And even with this possibility may exist in a galaxy millions of advanced civilizations.
"Mission« Kepler »has shown us that the Milky Way is about a trillion planets in their galaxy than stars," said physicist Dan Virthaymer Berkeley, who leads the world's longest-running SETI project using the Arecibo telescope in Puerto Rico. "One day, humans may come in contact with civilizations billions of years ahead of us."
Last year, scientists selected 86 stars from a list of candidates in 1235, known at that time. Stars were selected from 5-6 planets, which presumably had conditions similar to earth, including temperature and the possible existence of liquid water. Telescope, sponsored by the National Science Foundation, spent 12 hours collecting five-minute recording of radio emission from each star in the range of 1.1-1.9 GHz, which correspond to the range in the world between cell phones and television. Then analyzed the data for high-intensity signal in a narrow band (5 Hz), which can only be generated artificially — presumably members of intelligent life.
Most of the stars are more than a thousand light-years, so that could be detect only signals deliberately aimed in our direction. Scientists say that in the future, more sensitive telescopes can detect much weaker radiation, possibly accidental leakage of radiation, such as those that take place in our civilization.
In the future physics program at Berkeley SETI plans to monitor the star with two transit planets in the hope overheard signals interplanetary communication. Because these signals are narrow, they will be much more powerful and more easily seen from the Earth.
The team also plans to conduct more observations with a telescope «Green Bank», focusing on multiplanetnyh systems, in which two of the planets have conditions similar to earth, potentially also may allow to detect signals of interplanetary communication.
"This project illustrates the power of our new-found understanding of exoplanets in programs SETI», says Virthaymer. "We no longer have to wonder whether we have chosen for your search for planets like the Earth, so we can know for sure."