Great Filter
The Great Filter is the idea that, in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there is a barrier to development that makes detectable extraterrestrial life exceedingly rare.[1][2] The Great Filter is one possible resolution of the Fermi paradox.
The concept originates in Robin Hanson's argument that the failure to find any extraterrestrial civilizations in the observable universe implies that something is wrong with one or more of the arguments (from various scientific disciplines) that the appearance of advanced intelligent life is probable; this observation is conceptualized in terms of a "Great Filter" which acts to reduce the great number of sites where intelligent life might arise to the tiny number of intelligent species with advanced civilizations actually observed (currently just one: human).[3] This probability threshold, which could lie in the past or following human extinction, might work as a barrier to the evolution of intelligent life, or as a high probability of self-destruction.[1][4] The main conclusion of this argument is that the easier it was for life to evolve to the present stage, the bleaker the future chances of humanity probably are.
The idea was first proposed in an online essay titled "The Great Filter – Are We Almost Past It?", written by economist Robin Hanson. The first version was written in August 1996 and the article was last updated on September 15, 1998[update]. Hanson's formulation has received recognition in several published sources discussing the Fermi paradox and its implications.
Main argument
Fermi paradox
There is no reliable evidence that
Our planet and solar system, however, don't look substantially colonized by advanced competitive life from the stars, and neither does anything else we see. To the contrary, we have had great success at explaining the behavior of our planet and solar system, nearby stars, our galaxy, and even other galaxies, via simple "dead" physical processes, rather than the complex purposeful processes of advanced life.
Life is expected to expand to fill all available niches.[5] With technology such as self-replicating spacecraft, these niches would include neighboring star systems and even, on longer time scales which are still small compared to the age of the universe, other galaxies. Hanson notes, "If such advanced life had substantially colonized our planet, we would know it by now."[1]
The Great Filter
With no evidence of intelligent life in places other than Earth, it appears that the process of starting with a star and ending with "advanced explosive lasting life" must be unlikely. This implies that at least one step in this process must be improbable. Hanson's list, while incomplete, describes the following nine steps in an "evolutionary path" that results in the colonization of the observable universe:
- The right star system (including organics and potentially habitable planets)
- Reproductive molecules (e.g. RNA)
- Simple (single-cell life
- Complex (eukaryotic) single-cell life
- Sexual reproduction
- Multi-cell life
- Tool-using animals with intelligence
- A civilization advancing toward the potential for a colonization explosion (where we are now)
- Colonization explosion
According to the Great Filter hypothesis, at least one of these steps—if the list were complete—must be improbable. If it is not an early step (i.e., in the past), then the implication is that the improbable step lies in the future and humanity's prospects of reaching step 9 (interstellar colonization) are still bleak. If the past steps are likely, then many civilizations would have developed to the current level of the human species. However, none
Although steps 1–8 have occurred on Earth, any one of these may be unlikely. If the first seven steps are necessary preconditions to calculating the likelihood (using the
In a 2020 paper, Jacob Haqq-Misra, Ravi Kumar Kopparapu, and Edward Schwieterman argued that current and future telescopes searching for
In a specific formulation named the "
Responses
There are many alternative scenarios that might allow for the evolution of intelligent life to occur multiple times without either catastrophic self-destruction or glaringly visible evidence. These are possible resolutions to the Fermi paradox: "They do exist, but we see no evidence". Other ideas include: it is too expensive to spread physically throughout the galaxy; Earth is purposely isolated; it is dangerous to communicate and hence civilizations actively hide, among others.
