Kardashev scale

thumb|upright=1.2|alt=Three schematic representations: Earth, Solar System and Milky Way|Energy consumption in three types of civilization as defined by Sagan's extended Kardashev scale

The Kardashev scale () is a method of measuring a civilization's level of technological advancement based on the amount of energy it is capable of harnessing and using. The measure was proposed by Soviet astronomer Nikolai Kardashev in 1964, Starting from a functional definition of civilization, based on the immutability of physical laws and using human civilization as a model for extrapolation, Kardashev's initial model was developed. He proposed a classification of civilizations into three types, based on the axiom of exponential growth:

• A Type I civilization (planetary) is able to access all the energy available on its planet and store it for consumption.
• A Type II civilization (stellar) can directly consume a star's energy, most likely through the use of a Dyson sphere.
• A Type III civilization (galactic) is able to capture all the energy emitted by its galaxy, and every object within it, such as every star, black hole, etc.

Under this scale, the sum of human civilization does not reach Type I status, though it continues to approach it. Extensions of the scale have since been proposed, including a wider range of power levels (Types 0, IV, and V) and the use of metrics other than pure power, e.g., computational growth or food consumption. However, in part thanks to such searches, unusual objects, now known to be either pulsars or quasars, were identified.

Origin of the classification

First publication (1964)

alt=A red dotted line that goes up from left to right.|thumb|upright=1.4|A projection of the Kardashev scale to 2040 based on data from the International Energy Agency World Energy Outlook

Kardashev presented for the first time a classification of civilizations according to the level of the rate of their energy consumption, or ability to harness power, in an article entitled Transmission of Information by Extraterrestrial Civilizations, published in 1964 first in Russian in the March–April issue of the Astronomicheskii Zhurnal,

A civilization known as "Type I" has achieved a technological level close to the one attained on Earth at the time Kardashev's article was submitted (December 1963), with a rate of energy consumption evaluated at about 4 × 10¹² watts (W). A civilization known as "Type II" would surpass the first by fourteen orders of magnitude, matching the entire power emitted by the Sun in about 3,200 years, i.e, Earth's home star's "output" at that time, predicted at 4 × 10²⁶ W. Finally, a civilization known as "Type III" reaches the milepost set in 5,800 years when humanity's rate of energy consumption is predicted by the author to match the power emitted by the approximated 10¹¹ stars in the Milky Way galaxy, which involves harnessing power of up to an estimated 4 × 10³⁷ W.

Kardashev then examined the characteristics of a transmission from an artificial source. He mentioned the two cosmic radio sources discovered in 1963 by the California Institute of Technology, CTA-21 and CTA-102 in particular, which would have characteristics close to those of a presumed artificial source. The most suitable region of the galaxy for observing Type II and III civilizations would then be the Galactic Center, due to the high density of the stellar population it harbors. He then recommended that the search programs for such artificial sources should focus on other nearby galaxies, such as the Andromeda Galaxy, the Magellanic Clouds, M87, \or Centaurus A. Kardashev concluded his paper by noting that the possible discovery of even the simplest organisms on Mars would increase the likelihood that Type II civilizations exist in the galaxy. in which he stated that:

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; 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. For this supercivilization, the science of "cosmic ethnography" must be highly developed. However, the fact that no contact has been made so far could be explained by ethical considerations of these civilizations. Based on this principle, Kardashev sees only two possible evolutionary scenarios for a supercivilization: natural evolution and evolution after contact with other extraterrestrial civilizations. He considers more likely the scenario based on contact between two highly developed, technologically and culturally advanced civilizations; this scenario, which he calls the "Urbanization Hypothesis", would result in the regrouping and unification of several civilizations within a few compact regions of the Universe. and omnidirectional emission up to 21 cm. In the event of contact, humanity would see progress in all areas of society in order to join this supercivilization; it is also expected that an ethnographic conservatory would be created on Earth.

