Robert Hansen Gray | |
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 Gray in 2012. | |
| Born | March 7, 1948 |
| Died | December 6, 2021 (aged 73) |
| Nationality | American |
| Alma mater | Shimer College University of Illinois at Chicago |
| Occupation(s) | Data analyst, writer, astronomer |
| Years active | 1982-2021 |
| Spouse | Sharon A. Hoogstraten |
Robert Hansen Gray (March 7, 1948 - December 6, 2021) was an American data analyst, author, and astronomer, and author of The Elusive Wow: Searching for Extraterrestrial Intelligence.
Gray attended Shimer College, a Great Books school then located in Mount Carroll, Illinois, where he received a bachelor's degree in 1970. [2] He went on to obtain a master's in urban planning and policy analysis from the University of Illinois at Chicago in 1980. [3]
In 1984, Gray founded the company Gray Data in Chicago, which provided data analysis research services and published reference cards for microcomputer software. [4] [5] He continued to work as a data analyst through his company Gray Consulting. [6]
Gray is best known for his work as an independent SETI researcher. [7] The Atlantic called Gray "the 'Wow!' signal's most devoted seeker and chronicler, having traveled to the very ends of the earth in search of it." [8]
The Wow! signal was detected by the Ohio State University Radio Observatory (also known as Big Ear) on August 15, 1977. The signal was so pronounced in the data, and so similar to a radio signal rather than a natural source, that SETI scientist Jerry R. Ehman circled it on the computer printout in red ink and wrote "Wow!" next to it. [9] After hearing about the Wow! signal a few years after its detection, Gray contacted the Ohio team, visited Big Ear, and spoke with Ehman, Robert S. Dixon (director of the SETI project) and John D. Kraus (the telescope's designer). [6]
In 1980, Gray began scanning the skies from his backyard in Chicago, using a 12-foot commercial telecommunications dish. [6] [10] [11] [12] He operated his small SETI radio observatory regularly beginning in 1983 and for the next 15 years, but did not find a trace of the Wow! signal. [6] In 1987 and 1989 he led searches for the signal using the Harvard/Smithsonian META radio telescope at the Oak Ridge Observatory in Harvard, Massachusetts. [13] In September 1995 and again in May 1996, Gray and Kevin B. Marvel reported searches for the signal using the Very Large Array (VLA) radio telescope in New Mexico [14] [15] (which is an array of 27 dishes simulating a single dish with a diameter of up to 22 miles), [6] becoming the first amateur astronomer to use the VLA, and the first individual to use it to search for extraterrestrial signals. [8] The VLA was, until the end of the twentieth century, the most powerful radio telescope ever built. [8] In 1998, he and University of Tasmania professor Simon Ellingsen conducted searches using the 26-meter dish at the Mount Pleasant Radio Observatory in Hobart, Tasmania. [7] [8] [13] [14] Gray and Ellingsen made six 14-hour observations where the Big Ear was pointing when it found the Wow! signal, searching for intermittent and possibly periodic signals, rather than a constant signal. [7] [9] No signals resembling the Wow! were detected. [7]
Gray and Marvel published a 2001 paper in The Astrophysical Journal detailing his use of the VLA in search of the signal. [8] Gray and Ellingsen published "A Search for Periodic Emissions at the Wow Locale" in the October 2002 issue of The Astrophysical Journal, reporting on searches for the Wow! signal. [16] [17] In 2011, Gray published the book The Elusive Wow: Searching for Extraterrestrial Intelligence, summarizing what is known about the Wow! signal, covering his own search for the signal, and offering an overview of the search for extraterrestrial intelligence. [8] [13] [18]
In 2016, Gray published an article in Scientific American about the Fermi paradox, which claims that if extraterrestrials existed, we would see signs of them on Earth, because they would certainly colonize the galaxy by interstellar travel. Gray argued that the Fermi paradox, named after Nobel Prize-winning physicist Enrico Fermi, does not accurately represent Fermi's views. Gray stated that Fermi questioned the feasibility of interstellar travel, but did not say definitively whether or not he thought extraterrestrials exist. [19]
Gray lived in Chicago, Illinois, [7] with his wife, photographer Sharon A. Hoogstraten. [20] He died on December 6, 2021 from complications from lung cancer in Chicago. [21]
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 refers to hypothetical intelligent extraterrestrial life. No such life has ever been proven to exist in the Solar System except for humans on Earth, and its existence on other star systems is still speculative. 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".
In astrobiology, Uniformity of Motive is an essential assumption of the Zoo Hypothesis explanation to Fermi’s Paradox. The Zoo Hypothesis states that alien civilizations refrain from contacting Earth, so as to not interfere in natural evolution and cultural development, or to minimize risk for themselves. Certain technological, political or ethical thresholds and standards could be implemented for other civilizations to pass, after which contact would be established.
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 the expected hallmarks of extraterrestrial origin.
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. The Great Filter is one possible resolution of the Fermi paradox.
The Ohio State University Radio Observatory was a Kraus-type radio telescope located on the grounds of the Perkins Observatory at Ohio Wesleyan University in Delaware, Ohio from 1963 to 1998. Known as Big Ear, the observatory was part of Ohio State University's Search for Extraterrestrial Intelligence (SETI) project. The telescope was designed by John D. Kraus. Construction of the Big Ear began in 1956 and was completed in 1961, and it was finally turned on for the first time in 1963.
The Allen Telescope Array (ATA), formerly known as the One Hectare Telescope (1hT), is a radio telescope array dedicated to astronomical observations and a simultaneous search for extraterrestrial intelligence (SETI). The array is situated at the Hat Creek Radio Observatory in Shasta County, 290 miles (470 km) northeast of San Francisco, California.
The waterhole, or water hole, is an especially quiet band of the electromagnetic spectrum between 1420 and 1662 megahertz, corresponding to wavelengths of 21 and 18 centimeters, respectively. It is a popular observing frequency used by radio telescopes in radio astronomy.
SERENDIP is a Search for Extra-Terrestrial Intelligence (SETI) program originated by the Berkeley SETI Research Center at the University of California, Berkeley.
Active SETI 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.
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 Listen is a project to search for intelligent extraterrestrial communications in the Universe. With $100 million in funding and thousands of hours of dedicated telescope time on state-of-the-art facilities, it is the most comprehensive search for alien communications to date. The project began in January 2016, and is expected to continue for 10 years. It is a component of Yuri Milner's Breakthrough Initiatives program. The science program for Breakthrough Listen is based at Berkeley SETI Research Center, located in the Astronomy Department at the University of California, Berkeley.
The Berkeley SETI Research Center (BSRC) conducts experiments searching for optical and electromagnetic transmissions from intelligent extraterrestrial civilizations. The center is based at the University of California, Berkeley.
Simon Ellingsen is a professor in physics and Dean of the School of Natural Sciences at the University of Tasmania.
Alberto Caballero is a Spanish astronomer and science communicator. He is known for having identified a Sun-like star in the sky region where the Wow! signal came from as one of the possible sources of the radio signal. Caballero is also known for founding and coordinating the Habitable Exoplanet Hunting Project, an international effort consisting of more than 30 observatories searching for nearby potentially habitable exoplanets. Data is collected 24/7 from specific stars by observatories located both in the Northern and Southern hemispheres, and an initial list of exoplanet candidates was made public in 2020.
The following outline is provided as an overview of and topical guide to extraterrestrial life:
Gray.
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