No signs of advanced alien life in 93 neighboring galaxies – study
The study examined the most promising galaxies, which were those emitting the largest amounts of heat or mid-infrared emission. The galaxies had been identified earlier in the year by a team from Penn State University.
The Netherlands-based team, led by the National Institute for Radio Astronomy (ASTRON), used advanced telescopes to identify the sources of the excessive radiation in hopes of determining if they exhibited signs of advanced alien civilization life.
The astronomers eliminated galactic stars, diffuse nebular emissions, and other stellar artifacts from their potential targets, but found that the emissions from the majority of the observed galaxies could be explained by astrophysical processes, such as dust being generated and heated by a massive star formation.
“The original research at Penn State has already told us that such systems are very rare, but the new analysis suggests that this is probably an understatement, and that advanced Kardashev Type III civilizations basically don’t exist in the local universe,” Michael Garrett, author and professor at the University of Leiden and scientific director of ASTRON, the Netherlands Institute for Radio Astronomy, said in a statement.
“In my view…an alien invasion doesn’t seem at all likely,” added Garrett joking.
The Kardashev scale, invented by Russian astronomer Nikolai Kardeshev in 1964, is a hypothetical method that can be employed to measure a civilization’s level of technological advancement based on the amount of energy it is able to utilize. According to this method of classification, a Type I civilization uses all the available resources on its home planet, Type II civilizations harness all of the energy available from their stars, and Type III from their galaxies.
Garrett’s technique, which measures infrared emissions via telescope, might also help identify less advanced Kardashev Type II civilizations. This is what Garrett’s team intends to study next.
“It’s a bit worrying that Type III civilizations don’t seem to exist,” Garrett told Science.com. “It’s not what we would predict from the physical laws that explain so well the rest of the physical universe.”
He suggested that such civilizations could be far more energy efficient, producing such little waste heat as to be beyond scientists’ current understanding of physics.
“What’s important is to keep on searching for the signatures of extraterrestrial intelligence until we fully understand just what is going on,” Garrett said.
The research was published September 15 in the journal Astronomy & Astrophysics.