# Placing A Limit on Star-Fed Kardashev Type III Civilisations

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### J. Annis (1999), JBIS, 52, 33-36

Refcode: 1999.52.33

Abstract:
A civilisation that uses the bulk of a galaxy’s starlight for its own power requirements is a remarkably obvious entity. This is because galaxies naturally obey scaling laws between the surface brightness, the radius of the stellar distribution and the thermal velocities of the stars. The latter two quantities reflect the mass and its resulting gravitational potential, while the former is the result of this same mass emitting light as stars. If civilisation takes that light for its own purposes, the scaling laws are broken and the galaxy becomes an outlier on plots showing the scaling laws. For a sample of 137 galaxies, no such outliers are found.