Study: No evidence of advanced alien life in nearby galaxies

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While a sequel to the 1990s alien invasion flick “Independence Day” is in the works, moviegoers shouldn’t worry about fact following fiction anytime soon. This is according to a new report by the Netherlands Institute for Radio Astronomy, which determined that there are no signs of advanced alien life in 93 of our neighboring galaxies.

Using an earlier Penn State study led by Jason Wright, professor and report author Michael Garrett (ASTRON, University of Leiden) poured through data compiled from 100,000 galaxies with unusually extreme mid-infrared (MIR) emission detected by NASA’s Widefield Infrared Survey Explorer satellite. From there, he chose the best candidates for hosting advanced alien life based on the amounts of MIR and radiowave emissions.

The general belief among experts is that advanced type-three civilizations on the Kardashev scale (a system invented by Russian astrophysicist Nikolai Kardashev based on energy disposal levels) have extremely high–energy needs. In other words, the more a civilization advances, the more its energy requirements grow, what with its large population and machinery. The energy being emitted from these civilizations should then be detectable via infrared satellites.

Garrett determined that the MIR/heat emission was caused by space dust brought about by star formation rather than aliens.

“There is a nice correlation between the strength of MIR emission versus radio emission for galaxies,” Garrett told “It’s grounded by the fact that when you form stars in a galaxy, you get a lot of MIR emission from dust and a lot of radio from charged particles - the two things always go together. But if the MIR is being produced not by star formation but by waste heat from an advanced civilization, then we don't expect to see much radio emission.”

He concluded that almost all of the very best candidate galaxies listed by the Penn State team followed the natural MIR/radio correlation, thus the MIR emission was being produced by standard astrophysical processes seen in normal galaxies instead of extraterrestrials.

Still, alien hunters might not have to give up hope just yet. Garrett noted that there are still a few interesting galaxies out of the 100,000 sampled that don’t seem to produce as much radio emission, though he suspects it’s very likely that closer observation will show natural astrophysical explanations. That being said, he’s still planning on investigating them, as well as galaxies beyond those in our immediate neighborhood.

So what would be the next step if an alien civilization happened to be detected?

“If we thought we had evidence for that, we would train the best telescopes in the world on that source,” Garrett explained. “For example, we could do a conventional SETI (Search for Extraterrestrial Intelligence) search with radio telescopes looking for artificial signals associated with their own communication system — if they are advanced, these signals might be quite strong. It’s very easy to tell the difference between artificial radio emission and natural background emission.”

In an earlier statement, Garrett said he found the prospect that advanced extraterrestrial life didn’t exist “worrying.” A few months ago, famed physicist Stephen Hawking said that advanced aliens would likely conquer and colonize whatever planets they reached, including our own. Despite the dangers, he too championed the search for intelligent extraterrestrials.

“Maybe we only exist because they don't! “ Garrett said. “The worrying aspect is the scientific perspective — it's hard to believe that life is not fairly widespread within our own galaxy and others — so if civilizations like our own live long enough, there is nothing in physics to stop them becoming very advanced and making use of a lot of energy. But then we should see signatures of such civilizations in astronomical data, and we don't. There are many possible explanations one can

think of (all civilizations are short–lived and die out after using up the resources of their own planet) or on the other extreme we are really alone, which I can't believe.”

He also noted that while we have the technology to understand the universe we live in and produce the latest mobile phone, it’s not much use in explaining the “great silence” that we see.

“It’s a real puzzle,” he said.

The report can be found in the September 15 edition of the Journal Astronomy and Astrophysics.