Measuring Civilizations in the Cosmos

Our universe is a huge place, home to about 2 trillion galaxies each possibly being home to alien species much like our own milky way galaxy. In our search for extraterritorial life, the question arises, what are we looking for?

The Kardashev scale is a method of measuring a civilization's level of technological advancement based on the amount of energy it is able to use. The measure was proposed by Soviet astronomer Nikolai Kardashev in 1964.

The scale is hypothetical, and regards energy consumption on a cosmic scale. 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.

Kardashev first outlined his scale in a paper presented at the 1964 Byurakan conference, a scientific meeting that reviewed the Soviet radio astronomy space listening program. Kardashev proposed a classification of civilizations into three types, based on the postulate of exponential progression. A type I civilization is able to access all the energy available on its planet and store it for consumption. A type II civilization can directly consume the energy of a star. Finally, a type III civilization is able to capture all the energy emitted by its galaxy. In a second article, entitled Strategies of Searching for Extraterrestrial Intelligence and published in 1980, Kardashev wonders about civilization, which he defines by its capacity to access energy, to maintain itself and to integrate information from its environment. Two other articles followed: On the Inevitability and the Possible Structure of Supercivilizations and Cosmology and Civilizations, published respectively in 1985 and 1997; the Soviet astronomer proposes tracks to detect supercivilizations and to direct the SETI programs.

Propper definitions of civilization types are as follows.

Type I

A civilization close to the level presently attained on Earth, A Type I civilization is usually defined as one that can harness all the energy that reaches its home planet from its parent star, which is about four orders of magnitude higher than the amount presently attained on Earth. The astronomer Guillermo A. Lemarchand defined Type I as a level near contemporary terrestrial civilization with an energy capability equivalent to the solar insolation on Earth.

Type II

A civilization capable of harnessing the energy radiated by its own large star—for example, by means of the successful completion of a Dyson sphere or Matrioshka brain. Lemarchand defined civilizations of this type as being capable of using and channeling the entire radiation output of its star. The energy use would then be comparable to the luminosity of the Sun.

Type III

A civilization in possession of energy at the scale of its own galaxy. Lemarchand defined civilizations of this type as having access to power comparable to the luminosity of the entire Milky Way galaxy. Kardashev believed that a Type 4 civilization was impossible, so he did not go past Type 3. However, new types (0, 4, 5, and 6) have been proposed.

At the current time, humanity has not yet reached Type I civilization status. Physicist and futurist Michio Kaku suggested that, if humans increase their energy consumption at an average rate of 3 percent each year, they may attain Type I status in 100–200 years, Type II status in a few thousand years, and Type III status in 100,000 to a million years. Carl Sagan suggested defining intermediate values (not considered in Kardashev's original scale).

The framework for the search for and detection of advanced civilizations was constructed and theorized during the conference held in 1964 in Armenia, at the Byurakan astrophysical observatory. Starting from a functional definition of civilization, based on the immutability of physical laws and using the human civilization as a model of extrapolation, the initial model of Kardashev was developed. Several scientists have conducted various searches for possible civilizations, but without conclusive results. Based on these criteria, unusual objects, now known to be either pulsars or quasars, were identified. Kardashev has described in his various publications a set of listening and observing parameters to be taken into account.