1. The scenario of a unification on the scale of the galactic cluster has only a 20% probability of realization. Kardashev advises to observe the Virgo cluster (especially M87) and other clusters in a similar way as in the first scenario. The consequences for humanity are the same as in the first scenario.
2. The scenario of a unification on the scale of galaxies has only a 10% probability. To confirm it, we must study the galactic centers, both of the Milky Way and of neighboring galaxies (such as M31, M33), according to a procedure similar to that of the first scenario. The consequences for humanity are the same as in the first scenario.
3. The scenario of a complete colonization of space has no probability of being realized according to Kardashev because if it were realizable then "they" would already be on Earth; yet this is not the case. However, in the case of a contact, the consequences on humanity are the same as in the first scenario.
4. This scenario assumes that all civilizations would have destroyed themselves before any contact. Kardashev estimates the probability of this to be 10%. Humanity should be able to detect ancient megastructures in the vicinity of the nearest stars. As a result, no contact with humanity can take place.
5. The last scenario suggests that we are the first or the only ones in the Universe. Kardashev estimates its probability at 10%. Only exobiology can confirm or falsify such a scenario. We can imagine a potential contact in the distant future, and then the consequences would be similar to those of the other five scenarios.

Fourth publication (1997)

alt=Color illustration. An object resembling a truncated trumpet has white spots on its surface.|thumb|upright=2|According to the [[Standard Model|standard model describing the expansion of the Universe since the Big Bang, there may be planets older than the Earth, capable of harboring supercivilizations.]]

In the article Cosmology and Civilizations published in 1997, Kardashev reiterates the need to carefully observe astronomical objects with strong radiation in order to detect supercivilizations. However, the discovery of a civilization at a stage of development similar to ours is unlikely. The existence of such supercivilizations is made possible by the fact that life on Earth is recent compared to the age of the Universe (8 × 10⁹ years before the formation of the Solar System). He then examines the conditions for the appearance of life on cosmological time scales. Assuming the rate of evolution of life on Earth and considering the age of the Universe, it is reasonable to assume that a civilization could have reached our level of technological development in 6 × 10⁹ years. Such civilizations can be observed in nearby regions, since the farther away we observe, the younger the objects are. Recent discoveries of sources of intense radiation deadly to life show that life could have flourished under cover for the time necessary for its appearance and maintenance. Another argument for the possibility of a very old supercivilization is that most of the objects that could be megastructures have not yet been discovered and mapped. In addition, 95% of the matter remains invisible or can only be inferred by the gravitational influence it produces.

According to Kardashev, it is essential to focus our search tools on new objects radiating at a wavelength of a few microns to a few millimeters, and at a temperature of 3 to 300 K, which is characteristic of large structures of solid matter. It would then be possible to detect structures belonging to Type II in our galaxy or in those nearby. Type III structures can also be observed at large cosmological distances. Kardashev recalls that a study was conducted on 3000 sources of the IRAS catalog from the four directions of the sky. Two temperature bands were targeted: from 110 to 120 K and from 280 to 290 K. The analysis showed that the 110–120 K sources are clustered in the Galactic plane and in its center. Kardashev explains that only more powerful observations in the infrared and submillimeter range can reveal possible artificial sources of radiation. He then refers to projects that he has proposed, in particular that of putting into orbit a cryogenic space telescope (the Millimetron Project).

