Active SETI (Active Search for Extra-Terrestrial Intelligence) is the attempt to send messages to intelligent extraterrestrial life. Active SETI messages are predominantly sent in the form of radio signals. Physical messages like that of the Pioneer plaque may also be considered an active SETI message. Active SETI is also known as METI (Messaging to Extra-Terrestrial Intelligence). [1] [2]
'Active SETI' was a term as early as 2005, though some decades after the term SETI. [3] The term METI was coined in 2006 by Russian scientist Alexander Zaitsev, who proposed a subtle distinction between Active SETI and METI: [4] [5]
The science known as SETI deals with searching for messages from aliens. METI deals with the creation and transmission of messages to aliens. Thus, SETI and METI proponents have quite different perspectives. SETI scientists are in a position to address only the local question “does Active SETI make sense?” In other words, would it be reasonable, for SETI success, to transmit with the object of attracting ETI's attention? In contrast to Active SETI, METI pursues not a local, but a more global purpose – to overcome the Great Silence in the Universe, bringing to our extraterrestrial neighbors the long-expected annunciation “You are not alone!”
Concern over METI was raised by the science journal Nature in an editorial in October 2006, which commented on a recent meeting of the International Academy of Astronautics SETI study group. The editor said, "It is not obvious that all extraterrestrial civilizations will be benign, or that contact with even a benign one would not have serious repercussions". [6] In the same year, astronomer and science fiction author David Brin expressed similar concerns. [7] In 2013 Brin amended his initial article based on the recent developments in METI. [8]
In 2010, Douglas A. Vakoch from SETI Institute, addressed concerns about the validity of Active SETI alone as an experimental science by proposing the integration of Active SETI and Passive SETI programs to engage in a clearly articulated, ongoing, and evolving set of experiments to test various versions of the Zoo hypothesis, including specific dates at which a first response to messages sent to particular stars could be expected. [9]
On 13 February 2015, scientists including Douglas Vakoch, David Grinspoon, Seth Shostak, and David Brin at an annual meeting of the American Association for the Advancement of Science discussed Active SETI, and whether transmitting a message to possible intelligent extraterrestrials in the Cosmos was a good idea. [10] [11] That same week, a statement was released, signed by many in the SETI community including Berkeley SETI Research Center director Andrew Siemion, advocating that a "worldwide scientific, political and humanitarian discussion must occur before any message is sent". [12]
In July 2015, the Breakthrough Message program was announced. This was an open competition to design a digital message that could be transmitted from Earth to an extraterrestrial civilization, with a US$1,000,000 prize pool. The message was to be "representative of humanity and planet Earth". The program pledged "not to transmit any message until there has been a wide-ranging debate at high levels of science and politics on the risks and rewards of contacting advanced civilizations". [13]
In the paper Rationale for METI, [14] transmission of the information into the Cosmos is treated as one of the pressing needs of an advanced civilization. This view is not universally accepted, and it is not agreed with by those who are against the transmission of interstellar radio messages, but at the same time are not against SETI searching. Such duality is called the SETI Paradox. [15] [16]
The lack of an established communications protocol is a challenge for METI. While trying to synthesize and project an Interstellar Radio Message (IRM), the receiving extraterrestrials (ETs) will first encounter a physical phenomenon and, only after that, perceive the information. Initially, a receiving system will detect the radio signal; then the issue of the extraction of the received information and comprehension of the obtained message will arise. Therefore, above all, the constructor of an IRM should be concerned about the ease of signal determination. In other words, the signal should have maximum openness, which is understood here as an antonym of the term security. This branch of signal synthesis is termed anticryptography.
To this end, in 2010, Michael W. Busch created a general-purpose binary language, [17] later used in the Lone Signal project [18] to transmit crowdsourced messages to extraterrestrial intelligence. [19] Busch developed the coding scheme and provided Rachel M. Reddick with a test message, in a blind test of decryption. [17] Reddick decoded the entire message after approximately twelve hours of work. [17] This was followed by an attempt to extend the syntax used in the Lone Signal hailing message to communicate in a way that, while neither mathematical nor strictly logical, was nonetheless understandable given the prior definition of terms and concepts in the hailing message. [20]
In addition, characteristics of the radio signal, such as wavelength, type of polarization, and modulation are considered. Over galactic distances, the interstellar medium induces some scintillation effects and artificial modulation of electromagnetic signals. This modulation is higher at lower frequencies and is a function of the sky direction. Over large distances, the depth of the modulation can exceed 100%, making any METI signal very difficult to decode.
