In the 1960s, theoretical physicist Freeman Dyson theorized that advanced alien civilizations could be detected by their infrared emissions. According to thermodynamics, no matter what power source is used, energy must be radiated away in the form of mid-infrared wavelength heat.
With this in mind, a team of scientists used data from NASA’s wise orbiting observatory to examine the mid-infrared wavelengths from 100,000 galaxies for signs of highly advanced civilizations. Although the researchers have found some interesting galaxies that require further examination they have found no definite signs of advanced civilizations to date.
Jason T. Wright, an assistant professor of astronomy and astrophysics at the Center for Exoplanets and Habitable Worlds at Penn State University originally conceived of and initiated the research.
“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,” said Wright in a statement.
The team calls its research Glimpsing Heat from Alien Technologies Survey (G-HAT) and the results of the preliminary findings have been published in the the Astrophysical Journal Supplement Series.
In addition to the search of distant galaxies for signs of life, the team also reports mysterious findings from within the Milky Way.
“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,” said Wright.
Penn State researcher, and lead author of the paper, scanned nearly 100 million entries of objects consistent with galaxies in the WISE catalog for objects emitting too much mid-infrared radiation. Then he selected the 100,000 most promising images and examined them individually.
“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,” said Wright.
Wright noted that the lack of any obvious alien filled galaxies is, in and of itself, a significant result.
“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,” said Wright.
Brendan Mullan, director of the Buhl Planetarium at the Carnegie Science Center in Pittsburgh and a member of the G-HAT team added that the only previous similar study examined only about 100 galaxies and wasn’t looking at the heat they emit.
The team also had to rule out objects with high mid-infrared emissions which have already been studied and attributed to natural sources. According to Matthew Povich and Jessica Maldonado of Cal Poly Pomona about a half dozen objects were previously unstudied and very unusual.
“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,“ said Steinn Sigurdsson, professor of astronomy and astrophysics at Penn State’s Center for Exoplanets and Habitable Worlds.
In the Milky Way, unusual objects detected include a bright nebula near the star 48 Librae and a cluster of objects which don’t show up at all using visible light telescopes.
“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,” Povich said.
The research is ongoing and more careful examinations of many of the objects will be made. The lack of clearly visible alien civilizations does not necessarily mean that they are not present. A galaxy is a big place to try to colonize and there is considerable evidence, among humans anyway, that advanced education leads to a decline in birth rates. These two factors might make it difficult for a highly advanced civilization to expand across a galaxy, or significant portion of one.
“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,” said Wright.