According to Kardashev, these results, combined with those of other research on the age of certain cosmic objects, suggest that civilizations dating from 6 to 8 billion years ago may exist in our galaxy. It is likely that they have long since discovered our own civilization, a hypothesis that could answer the question posed by Enrico Fermi when he formulated his paradox: "Where are they?". Without the discovery of artificial sources, however, Shklovsky's theory that civilizations self-destruct as a result of large-scale social conflicts would be proven. Kardashev mentions another hypothesis that, in his opinion, is capable of explaining the dynamics of the supercivilizations: the "feedback effect" (theorized by Sebastian von Hoerner in 1975), which is based on the hypothesis that at a high technological level, civilizations tend to converge rather than to isolate themselves. The distance between supercivilizations could then be determined by half the time of the technological evolution of the oldest civilization, which would be about 3 to 4 billion years. On the other hand, this supercivilization may not have been present in our galaxy for a long time. Kardashev concludes by saying that since the expansion of the Universe is infinite, the number and lifetime of such supercivilizations are also infinite. The purpose of this classification is to guide the search for extraterrestrial civilizations, particularly within SETI, in which Kardashev participated, and this on the assumption that a fraction of the energy used by each type is intended for communication with other civilizations. To make this scale more understandable, Lemarchand compares the speed at which a volume of information equivalent to 100,000 average-sized books can be transmitted across the galaxy. A Type II civilization can send this data using a transmission beam that lasts for only 100 seconds. A similar amount of information can be sent across intergalactic distances of about ten million light years, with a transmission time of several weeks. A Type III civilization can send the same amount of data to the entire observable universe with a transmission time of 3 seconds.

Kardashev's classification is based on the assumption of a growth rate of 1% per year. Kardashev believed that it would take humanity 3,200 years to reach Type II, and 5,800 years to reach Type III. However, Dr. Michio Kaku believes that humanity must increase its energy consumption by 3% per year to reach Type I in 100–200 years. These types are thus separated from each other by a growth rate of several billion.

Type II

A civilization capable of harnessing the energy radiated by its own large star – for example, by successfully completing a Dyson sphere or Matrioshka brain – with an energy consumption of ≈4 erg/sec. 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.

<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 10¹⁷ watts, while a Type 2.3 civilization would be able to harness 10²⁹ 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 rise of civilization in a general sense.

Sagan estimated that, according to this revised scale, 1970s humanity would be Type 0.7 (about 10 terawatts), equivalent to 0.16% of the power available on Earth. This level is characterized, according to him, by the ability to self-destruct, which he calls "technological adolescence". equivalent to an average power consumption of 18.87 TW or a Kardashev rating of 0.73.

Sagan also suggests that, for completeness, an alphabetical scale should be added to indicate the level of social development, expressed in the amount of information available to the civilization. Thus, a Class A civilization would be based on 10⁶ bits of information (less than any recorded human culture), a Class B on 10⁷, a Class C on 10⁸, and so on. Humanity in 1973 would belong to the "0.7 H" class. 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. equivalent to 0.73 R/S on Sagan's combined scale.

Kaku and the knowledge economy

In Physics of the Future (2011), American physicist Michio Kaku examines the conditions for humanity to converge on a Type&nbsp;I planetary civilization. This convergence is based primarily on the knowledge economy. Kaku uses the Kardashev scale, but develops it by adding an additional stage: a Type&nbsp;IV civilization would be able to draw the energy it needs from extragalactic radiation. By studying the evolution of technologies that have changed history (paper, the integrated circuit), Kaku believes that humanity is moving toward a civilization of planetary dimensions, the "starting point" of which is the Internet.

A Type&nbsp;I civilization consumes power on the order of thousands to millions of times our current planetary output, about 100 trillion trillion watts. It would have enough energy to manipulate the occurrence of certain natural phenomena, such as earthquakes or volcanoes, and could build cities on the oceans. We can see the beginnings of a Type&nbsp;I civilization in the fact that a global language is developing (English), a global communication system is emerging (the Internet), a global economic system is in the making (the establishment of the European Union), and even a globalized culture is standardizing humanity (mass media, television, rock music, and Hollywood movies).

Zubrin's planet mastery

In Entering Space: Creating a Spacefaring Civilization, Robert Zubrin suggests another form: his definition of a Type&nbsp;I civilization is described as one that has achieved full mastery of the resources of its planet (global), a Type&nbsp;II of its solar system (interplanetary), and a Type&nbsp;III would have unleashed the full potential of the galaxy (starfaring civilization). Metrics other than pure energy consumption have also been proposed.

