In 1960, Frank Drake, an astronomer at Cornell University, laid the foundation for an experiment called SETI (Search for Extra-Terrestrial Intelligence), in which scientists around the world are looking for signals from extraterrestrial civilizations. Initially, Drake began to monitor radio signals from the stars Tau Keith and Epsilon Eridan, which were considered the most likely candidates for the presence of planets of earth type. Within two months, the antennas were installed in the direction of two adjacent stars, its receiver was tuned to a frequency of 1420 MHz. No signals of extraterrestrial origin had yet been detected. Drake also created his famous Drake equation formula to calculate the number of civilizations in the galaxy with which contact is possible.
Around the same time, physicists Cocconi and Morrison published an article in Nature magazine, where they noted the great potential in the use of radio waves in the search for extraterrestrial civilizations.
Physicist Enrico Fermi formulated a thesis (Fermi paradox) in response to a rather high estimate of the chances of interplanetary contact according to the Drake equation: if there are so many alien civilizations, why does mankind not observe any trace of these civilizations? This paradox is explained by the hypothesis of the uniqueness of the Earth, which is proposed by some physicists and astronomers. They claim that all life forms should be built on the basis of carbon like ours.
Frank Drake is currently the director of the Center for Universe Life Research, looking for extraterrestrial optical signals and developing radio telescope designs for SETI. In particular, his proposals are used in the design of Allen's Composite Radio Telescope (named after Paul Allen, founder of Microsoft) in California, one of the most famous projects in the search for extraterrestrial intelligence.
The first 42 telescope antennas were launched in 2007, and a total of 350 antennas are planned to be built for the search for extraterrestrial civilizations.
Searching for other civilizations
In the USSR in the early 1960s, there was also an interest in the search for extraterrestrial intelligent life forms. The Sternberg State Astronomical Institute brought together a group of enthusiasts to search for signals from space. This idea was supported by outstanding physicists. At that time, the Americans did not enter the name of their SETI project, so the Russian program had an interesting name "Project Au". A lot has been done by Russian specialists during this time: apart from active discussion of the problem, distant space depths were mastered. And at the moment the technique allows to view the Universe in the whole range of radio emissions, photographing the radiation spectra of distant stars.
The first radio message to space was sent in 1962 by the SETIB project, which contained three words "World, Lenin, USSR". In 1774 the Americans sent their signal from the radio telescope to Arecibo. Three subsequent messages were sent from the radar telescope in Evpatoria in 1999, 2001 and 2003 by the Institute of Radio Engineering and Electronics. They contained digital and analog information (lyrics and music) and headed for several solar-type stars.
These messages are expected to be received for at least 30 years and to go back as long as possible. Some experts believe that these are all attempts to find a civilization like ours. But perhaps there are other civilizations that are millions of years older than ours and that communicate with each other through "dark matter". There is an assumption that the presence of this very matter explains the "silence" of the universe. The Physical Institute of the Academy of Sciences has compiled a list of one hundred stellar systems closest to the Earth, analyzing the entire array of stars discovered by mankind. Of these, about 58 can be SETI objects.
In 2006, the U.S. Planetary Community in the framework of the SETI project presented a new powerful telescope for the search for extraterrestrial civilizations. By that time, many years of experience in radio research had been accumulated and it was decided to focus on finding and recording light signals rather than radio signals from space. Visible light can easily travel through outer space, and a focused bright laser-like beam can be several times brighter than the Sun, allowing it to be detected from space distances. Unlike radio waves, light signals are unidirectional, making it possible to set their source. Extraterrestrial civilizations, according to the American community, can use light signals to communicate with the Earth with the same success as radio signals.
The telescope was installed at the Massachusetts State Observatory and cost more than 400 thousand dollars, which is much less than the cost of a conventional research telescope. Interest in the SETI project has grown, and there is a lot of hope for it.
The SETI distributed computing project SETI@home started in 1995 as part of the SETI project. It involves volunteers who have to provide free resources to their home computers to process signals collected from space.
The SETICurrent project, having registered on the project's website, can even improve the code of the programs used to decrypt and process the digital signal from Allen's telescopes. Programmers with programming skills can study the processed data in a collective search for possible signals of artificial origin.
At the annual conference in California, which was held in 2010, the prize for the dissemination of worthy ideas in this field was awarded. It was awarded to astronomer Jill Tarter and she wished that all earthlings would have an opportunity to become active participants in the search for extraterrestrial civilizations. In the same year, in honor of the 50th anniversary of the project to find a reasonable life in the universe, the British people had the opportunity to send messages to extraterrestrial civilizations. All citizens over 16 years of age, who wished to send this message, filled out a form on the site of Penguin publishing house with a length of no more than 40 words. The first few thousand messages were sent to space with the help of a radio telescope, and the authors of the most interesting messages received as a gift the book of the theoretical physicist Paul Davis "Sinister Silence: Are We Lonely in the Universe? The announcements were of different content, including joking ones, for example, "An attractive form of life, reflecting on whether it is lonely in the universe, wants to get acquainted with other forms of life for serious relationships. You need to have a good sense of humor.