Intelligent civilizations rarer than one in a million
"Scientists at UC Berkeley have now used the Green Bank Telescope in West Virginia to look for intelligent radio signals from planets around 86 of these stars. While discovering no telltale signs of life, the researchers calculate that fewer than one in a million stars in the Milky Way Galaxy have planetary civilizations advanced enough to transmit beacons we could detect.
“We didn’t find ET, but we were able to use this statistical sample to, for the first time, put rather explicit limits on the presence of intelligent civilizations transmitting in the radio band where we searched,” said Andrew Siemion, who recently received his Ph.D. in astronomy from UC Berkeley."
Complete article can be found here.