He ponders the possibility of a Type&nbsp;IV civilization, one that would dominate the universe, noting that there are limits to how minds can connect and interact on a galactic or intergalactic basis. As an example, he mentions that communication from the Galactic Center of the Milky Way galaxy to its edge would take about 50,000 years (since nothing can travel faster than light, according to our understanding of physics).

In Impossibility: The Limits of Science and the Science of Limits (1998), Barrow proposes a scale ranging from "BI" to "BVI", with an ultimate stage he calls "BΩ", the former characterized by the possibility of manipulating one's environment, while the latter allows for the modification of spacetime.

Galántai's miniaturization and resilience to catastrophes

alt=Color illustration. A burning object pierces the surface of a much larger object.|thumb|For Zoltan Galántai, a scale classifying civilizations should be based on their ability to survive catastrophes, particularly those of cosmic origin, such as an [[Impact event|asteroid impact.]]

Zoltan Galántai recognizes the important role that Kardashev's classification has played in the SETI program, but he believes that another scale is possible, without using energy consumption, by resorting to miniaturization. The hypothesis of Donald Tarter, researcher at SETI, is that a civilization based on nanotechnology would not need an ever-increasing amount of energy. A Type&nbsp;I civilization that masters local space travel could colonize its planetary system and even the Oort cloud without needing an amount of energy that would make it Type&nbsp;II.

Physicist Freeman Dyson has calculated that Type&nbsp;I should be reached in about 200 years, while Richard Carrigan has estimated that the Earth is just four-tenths of the way to Type&nbsp;I on the Sagan scale. If Type&nbsp;I is reached soon (in the year 3000 for Richard Wilson), it would be accompanied by profound social upheavals, but also by a significant risk of self-destruction. Nuclear energy cannot fully meet the world's energy needs (it represented only 6% in 2011). In addition, renewable energy cannot meet the growing demand for energy. Most of the minerals used by humans are in danger of becoming scarce; 11 minerals are already classified as having passed their peak production. For Metzger, humanity must therefore undertake a "100-year project" aimed at building a spacecraft ("100 Year Starship") capable of accessing the vast energy resources of the Solar System. allowing it, among other things, to capture its energy and navigate the galaxy.

Towards type III

alt=Color illustration. A yellow-orange disc in the center is pierced vertically by a spiral of filaments.|thumb|Artist's view of [[quasar GB1508. According to Russian astronomer Kardashev, a highly evolved civilization, known as "Type&nbsp;III" in his theoretical classification, would be able to draw its energy from such a source.]]

A Type&nbsp;III civilization should be detectable because of the large amount of radiation captured on a galaxy-wide scale. Calissendorff suggests using 75% of the total light emitted by a galaxy to determine that a Type&nbsp;III civilization uses many Dyson spheres. If only three or four of these spheres occupy the galaxy, it does not necessarily mean that the civilization has reached Type&nbsp;III, and it may still be in transition;

Towards type IV

Zoltan Galántai notes that neither Kardashev nor Sagan thought to extend the scale and define a Type&nbsp;IV (which would use the energy of an entire universe). They simply did not envision a civilization capable of manipulating its environment on the largest possible scale (about 14 billion parsecs).

Possible scenarios

According to Kardashev, the most important parameters to define the existence of a civilization are three: the presence of very powerful energy sources, the use of non-standard technologies, and the transmission of significant amounts of information of various kinds through space.

Energy sources

Kardashev's classification is based on the hypothesis that an advanced civilization uses significant energy, which implies that it must be de facto detectable over long distances, as summarized by Zoltan Galántai.

