Nikolai Kardashev

Nikolai Semenovich Kardashev (1932 - 2019) was a Russian astrophysicist, Doctor of Physical and Mathematical Sciences, and deputy director of the Astro Space Center (Russia) of PN Lebedev Physical Institute of the Russian Academy of Sciences in Moscow.

In 1963 Kardashev examined quasar CTA-102, the first Soviet effort in the search for extraterrestrial intelligence (SETI). In this work he came up with the idea that some galactic civilizations would be perhaps millions or billions of years ahead of us, and created the Kardashev Scale to rank such civilizations. Kardashev defined three levels of civilizations, based on energy consumption:
 * Type I with "technological level close to the level presently attained on earth, with energy consumption at ≈4×1019 erg/sec (4 × 1012 watts)"
 * Type II, "a civilization capable of harnessing the energy radiated by its own star"
 * Type III, "a civilization in possession of energy on the scale of its own galaxy".

Various extensions of the scale have since been proposed, including a wider range of power levels, and the use of metrics other than pure power.