100,000 galaxy search for intelligent life finds nothing compelling

100,000 galaxies have been searched by scientists for signs of super-advanced alien civilizations – they have so far found nothing compelling. However, some galaxies showed unusually high levels of mid-infrared radiation, which could be related to emissions from intelligent beings.

The research team, who used observations from NASA’s WISE (Wide-field Infrared Survey Explorer) orbiting observatory, insisted that their study in no way means there is nothing intelligent in space.

In the observable universe, scientists believe there are more than one billion galaxies, Searching through 100,000 of them represents just 0.01% of the total.


A false-color image of the mid-infrared nebula surrounding the nearby star 48 Librae. (NASA/JPL-Caltech)

They searched for extremely advanced civilizations that would have colonized a whole galaxy – meaning they would be technologically at least one thousand years ahead of us.

Our galaxy, the Milky Way, is 100,000 light years across. At a speed of 17.3 km/s, it would take NASA’s Voyager over 1,700,000,000 years to complete the distance.


Jason T. Wright, an assistant professor at the Center for Exoplanets and Habitable Worlds at Penn State University, who initiated the study, said:

“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.”

The study’s findings were published in the academic journal Astrophysical Journal (citation below).

Mysterious things discovered in the Milky Way

The researchers explained that if an advanced space-age civilization uses huge amounts of energy from its galaxy’s stars to power space travel, computers, communications, or something we cannot yet conceive, fundamental thermodynamics tells us this energy would probably 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,” said Prof. Wright.

Freeman Dyson, an eminent theoretical physicist and mathematician, suggested fifty years ago that a super-advanced alien civilization could be detected by the tell-tale evidence of their mid-infrared emissions.

No signs of aliens

The authors say their non-detection of advanced alien civilizations does not mean there is nothing out there.

Since the WISE satellite was launched in 2009, it has been possible to make sensitive measurements of this radiation emitted in deep space.

Lead author, Roger Griffith, a post-baccalaureate researcher at Penn State, carefully searched through the (almost) entire catalog of the WISE satellite’s detections, which included nearly 100 million entries. He was looking for objects consistent with galaxies emitting abnormal levels of mid-infrared radiation.

He then examined and categorized approximately 100,000 of the most promising images of galaxies.

50 galaxies had high mid-infrared radiation

Prof. Wright explained:

“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.”

The authors believe that, in any case, their non-detection of any clear evidence pointing to alien-filled galaxies is in itself an interesting scientific result.

Prof. Wright said:

“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.”

G-HAT team member, Brendan Mullan, director of the Buhl Planetarium at the Carnegie Science Center in Pittsburgh, said:

“This research is a significant expansion of earlier work in this area. 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.”

Co-author, Assistant Professor of Astronomy at Cal Poly Pomona, Matthew Povich, said:

“Once we had identified the best candidates for alien-filled galaxies, we had to determine whether they were new discoveries that needed follow-up study, or well-known objects that had a lot of mid-infrared emission for some natural reason.”

Jessica Maldonado, an undergraduate at Cal Poly Pomona, searched through the astronomical literature for the best of the celestial objects that had been detected as part of the project, to determine which were new to science and which were well known.

Prof. Povich said:

“Ms. Maldonado discovered that about a half dozen of the objects are both unstudied and really interesting looking.”

Puzzling new objects found

Co-author, Steinn Sigurdsson, professor of astronomy and astrophysics at Penn State’s Center for Exoplanets and Habitable Worlds, explained:

“When you’re looking for extreme phenomena with the newest, most sensitive technology, you expect to discover the unexpected, even if it’s not what you were looking for. Sure enough, Roger and Jessica did find some puzzling new objects.”

“They are almost certainly natural astronomical phenomena, but we need to study them more carefully before we can say for sure exactly what’s going on.”

In our own galaxy, the scientists discovered a bright nebula around the nearby star 48 Librae. They also found a cluster of objects in a previously-assumed ‘black’ part of the sky, which telescopes that detect only visible light would never have spotted.

Regarding the cluster and nebula, Prof. Povich said:

“This cluster is probably a group of very young stars forming inside a previously undiscovered molecular cloud, and the 48 Librae nebula apparently is due to a huge cloud of dust around the star, but both deserve much more careful study.”

Prof. Wright said:

“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.”

The study was partly funded by the John Templeton Foundation and a grant from New Frontiers in Astronomy and Cosmology.

Citation: “The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. III. The Reddest Extended Sources in WISE,” Roger L. Griffith, Jason T. Wright, Jessica Maldonado, Matthew S. Povich, Steinn Sigurđsson and Brendan Mullan. The Astrophysical Journal. Published 15 April, 2015. DOI: 10.1088/0067-0049/217/2/25.