Dutil and Dumas consider several physical limits to continuous energy production, such as photosynthesis (about 10 TW), climate (about 127 TW), and solar flux (174,000 TW). The only inexhaustible source of energy that can sustain a civilization for over several billion years, is deuterium (used in nuclear fusion). as well as the contribution of heavy elements. It could also be a change in the isotopic ratio, due to a stellar engine, or an unusual spectral modulation in the composition of the star. or X-ray emissions) can confirm that it is an intelligent transmission. Two sources among those studied have parameters close to those expected: 1934-63 and 3C 273B. Only Type&nbsp;II or III civilizations can communicate using isotropic transmissions that allow omnidirectional reception. In a 1&nbsp;MHz band (which requires about 10²⁴ watts), detection of signals from a Type&nbsp;II civilization is possible up to 1,000 light-years away, while signals from a Type&nbsp;III civilization are detectable virtually throughout the observable Universe.

For Zoltan Galántai, we would not be able to distinguish between an intelligent extraterrestrial signal and a signal of natural origin. Therefore, he does not believe that Type&nbsp;II, III or even IV civilizations can be detected. Even if humanity reaches Type&nbsp;IV, it will not be able to detect another supercivilization of a similar level, and we will consider their changes in the universe to be the result of natural causes. Thus, there may be many Type&nbsp;IV civilizations in the universe, but none of them will be able to detect the others. Moreover, the dimensions of the universe make these supercivilizations like islands far from the others, which Dyson defines as a "Carroll Universe". In 2007, the SETI program analyzed the only television frequencies sent by a Type&nbsp;0 civilization, notes Michio Kaku. Therefore, our galaxy may have communications from Type&nbsp;II and III civilizations, but our listening devices can only detect Type&nbsp;0 messages. This national conference was held in response to the American seminar known as the Green Bank conference of 1961, which was held at the Green Bank observatory in the United States. It brought together radio astronomers with the aim of "finding rational technical and linguistic solutions to the problem of communication with an extraterrestrial civilization that is more advanced than the Earth's civilization". Kardashev presented his classification, while Troitskii announced that it was possible to detect signals from other galaxies.

For Kardashev, "in the next 5 to 10 years, all the sources of radiation with the largest observable flux, in all the regions of the electromagnetic spectrum, will have been discovered and studied", the sensitivity of the listening devices having indeed reached their technical limits. According to him, the entire electromagnetic spectrum will be known and, consequently, the list of the objects that could be artificial sources could thus be extended. The search for artificial signals will then have to concentrate on objects of maximum luminosity or radiation belonging to a certain region of the spectrum, but also on objects of significant mass, and on those that represent the essence of matter in the Universe. As early as 1971, Kardashev considered that this observation requires the preparation of a plan of listening and analysis, which will allow the success of the search for extraterrestrial civilizations. Humanity will then be able to solve the "main dilemma", as it was stated by Enrico Fermi.

Kardashev believes that a research project like Ozma is incapable of detecting a Type&nbsp;I civilization (an idea also promoted by Kaplan in 1971), and that SETI should instead focus on searching for intense radio signals that could emanate from active Type&nbsp;II or III civilizations.

However, these universal laws are not the only parameters to consider. Zoltan Galántai explains that "it is impossible to calculate the future of the Universe over long periods of time without including the effects of life and intelligence", a position close to that of Freeman Dyson. Therefore, the time to double technical knowledge is about ten years, and to double energy output, available reserves, and population is about 25 years. Two scenarios are then possible: spatial expansion or energy stagnation, the latter being possible only for 125 years, according to Kardashev, using the following relationship <math>\alpha = 1.04</math>:

<math display="block">t = \frac{\log \left(P/P_o\right)}{\log \alpha}</math>

where <math>t</math> is the number of years, <math>P</math> is a parameter that increases annually as a function of <math>P_o</math> and of <math>t</math> according to <math>P = P_o \alpha^t</math> and <math>\alpha</math>, a growth rate.