In METI research, any message must have some redundancy, although the exact amount of redundancy and message formats are still in great dispute. Using ideograms, instead of binary sequence, already offers some improvement against noise resistance. In faxlike transmissions, ideograms are spread on many lines. This increases its resistance against short bursts of noise like radio frequency interference or interstellar scintillation.
One format approach proposed for interstellar messages was to use the product of two prime numbers to construct an image. Unfortunately, this method works only if all the bits are present. As an example, the message sent by Frank Drake from the Arecibo Observatory in 1974 did not have any feature to support mechanisms to cope with the inevitable noise degradation of the interstellar medium.
Error correction tolerance rates for previous METI messages are 9% (one page) for the 1974 Arecibo Message, 44% (23 separate pages) for the 1999 Evpatoria Message, and 46% (one page, estimated) for the 2003 Evpatoria Message.
The 1999 Cosmic Call transmission was far from being optimal (from a terrestrial viewpoint) as it was essentially a monochromatic signal spiced with supplementary information. Additionally, the message had a very small modulation index overall, a condition not viewed as being optimal for interstellar communication. Over the 370,967 bits (46,371 bytes) sent, some 314,239 were “1” and 56,768 were “0”—5.54 times as many 1's as 0's. Since frequency-shift keying modulation scheme was used, most of the time the signal was on the “0” frequency. In addition, “0” tended to be sent in long stretches, which appeared as white lines in the message.
The below projects have targeted stars between 17 and 69 light-years from the Earth. The exception is the Arecibo message, which targeted globular cluster M13, approximately 24,000 light-years away. The first interstellar message to reach its destination was the Altair (Morimoto - Hirabayashi) Message, which likely reached its target in 1999. [21]
Below is a table of messages sent and target/destination stars, ordered chronologically by date of sending: [24] [25] [26] [27] [28] [29]
| Name | Designation | Constellation | Date sent (YYYY-MM-DD) | Arrival date (YYYY-MM-DD) | Message |
|---|---|---|---|---|---|
| Messier 13 | NGC 6205 | Hercules | 1974-11-16 | 27000~ | Arecibo Message |
| Altair | Alpha Aql | Aquila | 1983-08-15 | 2017 | CALL to the COSMOS'83 [30] |
| Libra | Libra | 1995 | NASDA Cosmic-College | ||
| 1996 | NASDA Cosmic-College | ||||
| Spica | Alpha Vir | Virgo | 1997-08 | 2247 | NASDA Cosmic-College |
| 1998 | NASDA Cosmic-College | ||||
| 16 Cyg A | HD 186408 | Cygnus | 1999-05-24 | 2069-11 | Cosmic Call 1 |
| 15 Sge | HD 190406 | Sagitta | 1999-06-30 | 2057-02 | |
| HD 178428 | 2067-10 | ||||
| Gl 777 | HD 190360 | Cygnus | 1999-07-01 | 2051-04 | |
| HD 197076 | Delphinus | 2001-08-29 | 2070-02 | Teen Age Message | |
| 47 UMa | HD 95128 | Ursa Major | 2001-09-03 | 2047-07 | |
| 37 Gem | HD 50692 | Gemini | 2057-12 | ||
| HD 126053 | Virgo | 2001-09 | 2059-01 | ||
| HD 76151 | Hydra | 2001-09-04 | 2057-05 | ||
| HD 193664 | Draco | 2059-01 | |||
| HIP 4872 | Cassiopeia | 2003-07-06 | 2036-04 | Cosmic Call 2 | |
| HD 245409 | Orion | 2040-08 | |||
| 55 Cnc | HD 75732 | Cancer | 2044-05 | ||
| HD 10307 | Andromeda | 2044-09 | |||
| 47 UMa | HD 95128 | Ursa Major | 2049-05 | ||
| Polaris | HIP 11767 | Ursa Minor | 2008-02-04 | 2439 | Across the Universe |
| Gliese 581 | HIP 74995 | Libra | 2008-10-09 | 2029 | A Message From Earth |
| 2009-08-28 | 2030 | Hello From Earth | |||
| GJ 83.1 | GJ 83.1 | Aries | 2009-11-07 | 2024 | RuBisCo Stars |
| Teegarden's Star | SO J025300.5+165258 | 2022 | |||
| Kappa1 Ceti | GJ 137 | Cetus | 2039 | ||
| HIP 34511 | Gemini | 2012-08-15 | 2163 | Wow! Reply | |
| 37 Gem | HD 50692 | 2069 | |||
| 55 Cnc | HD 75732 | Cancer | 2053 | ||
| GJ 526 | HD 119850 | Boötes | 2013-07-10 | 2031 | Lone Signal |
| 55 Cnc | HD 75732 | Cancer | 2013-09-22 | 2053 | JAXA Space Camp (UDSC-1) |
| 55 Cnc | HD 75732 | Cancer | 2014-08-23 | 2054 | JAXA Space Camp (UDSC-2) |
| Polaris | HIP 11767 | Ursa Minor | 2016-10-10 | 2450 | A Simple Response to an Elemental Message |
| Luyten's Star | HIP 36208 | Canis Major | 2017-10-16 | 2030-03 | Sónar Calling GJ273b |
Whether or not to conduct Active SETI, as well as the tone of any message, is a highly controversial topic. [31] [32] [33] [34] Active SETI has primarily been criticized due to the perceived risk of revealing the location of the Earth to alien civilizations, without some process of prior international consultation. That is, Active SETI does not meet the criteria for informed consent in a mass experiment involving human subjects and, potentially, nonhuman sentient subjects. [35]
