible technique for stellar engineering.
Surprisingly the step from a Dyson sphere to a Fermi bubble filled
with Dyson spheres only involves a strengthened capability
for space travel.
One measure of the likelihood of finding a signature of IA is the lifetime of the signature. Rough estimates for these lifetimes are given in the Table.
Annis has raised the possibility that his approach to looking for Type III civilizations could be applied to study other astronomical distributions to look for non-natural outliers. Indeed, this embodies some of the spirit of recent discussions about blue stragglers by Livio and Beech.