The idea of the existence and the search for extraterrestrial life began in the 17 th century, when Galileo invented the microscope and there was the theory of Copernicus’ heliocentric system of the world.
Assumptions were made about the existence of lunar inhabitants, and later the Martians. Search for Extraterrestrial Intelligence is based on the idea of the origin and evolution of life on Earth.
Recently, however, it was suggested that in finding extraterrestrial life forms should not be restricted version of the Earth’s evolution, and perceptions about the similarity of extraterrestrial organisms with people who wrote Cosmos era.
Employees of the University of Colorado – a philosophy professor Carol Cleland and professor of molecular, cellular, evolutionary biology, Shelley Copley – created a “general theory of living systems.” According to this theory life that exists on our planet, is only a special case in the space within. Alien life forms may differ in their characteristics from the known forms of people.
According to Professor Cleland, if representatives of other life forms have a different molecular structure and different biochemical properties, they can not be detected using modern techniques and telescopes. Even the newest devices do not identify alien life forms with other DNA. The authors of this theory say about the need to study the biological abnormalities (eg, the existence of bacteria, extreme piles, which may exist in an environment unsuitable for life).
Scientists from the University of Carnegie made a list of planets, where there may be forms of life and you can search for extraterrestrial civilizations. It included the star, whose characteristics and age are similar to our Sun, and their systems. According to Margaret Tern ball, head of research, these are stellar worlds, in which she agreed to live. The favorites were the three stars of the constellation Canes Entice (beta CVn, a 26-year light-years from Earth, HD 10307, at a distance of 42 light-years away, and HD 211415, located 50 light-years), 18 Sco star from the constellation Scorpios, almost “twin “sun, star 51 Pegasus from the constellation Pegasus.
But, according to Cleland, do not limit the search for extraterrestrial life only in those stellar systems, which are similar to solar. As a result of recent discoveries is the assumption that habitable planets can exist in such stars as white dwarfs, red dwarfs, stars-super giants.