Active SETI is discussed in terms of the ethics of space policy. Issues include whether to send belligerent versus defensive messages, [36] cosmopolitanism, [37] communicative burden, consensus, messaging content, proscriptions on premature messaging, responsibility, and shared values, [38] with concerns that even if successful, humanity could be reduced to a cargo cult. [39] David Brin also urged for an extensive international consultation before any METI activities and has debunked key rationalizations for active SETI (METI), such as the "barn door" argument (unintentional "leaked signals" were millions-fold weaker than intentional METI signals), ignoring/dismissing the precautionary principle (that requires taking extreme precaution e.g. handling extraterrestrial samples even without any known example of risks), and treating METI as being prayer-like which disregards the issue of informed consent from other people. [40] Notable among METI's critics was Stephen Hawking. Hawking, who in his book A Brief History of Time suggests that "alerting" extraterrestrial intelligences to our existence is foolhardy, citing humankind's history of treating its own kind harshly in meetings of civilizations with a significant technology gap, e.g., the extermination of Tasmanian aborigines. He suggested, in view of this history, that we "lay low". [41] Scientist and science fiction author David Brin expressed similar concerns. [42] Similarly, Liu Cixin's trilogy of novels The Three Body Problem highlights the potential dangers of METI.
However, some scientists consider these fears about the dangers of METI as panic and irrational superstition; Russian and Soviet radio engineer and astronomer Alexander L. Zaitsev has argued against these concerns. [43] [44] Zaitsev argues that we should consider the risks of not attempting to contact extraterrestrial civilizations, since the knowledge and wisdom an ETI could impart to us would save us from humanity's self-destructive tendencies. [45] Similarly, in a March 2015 essay astronomer Seth Shostak considered the risk and ended by stressing that any danger was hypothetical and that humanity would better off risk contact than "endlessly tremble at the sight of the stars". [2]
Astronomer Jill Tarter also disagrees with Hawking, arguing that aliens developed and long-lived enough to communicate and travel across interstellar distances would have evolved a cooperative and less violent intelligence. She however thinks it is too soon for humans to attempt active SETI and that humans should be more advanced technologically first but keep listening in the meantime. [46]
To lend a quantitative basis to discussions of the risks of transmitting deliberate messages from Earth, the SETI Permanent Study Group of the International Academy of Astronautics [47] adopted in 2007 a new analytical tool, the San Marino Scale. [48] Developed by Prof. Ivan Almar and Prof. H. Paul Shuch, the San Marino Scale evaluates the significance of transmissions from Earth as a function of signal intensity and information content. Its adoption suggests that not all such transmissions are created equal, thus each must be evaluated separately before establishing a blanket international policy regarding Active SETI. [49]
In 2012, Jacob Haqq-Misra, Michael Busch, Sanjoy Som, and Seth Baum argued that while the benefits of radio communication on Earth likely outweigh the potential harms of detection by extraterrestrial watchers, the uncertainty regarding the outcome of contact with extraterrestrial beings creates difficulty in assessing whether or not to engage in long-term and large-scale METI. [50]
In 2015, in the context of the Zoo Hypothesis, biologist João Pedro de Magalhães proposed transmitting an invitation message to any extraterrestrial intelligences watching us already and inviting them to respond, arguing this would not put us in any more danger than we are already if the Zoo Hypothesis is correct. [51]
Douglas Vakoch, president of METI, argues that passive SETI itself is already an endorsement of active SETI, since "If we detect a signal from aliens through a SETI program, there's no way to prevent a cacophony of responses from Earth." [52]
In the context of potentially detected extraterrestrial activity on Earth, physicist Mark Buchanan argued that humanity needs to determine whether it would be safe or wise to attempt to communicate with extraterrestrials and work on ways to handle such attempts in an organized manner. [53]
One proposal for a 10 billion watt interstellar SETI beacon was dismissed by Robert A. Freitas Jr. as being infeasible for a pre-Type I civilization, such as humanity, on the Kardashev scale. [54] However, this 1980s technical argument assumes omni-directional beacons, which may not be the best way to proceed on many technical grounds. Advances in consumer electronics have made possible transmitters that simultaneously transmit many narrow beams, covering the million or so nearest stars but not the spaces between. [55] This multibeam approach can reduce the power and cost to levels that are reasonable with early 21st century Earth technology.
