Editing Kardashev scale (section)

==== Towards an energetic definition of civilization ====
In 1980, Nikolai Kardashev published a second article entitled ''Strategies of Searching for Extraterrestrial Intelligence: A Fundamental Approach to the Basic Problem,''<ref name="Kardashev-1980">{{Cite journal |last=Kardashev |first=Nikolai S. |date=1980 |title=Strategies of Searching for Extraterrestrial Intelligence: A Fundamental Approach to the Basic Problem |url=http://www.bigear.org/CSMO/HTML/CS07/cs07p36.htm |url-status=live |journal=Cosmic Search |volume=2 |issue=7 |pages=36–38 |bibcode=1980CosSe...2...36K |archive-url=https://web.archive.org/web/20230727035448/http://www.bigear.org/CSMO/HTML/CS07/cs07p36.htm |archive-date=2023-07-27}}</ref> in which he stated that:{{Blockquote|text=Detection and studies of extraterrestrial civilizations constitute a problem of immense significance for the progress of humanity and for its culture and philosophy. The discovery of intelligent life in the Universe would provide a guideline to the possible development of our civilization over astronomical time spans.|author=Nikolai Kardashev|title=Strategies of Searching for Extraterrestrial Intelligence: A Fundamental Approach to the Basic Problem}}

[[File:Annual_world_primary_energy_consumption.svg|alt=A broken line in blue goes, from left to right, from the bottom to the top|thumb|upright=2|A graph of world [[World energy supply and consumption|primary energy consumption]] in 2011 according to the BP ''Statistical Review'']]
According to the Soviet astronomer, the Earth's civilization would be too young to be able to contact another civilization that would certainly be more advanced; the [[Solar System]] is too young with its five billion years, and the first ancestors of today's man appeared only 6 million years ago at the earliest;<ref>{{Cite journal |last=Begun |first=David R. |date=2010-10-21 |title=Miocene Hominids and the Origins of the African Apes and Humans |url=https://www.annualreviews.org/doi/10.1146/annurev.anthro.012809.105047 |journal=Annual Review of Anthropology |language=en |volume=39 |issue=1 |pages=67–84 |doi=10.1146/annurev.anthro.012809.105047 |issn=0084-6570 |doi-access=}}</ref> the oldest celestial objects are between 10 and 14 billion years old; it is clear that the other civilizations are incomparably older than the human civilization. Therefore, the knowledge of these civilizations must be greater than Earth's, and, he reasoned, they must surely be aware of what humans are doing.<ref name="Kardashev-1980" />

Kardashev believed it is probable that the present state of Earth's civilization is only one of the stages through which civilizations pass during their evolution. It is thus possible to define [[civilization]] on the basis of this universal characteristic, which allowed [[Aleksandr Lyapunov]] to define life as "a highly stable state of matter, which uses information encoded by the states of individual molecules to produce maintaining reactions", which Kardashev calls the "functional definition of civilization".<ref name="Kardashev-1980" /> He therefore suggests thinking of civilization as a "highly stable state of matter capable of acquiring, making abstract analysis of, and utilizing information to obtain qualitatively new information about its environment and about itself, to improve its capabilities of gathering new information for producing sustaining reactions."<ref name="Kardashev-1980" />

Civilization is therefore characterized by the quality of the [[information]] acquired by its operating program, and by the [[energy]] required to implement these functions. By "information about its environment and about itself", Kardashev specified that it is data about organic or inorganic nature, [[science]], [[technology]], [[economy]], [[culture]], [[The arts|arts]], etc. From this definition, he proposed a diagram representing the interactions between a civilization and its environment, and enumerated a number of scientific problems arising from these interactions with the information available in the Universe.<ref name="Kardashev-1980" />

From this definition, Kardashev drew three conclusions. The first postulated that because of the vast and unlimited set of activities required by scientific problems, the period during which civilizations must transmit and communicate is necessarily long, even unlimited. On the other hand, since our present development covers only a negligible fraction of this [[Interstellar communication|communication phase]], Kardashev hypothesized the high improbability that we will meet "brothers in intelligence" who are at the same stage of evolution as are we. After all, highly advanced civilizations know and use the [[Scientific law|laws of physics]] to a degree that we have yet to suspect. Kardashev asserted that "this last point should be taken into account in the research programs of extraterrestrial civilizations" and concluded that it is very likely that our present state is only one of the stages through which every civilization passes during its evolution.<ref name="Kardashev-1980" />