If <math>\alpha = 1.04</math>, then humanity's energy consumption will exceed the incident solar power (1.742 × 10¹⁷ <abbr>W</abbr>) after 240 years, the total power of the Sun (3.826 × 10²⁶ <abbr>W</abbr>) after 800 years, and that of the Galaxy (7.29 × 10³⁶ <abbr>W</abbr>) after 1,500 years. Kardashev concludes that the current exponential growth is a transitional phase in the development of a civilization, and that it is inevitably limited by natural factors. In fact, he believes that the required mass and energy will continue to grow exponentially for another 1,000 years.

Research conducted

In 1963, Nikolai Kardashev and Gennady Borissovich Sholomitskii studied the CTA 102 radio source on the 920&nbsp;MHz band from the Crimea Deep Space Station, looking for signs of a Type&nbsp;III civilization. CTA 102 had been discovered by Sholomitskii a year earlier, and Kardashev quickly saw it as a possible artificial source to study in order to validate his classification. The observation lasted until February 1965, and on April 12, Sholomitskii announced to the press (via the Russian ITAR-TASS) that Soviet astronomers had discovered a signal that could be of extraterrestrial origin. On April 14, he gave a conference in Moscow where he repeated his announcement; but by November 1964, two American astronomers had identified CTA 102 as a quasar, and their publication definitively closed the "CTA 102 case". It was the study of this source that had led to the Byurakan conference in 1964.

In 1975 and 1976, the American astronomers Frank Drake and Carl Sagan searched at Arecibo for signs of Type&nbsp;II civilizations in four galaxies of the Local Group: M33, M49, Leo I and Leo II. The year before, the two men had sent mankind's first message to M13. The results were published as "The Search for Extraterrestrial Intelligence" in Scientific American in May 1975.

In 1976, Kardashev, Troitskii, and Gindilis used the RATAN-600 radio telescope in the North Caucasus to search for signals from Type&nbsp;II or III civilizations in the Milky Way and other nearby galaxies.

A small-scale search for possible Type&nbsp;III sources was conducted by James Annis in 1999 and published in the Journal of the British Interplanetary Society under the title "Placing a limit on star-fed Kardashev type III civilizations". An astrophysicist at Fermilab (US), Annis studied a sample of 31 galaxies, both spiral and elliptical, using the Tully-Fisher diagram, in which the absolute magnitude is a function of the galaxies' rotational speed. Annis suggested that 75% of the least luminous objects (i.e., those with a decrease in absolute magnitude of 1.5 compared to the diagram) could be considered as possible candidates. However, no object with this characteristic is observed in his survey.

Per Calissendorff conducted a study on a sample of spiral galaxies from two databases: 4,861 from the Spiral Field I-band (SFI++ catalog compiled by Springob et al. in 2005) and 95 from that of Reyes et al. in 2011.

In 2016, Paul Gilster, author of the Centauri Dreams website, described a signal apparently coming from the star HD 164595 as requiring the power of a Type&nbsp;I or Type&nbsp;II civilization, if produced by extraterrestrial lifeforms. In August 2016, however, it was discovered that the origin of the signal was most likely a military satellite orbiting the Earth.

Possible listening criteria

Kardashev's point of view

According to Kardashev, humanity's ignorance of the physical possibilities of communication through space is great.

Other leads

For Samuil Aronovich Kaplan, "the most reliable criterion" remains the small angular diameter of the radio source. The wavelength of 21&nbsp;cm, privileged since 1959, according to the study of Cocconi and Morrison, is not the only listening region. Kaplan, in 1971, also mentioned the radio region of the spectrum, characterized by the hydroxyl radical (OH). For Livio, the means of detection should focus on globular clusters, the regions most likely to harbor planets similar to the Earth.

Criticisms of the classification

William I. Newman and Carl Sagan believe that the growth of energy consumption alone cannot describe the evolution of civilizations; it is also necessary to consider population growth, and in particular the fact that it can be limited by the transport capacity of interplanetary means of travel. They conclude that there can be no ancient civilizations of galactic dimensions, nor galactic empires, although the possibility of networks of colonized worlds (of about 5 to 10 planets) is strong.

