By 2040 or so, astronomers will have scanned enough star systems to detect alien-produced electromagnetic signals, according to Seth Shostak of the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California.
"I think we'll find ET within two dozen years using these sorts of experiments," Shostak said during a discussion at the 2014 NASA Innovative Advanced Concepts symposium at Stanford University last week.
"Instead of looking at a few thousand star systems, which is the tally so far, we will have looked at maybe a million star systems 24 years from now. A million might be the right number to find something," Shostak said.
Part of Shostak's prediction is based on progress made by NASA's planet-hunting Kepler space telescope, which has turned up evidence that the Milky Way galaxy is packed with worlds capable of supporting life as we know it, 'SPACE.com' reported.
Shostak believes that that one in five stars has at least one planet where life might spring up.
"That's a fantastically large percentage. That means in our galaxy, there's on the order of tens of billions of Earth-like worlds," he said.
At least some of these worlds host intelligent aliens - beings that have developed the capability to send electromagnetic signals out into the cosmos, as human civilisation does every second of every day, Shostak said.