Editing Kardashev scale (section)

=== Sagan's finer classification ===
In 1973, [[Carl Sagan]] discovered Kardashev's work on the classification of civilizations.<ref name="Galantai-2006">{{Cite journal |last=Galantai |first=Zoltan |date=2006 |title=After Kardashev: Farewell to Super Civilizations |url=https://www.academia.edu/1018345 |journal=Contact in Contex |volume=2 |issue=2 |archive-date=2024-08-18 |access-date=2023-08-08 |archive-url=https://web.archive.org/web/20240818005401/https://www.academia.edu/1018345 |url-status=live }}</ref> He found that the differences between the types Kardashev identified were so great that they did not allow for the best possible modeling of the evolution of civilizations.<ref name="Galántai-2003" /> Consequently, Sagan proposes a more refined classification, still based on Kardashev's types, but integrating intermediate levels using the following [[Logarithmic scale|logarithmic]] [[interpolation]] formula:<ref name="Carrigan Jr.-20102">{{Cite journal |last=Carrigan Jr. |first=Richard A. |date=2010 |title=Starry Messages: Searching for Signatures of Interstellar Archaeology |journal=Journal of British Interplanetary Society |volume=63 |issue=90 |pages=121–126 |arxiv=1001.5455 |bibcode=2010JBIS...63...90C}}</ref>

<math>K = \frac{\log_{10}{W}-6} {10}</math>,

where ''K'' is the Kardashev type of a civilization and ''W'' is the amount of power it uses, in watts. Thus, a ''Type 1.1'' civilization would be defined by a power of 10<sup>17</sup> watts, while a ''Type 2.3'' civilization would be able to harness 10<sup>29</sup> watts.

Moreover, the above formula could be used to extrapolate beyond Kardashev's original types. For example, a '''''Type&nbsp;0''''' civilization, not defined by Kardashev, would control about 1&nbsp;MW of power (equivalent to having around 100 campfires burning at any given time); on Earth, the emergence of Type 0 civilizations is roughly concurrent with the [[Cradle of civilization#Rise of civilization|rise of civilization]] in a general sense.<ref>{{Cite thesis |title=Environmental Change and Human Impact during the Mesolithic-Neolithic Transition in North-West Europe|url=https://research.manchester.ac.uk/files/84029587/FULL_TEXT.PDF |degree=PhD |publisher=[[University of Manchester]] |first=Sarah Elizabeth |last=Kneen |date=2014}}</ref>

Sagan estimated that, according to this revised scale, 1970s humanity would be Type 0.7 (about 10 [[terawatts]]),<ref name="Sagan-19732">{{Cite journal |last=Sagan |first=Carl |date=1973-07-01 |title=On the detectivity of advanced galactic civilizations |url=https://dx.doi.org/10.1016/0019-1035%2873%2990112-7 |journal=Icarus |language=en |volume=19 |issue=3 |pages=350–352 |bibcode=1973Icar...19..350S |doi=10.1016/0019-1035(73)90112-7 |issn=0019-1035}}</ref> equivalent to 0.16% of the power available on Earth.<ref name="Wilson-20112">{{Cite book |last=Wilson |first=Richard |title=International Seminar on Nuclear War and Planetary Emergencies – 43rd Session |publisher=World Scientific Publishing Company |year=2011 |isbn=978-9814365925 |edition=1st |pages=51–61 |chapter=Energy and the Environment in the Next Millenium |doi=10.1142/8232}}</ref> This level is characterized, according to him, by the ability to self-destruct, which he calls "technological adolescence".<ref name="Lemarchand-20002"/> In 2021, the total [[World energy supply and consumption|world energy consumption]] was 595.15 [[Joule#Exajoule|exajoules]] (165,319&nbsp;[[Kilowatt-hour#Watt-hour multiples|TWh]]),<ref>{{Cite web |title=The Statistical Review of World Energy 2022 |url=https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2022-full-report.pdf |url-status=live |archive-url=https://web.archive.org/web/20230821195021/https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2022-full-report.pdf |archive-date=2023-08-21 |access-date=2023-08-24 |website=bp}}</ref> equivalent to an average power consumption of 18.87 TW or a Kardashev rating of 0.73&nbsp;(to 2 [[Significant figures|s.f.]]).<ref>{{Citation |last1=LePoire |first1=David J. |title=Energy Flow Trends in Big History |date=2020 |url=https://doi.org/10.1007/978-3-030-33730-8_9 |work=The 21st Century Singularity and Global Futures: A Big History Perspective |pages=185–200 |editor-last=Korotayev |editor-first=Andrey V. |access-date=2023-09-09 |series=World-Systems Evolution and Global Futures |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-030-33730-8_9 |isbn=978-3-030-33730-8 |s2cid=213212248 |last2=Chandrankunnel |first2=Mathew |editor2-last=LePoire |editor2-first=David J.}}</ref>

Sagan also suggests that, for completeness, an alphabetical scale should be added to indicate the level of [[Social change|social development]], expressed in the amount of information available to the civilization. Thus, a Class A civilization would be based on 10<sup>6</sup> [[bit]]s of information (less than any recorded human culture), a Class B on 10<sup>7</sup>, a Class C on 10<sup>8</sup>, and so on. Humanity in 1973 would belong to the "0.7 H" class.<ref name="books.google.com">{{cite book |last=Sagan |first=Carl |url=https://books.google.com/books?id=lL57o9YB0mAC&pg=PA156 |title=Cosmic Connection: An Extraterrestrial Perspective |year= 2000 |publisher=[[Cambridge University Press]] |others=[[Freeman Dyson]], David Morrison |isbn=978-0-521-78303-3 |editor-last=Agel |editor-first=Jerome |edition= |series= |location= |pages= |language= |chapter= |doi= |oclc= |id= |quote=I would suggest Type 1.0 as a civilization using 10<sup>16</sup> watts for interstellar communication; Type 1.1, 10<sup>17</sup> watts; Type 1.2, 10<sup>18</sup> watts, and so on. Our present civilization would be classed as something like Type 0.7. |author-link=Carl Sagan |access-date=2008-01-01 |orig-date=1973 |via=[[Google Books]]}}</ref> According to Sagan, the first civilization with which humanity would come into contact could be between "1.5 J" and "1.8 K"; a galactic supercivilization would be at the "3 Q" stage, while a federation of galaxies could be at the "4 Z" stage.<ref name="Lemarchand-20002"/> The information and energy axes are not strictly interdependent, so even a level Z civilization would not have to be Kardashev Type&nbsp;III.<ref name="books.google.com" /> Sagan believed that no civilization had yet reached level Z, speculating that so much unique information would exceed that of all the intelligent species in a [[galactic supercluster]], and observing that the universe is not old enough to exchange information effectively over large distances.

In 2017, the total amount of information generated on the [[internet]] was [[Zettabyte Era|26 zettabytes]] (with an estimated 120 zettabytes in 2023),<ref>{{Cite web |title=Data growth worldwide 2010-2025 |url=https://www.statista.com/statistics/871513/worldwide-data-created/ |access-date=2023-11-19 |website=Statista |language=en |archive-date=2024-08-30 |archive-url=https://web.archive.org/web/20240830140921/https://www.statista.com/statistics/871513/worldwide-data-created/ |url-status=live }}</ref> equivalent to 0.73 R/S on Sagan's combined scale.