After searching out of 100000 galaxies for a particular signs of the presence of an advanced extraterrestrial civilization, a team of scientists using data from NASA’s WISE telescope have found no evidence of intelligent alien life.
The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, 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.
says Jason T. Wright, an astronomer and astrophysicist at the university’s Center for Exoplanets and Habitable Worlds. Wright’s team’s first paper dubbed the “Glimpsing Heat from Alien Technologies Survey” will appear in the Astrophysical Journal, on April 15, 2015.
Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy’s stars to power computers, space flight, communication, or something we can’t yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths.
This same basic physics causes your computer to radiate heat while it is turned on.
Roger Griffith, a researcher at Penn State and the lead author of the paper, searched almost the entire catalog of the WISE detections — nearly 100 million entries — for evidence of galaxies which emitting too much mid-infrared radiation. They the researchers found approximately 100,000 promising galaxies. Of 100,000 possibilities from the WISE survey, only 50 presented unusual radiation patterns. Wright reports:
We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilization.
Our results mean that, out of the 100,000 galaxies that WISE could see in sufficient detail, none of them is widely populated by an alien civilization using most of the starlight in its galaxy for its own purposes. That’s interesting because these galaxies are billions of years old, which should have been plenty of time for them to have been filled with alien civilizations, if they exist. Either they don’t exist, or they don’t yet use enough energy for us to recognize them.
Brendan Mullan, director of the Buhl Planetarium at the Carnegie Science Center in Pittsburgh, who was also a member of the G-HAT team:
This research is a significant expansion of earlier work in this area.
The only previous study of civilizations in other galaxies looked only 100 or so galaxies and No was looking for the heat emitted. This is a new way.
Finally, Wright concludes:
As we look more carefully at the light from these galaxies we should be able to push our sensitivity to alien technology down to much lower levels, and to better distinguish heat resulting from natural astronomical sources from heat produced by advanced technologies. This pilot study is just the beginning.