The scale theorized by Kardashev was born in the geopolitical context of the Cold War, in which energy had supreme value. civilizations more important than ours must be so rare that they do not have the possibility to dominate and be visible.

1. Finally, research and listening programs in Harvard University and Buenos Aires (Horowitz and Sagan in 1993 or Lemarchand et al. in 1997) have not provided any scientific proof of the existence of artificial sources, neither in the Milky Way nor in nearby galaxies (M33, M81, the Whirlpool Galaxy or Centaurus A), or even in the Virgo cluster.

For the British meteorologist Lewis Fry Richardson, author of a statistical study on mortality (published in Statistics of Deadly Quarrels, 1960), man's aggressiveness does not allow us to predict a life span that will allow humanity to reach more evolved stages. He estimates that man's violent impulses will destroy the social order over a period of 1000 years. Moreover, mankind will probably be destroyed with weapons of mass destruction within a few centuries at the most.

Transhumanists Paul Hughes and John Smart explain the absence of signals from a Type&nbsp;III civilization with two hypotheses: either it has self-destructed or it has not followed the trajectory described by Kardashev. In summary, the impossibility of sustainably securing energy resources may explain the absence of Type&nbsp;II and III civilizations.

Energy development

Type&nbsp;I civilization methods

• Large-scale application of fusion power: In terms of mass–energy equivalence, Type&nbsp;I implies the conversion of about 2&nbsp;kg of matter to energy per second. An equivalent energy release could theoretically be achieved by fusing about 280&nbsp;kg of hydrogen into helium per second, a rate roughly equivalent to 8.9&nbsp;kg/year. One cubic kilometer of water contains about &nbsp;kg of hydrogen, and the Earth's oceans contain about 1.3&nbsp;cubic kilometers of water, meaning that humans on Earth could sustain this rate of consumption over geological time scales, in terms of available hydrogen.
• Antimatter in large quantities would provide a mechanism to produce power on a scale several orders of magnitude beyond the current level of technology. In antimatter-matter collisions, all of the rest mass of the particles is converted to radiant energy. Their energy density (energy released per mass) is about four orders of magnitude greater than that from using nuclear fission, and about two orders of magnitude greater than the best possible yield from fusion. The reaction of 1&nbsp;kg of antimatter with 1&nbsp;kg of matter would produce 1.8&nbsp;J (180 petajoules) of energy. Although antimatter is sometimes proposed as a source of energy, this does not seem feasible. Artificially producing antimatter – according to current understanding of the laws of physics – involves first converting energy into mass, which yields no net energy. Artificially created antimatter is usable only as an energy storage medium, not as an energy source, unless future technological developments (contrary to the conservation of the baryon number, such as a CP violation in favor of antimatter) allow the conversion of ordinary matter into anti-matter. Theoretically, humans may be able to cultivate and harvest a number of naturally occurring sources of antimatter in the future.
• Renewable energy by converting sunlight into electricity – either directly through solar cells and concentrating solar power, or indirectly through biofuels, wind, and hydroelectric power: There is no known way for a human civilization to harness the equivalent of the Earth's total absorbed solar energy without completely covering the surface with man-made structures, which is not feasible with current technology. However, if a civilization constructed very large space-based solar power satellites, Type&nbsp;I power levels might become achievable—these could convert sunlight to microwave power and beam it to collectors on Earth.