Once civilizations have discovered each other's locations, the energy requirements for maintaining contact and exchanging information can be significantly reduced through the use of highly directional transmission technologies. To this end, a 2018 study estimated a 1-2 megawatt infrared laser focused through a 30-45 meter telescope could be seen from about 20,000 light years away. [56]
The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy.
The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. As a 2015 article put it, "If life is so easy, someone from somewhere must have come calling by now."
The search for extraterrestrial intelligence (SETI) is a collective term for scientific searches for intelligent extraterrestrial life, for example, monitoring electromagnetic radiation for signs of transmissions from civilizations on other planets.
Frank Donald Drake was an American astrophysicist and astrobiologist.
Extraterrestrial intelligence (ETI) refers to hypothetical intelligent extraterrestrial life. No such life has ever been verifiably observed to exist. The question of whether other inhabited worlds might exist has been debated since ancient times. The modern form of the concept emerged when the Copernican Revolution demonstrated that the Earth was a planet revolving around the Sun, and other planets were, conversely, other worlds. The question of whether other inhabited planets or moons exist was a natural consequence of this new understanding. It has become one of the most speculative questions in science and is a central theme of science fiction and popular culture.
The SETI Institute is a not-for-profit research organization incorporated in 1984 whose mission is to explore, understand, and explain the origin and nature of life in the universe, and to use this knowledge to inspire and guide present and future generations, sharing knowledge with the public, the press, and the government. SETI stands for the "search for extraterrestrial intelligence".
The Wow! signal was a strong narrowband radio signal detected on August 15, 1977, by Ohio State University's Big Ear radio telescope in the United States, then used to support the search for extraterrestrial intelligence. The signal appeared to come from the direction of the constellation Sagittarius and bore expected hallmarks of extraterrestrial origin.
The communication with extraterrestrial intelligence (CETI) is a branch of the search for extraterrestrial intelligence (SETI) that focuses on composing and deciphering interstellar messages that theoretically could be understood by another technological civilization. The best-known CETI experiment of its kind was the 1974 Arecibo message composed by Frank Drake.
The Teen Age Message (TAM) was a series of interstellar radio transmissions sent from the Yevpatoria Planetary Radar to six solar-type stars during August–September 2001. The structure of the TAM was suggested by Alexander Zaitsev, Chief Scientist at Russia's Institute of Radio-engineering and Electronics. The message's content and target stars were selected by a group of teens from four Russian cities, who collaborated in person and via the Internet. Each transmission comprised three sections: a sounding, a live theremin concert, and digital data including images and text. TAM was humanity's fourth Active SETI broadcast and the first musical interstellar radio message.
Aleksandr Leonidovich Zaitsev was a Russian and Soviet radio engineer and astronomer from Fryazino. He worked on radar astronomy devices, near-Earth asteroid radar research, and SETI.
A post-detection policy (PDP), also known as a post-detection protocol, is a set of structured rules, standards, guidelines, or actions that governmental or other organizational entities plan to follow for the "detection, analysis, verification, announcement, and response to" confirmed signals from extraterrestrial civilizations. Though no PDPs have been formally and openly adopted by any governmental entity, there is significant work being done by scientists and nongovernmental organizations to develop cohesive plans of action to utilize in the event of detection. The most popular and well known of these is the "Declaration of Principles Concerning Activities Following the Detection of Extraterrestrial Intelligence", which was developed by the International Academy of Astronautics (IAA), with the support of the International Institute of Space Law. The theories of PDPs constitute a distinct area of research but draw heavily from the fields of SETI, METI, and CETI.
The cultural impact of extraterrestrial contact is the corpus of changes to terrestrial science, technology, religion, politics, and ecosystems resulting from contact with an extraterrestrial civilization. This concept is closely related to the search for extraterrestrial intelligence (SETI), which attempts to locate intelligent life as opposed to analyzing the implications of contact with that life.