Astrobiologists
Astronomer
This is, of course, a variant on the Fermi paradox: We don't see clues to widespread, large-scale engineering, and consequently we must conclude that we're alone. But the possibly flawed assumption here is when we say that highly visible construction projects are an inevitable outcome of intelligence. It could be that it's the engineering of the small, rather than the large, that is inevitable. This follows from the laws of inertia (smaller machines are faster, and require less energy to function) as well as the speed of light (small computers have faster internal communication). It may be—and this is, of course, speculation—that advanced societies are building small technology and have little incentive or need to rearrange the stars in their neighborhoods, for instance. They may prefer to build nanobots instead. It should also be kept in mind that, as Arthur C. Clarke said, truly advanced engineering would look like magic to us—or be unrecognizable altogether. By the way, we've only just begun to search for things like Dyson spheres, so we can't really rule them out.[10][11]
See also
- Black swan theory – Theory of response to surprise events
- Doomsday argument – Doomsday scenario on human births
- Drake equation – Estimate of extraterrestrial civilizations
- Anthropic principle – Hypothesis about sapient life and the universe
- Global catastrophic risk – Potentially harmful worldwide events
- Goldilocks principle – Analogy for optimal conditions
- Inverse gambler's fallacy – Formal fallacy of Bayesian inference
- Kardashev scale – Measure of a civilization's evolution
- Neocatastrophism – Hypothesis for lack of detected aliens
- Principle of mediocrity – Philosophical concept
- Quiet and loud aliens – Concept in astrobiology
- Rare Earth hypothesis – Hypothesis that complex extraterrestrial life is improbable and extremely rare
- Selection bias – Bias in a statistical analysis due to non-random selection
References
- ^ a b c d Hanson, Robin (1998). "The Great Filter – Are We Almost Past It?". Archived from the original on 2010-05-07.
- New York Times. Archivedfrom the original on September 19, 2019. Retrieved October 29, 2015.
- ^ Hanson 1998: "No alien civilizations have substantially colonized our solar system or systems nearby. Thus among the billion trillion stars in our past universe, none has reached the level of technology and growth that we may soon reach. This one data point implies that a Great Filter stands between ordinary dead matter and advanced exploding lasting life. And the big question is: How far along this filter are we?"
- ^ Technology Review. Massachusetts Institute of Technology: 72–77. Archived(PDF) from the original on 2019-12-24. Retrieved 2008-06-19.
- Bibcode:1978QJRAS..19..277P. Archivedfrom the original on 2022-11-08. Retrieved 2022-11-08.
- .
- S2CID 211204863.
- ^ Williams, Matt (23 August 2020). "Beyond "Fermi's Paradox" VI: What is the Berserker Hypothesis?". Universe Today. Archived from the original on 18 October 2022. Retrieved 18 October 2022.
- ISBN 978-3-319-62045-9. Archivedfrom the original on 2023-03-31. Retrieved 2020-02-26.
- ^ a b Pethokoukis, James M. (2003-11-04). "Keeping His Eyes on the Skies". U.S. News & World Report. Archived from the original on 2013-06-19.
- ^ Joseph Voros in "Macro-Perspectives Beyond the World System" (2007) points out that some researchers have attempted to search for energy signatures that could be traced to Dyson-like structures (shells, swarms, or spheres). So far, none have been found. See for example, Tilgner & Heinrichsen, "A Program to Search for Dyson Spheres with the Infrared Space Observatory", Acta Astronautica Vol. 42 (May–June, 1998), pp. 607–612; and Timofeev et al. "A search of the IRAS database for evidence of Dyson Spheres", Acta Astronautica Vol. 46, (June 2000), pp. 655–659.
Further reading
- Journal of Evolution and Technology. 9.
- Ćirković, Milan M.; Vesna Milosevic-Zdjelar (2003). "Extraterrestrial Intelligence and Doomsday: A Critical Assessment of the No-Outsider Requirement" (PDF). Serbian Astronomical Journal. 166 (166): 1–11. .
- Ćirković, Milan M. (2004-08-27). "Permanence - An Adaptationist Solution to Fermi's Paradox?". Journal of the British Interplanetary Society. 58: 62. Bibcode:2005JBIS...58...62C.
- Ćirković, Milan M.; Robert J. Bradbury (Jul 2006). "Galactic Gradients, Postbiological Evolution and the Apparent Failure of SETI". S2CID 1540494.
- Ćirković, Milan M. (Jul 2008). "Against the Empire". Bibcode:2008JBIS...61..246C.
- Ćirković, Milan M. (2008). "Observation selection effects and global catastrophic risks". In Nick Bostrom; Milan M. Ćirković (eds.). Global Catastrophic Risks. Oxford University Press.
- Sentient Developments.
- Hanlon, Michael (2008). Eternity: Our Next Billion Years. ISBN 978-0-230-21931-1.