Type&nbsp;II civilization methods

right|thumb|A figure of a [[Dyson Swarm|Dyson swarm surrounding a star|alt=]]

• Type&nbsp;II civilizations could use the same techniques as a Type&nbsp;I civilization, but applied to a large number of planets in a large number of star systems.
• A Dyson sphere or Dyson swarm and similar constructs are hypothetical megastructures originally described by Freeman Dyson as a system of orbiting solar power satellites designed to completely encircle a star and capture most or all of its energy output.
• Another means of generating usable energy would be to feed a stellar mass into a black hole, and collect the photons emitted by the accretion disk. A less exotic means would be to simply capture photons already escaping from the accretion disk, thereby reducing a black hole's angular momentum; this is known as the Penrose process. However, this may only be possible for a Type&nbsp;III civilization.
• Star lifting is a process by which an advanced civilization could remove a substantial portion of a star's matter in a controlled manner for other uses.
• Antimatter is likely to be produced as an industrial byproduct of a number of megascale engineering processes (such as the aforementioned star lifting), and could therefore be recycled.
• In multiple star systems with a sufficiently large number of stars: absorbing a small but significant fraction of the output of each individual star.
• Stellar engines can be used to move stars.

Type&nbsp;III civilization methods

• Type&nbsp;III civilizations might use the same techniques as a Type&nbsp;II civilization, but applied individually to all possible stars in one or more galaxies.
• White holes could theoretically provide large amounts of energy by collecting the matter ejected outward.
• Capturing the energy of gamma-ray bursts is another theoretically possible power source for an advanced civilization.
• The emissions from quasars are comparable to those from small active galaxies and could be a massive power source if they could be collected.

Civilization implications

There are many historical examples of human civilization undergoing large-scale transitions, such as the Industrial Revolution. The transitions between Kardashev scale levels could potentially represent similarly dramatic periods of social upheaval, as they involve exceeding the hard limits of the resources available within a civilization's existing territory. A common speculation is that the transition from Type&nbsp;0 to Type&nbsp;I could carry a strong risk of self-destruction, since in some scenarios there would be no room for further expansion on the civilization's home planet, as in a Malthusian catastrophe.

For example, excessive energy consumption without adequate heat removal could plausibly render the planet of a Type I approaching civilization unsuitable for the biology of the dominant life forms and their food sources. Using Earth as an example, ocean temperatures above 95&nbsp;°F (35&nbsp;°C) would endanger marine life and make it difficult, if not impossible, for mammals to cool to temperatures suitable for their metabolism. Of course, these theoretical speculations may not become problems, possibly through the application of future engineering and technology. Also, by the time a civilization reaches Type&nbsp;I, it may have colonized other planets or established O'Neill-type colonies, so that waste heat could be distributed throughout the star system.

The limitations of biological life forms and the evolution of computer technology may lead to the transformation of the civilization through mind uploading and artificial general intelligence in general during the transition from Type&nbsp;I to Type&nbsp;II, leading to a digitized civilization.

See also

• Astronomical engineering
• Clarke's three laws
• Drake equation
• Dyson sphere
• Gerhard Lenski
• Great Filter
• HD 164595
• Orders of magnitude (energy)
• Orders of magnitude (power)
• Quiet and loud aliens
• Tabby's Star (KIC 8462852)
• Terraforming
• White's law
• World energy supply and consumption

Notes

References

Further reading

• Dyson, Freeman J. Energy in the Universe Article in September 1971 Scientific American magazine (Special September Issue on Energy)
• Wind Powering America
• Clean Energy for Planetary Survival: International Development Research Centre
• LBL Scientists Research Global Warming
• E³ Handbook
• Clarke H2 energy systems
• Shkadov Thruster
• Supercivilizations as Possible Products of the Progressive Evolution of Matter: also by Kardashev
• Search for Artificial Stellar Sources of Infrared Radiation, by Freeman J. Dyson
• The Radio Search For Intelligent Extraterrestral Life, by Frank Drake

External links

• by Universe Today.
• from Dr. Michio Kaku.
• by Space.com.
• by Kurzgesagt, explaining and visualizing the topic.
• , an audio podcast by SciFi Thoughts.
• , and visual simulator of the Kardashev Scale by Davide Volpato.