Kardashev Scale

Kardashev scale projections ranging from 1900 to 2100.

The Kardashev scale is a general method of classifying how technologically advanced a civilization is, first proposed in 1964 by the Russian astronomer Nikolai Kardashev. It has three categories, based on the amount of usable energy a civilization has at its disposal and increasing logarithmically:

• Type I — A civilization that is able to harness all of the power available on a single planet, approximately 10¹⁶ W. The actual figure is quite variable; Earth specifically has an available power of 1.74×10¹⁷ W. Kardashev's original definition was 4×10¹² W. (Kardashev had originally defined Type I as a "Technological level close to the level presently attained on earth", "presently" meaning 1964.)
• Type II — A civilization that is able to harness all of the power available from a single star, approximately 10²⁶ W. Again, this figure is variable; the Sun outputs approximately 3.86×10²⁶ W. Kardashev's original definition was 4×10²⁶ W.
• Type III — A civilization that is able to harness all of the power available from a single galaxy, approximately 10³⁶ W. This figure is extremely variable, since galaxies vary widely in size. Kardashev's original definition was 4×10³⁷ W.

All such civilizations are purely hypothetical at this point. However, the Kardashev scale is of use to SETI researchers, science fiction authors, and futurists as a theoretical framework.

There is also a hypothetical "type IV", which includes such fictional species such as the time-traveling Time Lords in the television series, "Doctor Who". The exact definition of a type IV species is uncertain, however often said to be species that can utilise all the power available from ten billion galaxies (10⁴⁶ W). Further numbers in the Kardashev scale could be extrapolated, but there is not much use for it because larger amounts of energy approach the limits for the universe.