A long, laborious study of a huge number of galaxies has found no clear signs of life or civilization other than our own. Researchers at Penn State University sifted through nearly 100 million data entries from NASA's Wide-field Infrared Survey Explorer satellite.
"If an entire galaxy had been colonized by an advanced spacefaring civilization," explained study co-author Jason Wright, " the energy produced by that civilization's technologies would be detectable in mid-infrared wavelengths, exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes."
The theory has been around since physicist Freeman Dyson suggested it in the 1960s, but collecting that data has only been possible more recently. The team whittled down the millions of records from WISE to around 100,000 — which then had to be inspected more or less manually, and largely by the paper's lead author, Roger Griffith.
The result? Nothing that screams "aliens," although 50 galaxies showed "unusually high" levels of near-infrared radiation and other interesting qualities — follow-up studies will have to be conducted. The current paper will be published in the April 15 issue of the Astrophysical Journal's Supplement Series.
Though no alien civilizations were found, the researchers are hardly discouraged.
"This research is a significant expansion of earlier work in this area," said team member Brendan Mullen of the Carnegie Science Center in Pittsburgh. "The only previous study of civilizations in other galaxies looked at only 100 or so galaxies, and wasn't looking for the heat they emit. This is new ground."
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