Lone Signal was a crowdfunded active SETI project designed to send interstellar messages from Earth to a possible extraterrestrial civilization. Founded by businessman Pierre Fabre and supported by several entrepreneurs, Lone Signal was based at the Jamesburg Earth Station in Carmel, California.
Technosignature or technomarker is any measurable property or effect that provides scientific evidence of past or present technology. Technosignatures are analogous to biosignatures, which signal the presence of life, whether intelligent or not. Some authors prefer to exclude radio transmissions from the definition, but such restrictive usage is not widespread. Jill Tarter has proposed that the search for extraterrestrial intelligence (SETI) be renamed "the search for technosignatures". Various types of technosignatures, such as radiation leakage from megascale astroengineering installations such as Dyson spheres, the light from an extraterrestrial ecumenopolis, or Shkadov thrusters with the power to alter the orbits of stars around the Galactic Center, may be detectable with hypertelescopes. Some examples of technosignatures are described in Paul Davies's 2010 book The Eerie Silence, although the terms "technosignature" and "technomarker" do not appear in the book.
Breakthrough Initiatives is a science-based program founded in 2015 and funded by Julia and Yuri Milner, also of Breakthrough Prize, to search for extraterrestrial intelligence over a span of at least 10 years. The program is divided into multiple projects. Breakthrough Listen will comprise an effort to search over 1,000,000 stars for artificial radio or laser signals. A parallel project called Breakthrough Message is an effort to create a message "representative of humanity and planet Earth". The project Breakthrough Starshot, co-founded with Mark Zuckerberg, aims to send a swarm of probes to the nearest star at about 20% the speed of light. The project Breakthrough Watch aims to identify and characterize Earth-sized, rocky planets around Alpha Centauri and other stars within 20 light years of Earth. Breakthrough plans to send a mission to Saturn's moon Enceladus, in search for life in its warm ocean, and in 2018 signed a partnership agreement with NASA for the project.
A Simple Response to an Elemental Message (ASREM) was an Interstellar Radio Message (IRM) consisting primarily of 3775 worldwide responses to this initiative's posed question; "How will our present, environmental interactions shape the future?" This transmission also features a smaller 'Honorary Mention' text archive and a series of images of Earth.
METI International, known simply as METI, is a non-profit research organization founded in July 2015 by Douglas Vakoch that creates and transmits interstellar messages to attempt to communicate with extraterrestrial civilizations. It is based in San Francisco, California.
Douglas A. Vakoch is an American astrobiologist, search for extraterrestrial intelligence (SETI) researcher, psychologist, and president of METI International, a nonprofit research and educational organization devoted to transmitting intentional signals to extraterrestrial civilizations. Vakoch led METI's participation in Sónar Calling GJ 273b, which transmitted a series of interstellar messages to Luyten's Star, located 12.4 light years from Earth. Vakoch advocates ongoing transmission projects, arguing that this does not increase risks of an alien invasion as suggested by British cosmologist Stephen Hawking. He has participated in several SETI observation programs, and after sixteen years at the SETI Institute, where he was director of Interstellar Message Composition, Vakoch founded METI International. He has edited over two dozen books in SETI, astrobiology, the psychology of space exploration, ecocriticism, COVID, and transgender studies. Vakoch helped design the message included on NASA's Europa Clipper spacecraft. He is general editor of three book series in ecocriticism and in the intersection of space and society. Vakoch has appeared widely on television and radio as a commentator on SETI and astrobiology. He is an emeritus professor of clinical psychology at the California Institute of Integral Studies (CIIS).
Archaeology, Anthropology, and Interstellar Communication is a 2014 collection of essays edited by Douglas Vakoch and published by NASA. The book is focused on the role that the humanities and social sciences, in particular anthropology and archaeology, play in the search for extraterrestrial intelligence (SETI). The seventeen essays are gathered into four sections, which respectively explore the history of SETI as a field; archaeological comparisons for human-alien communication, such as the difficulties of translating ancient languages; the inferential gap between humans and aliens, and the consequences this would have for communication and trade; and the potential nature of alien intelligences.
{{cite book}}: CS1 maint: multiple names: authors list (link){{cite journal}}: Cite journal requires |journal= (help){{cite journal}}: Cite journal requires |journal= (help)Word MIR (it signifies both "peace" and "world" in Russian) was transmitted from the EPR on 19 November 1962, and words LENIN and SSSR (the Russian acronym for the Soviet Union) – on 24 November 1962, respectively were sent to the direction near the star HD131336 in the Libra constellation
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