Paper Proposes New Way to Calculate Number of Alien Civilizations

"It's completely undeniable that every civilization must have a beginning and an end."

Equation Station

In a new study, scientists take on the search for extraterrestrial intelligence (SETI) community — and determine that they may have a crisis of imagination.

Speaking to Universe Today, Columbia astronomer and paper coauthor David Kipping suggested that so-called "SETI optimists" may be missing the forest for the trees as they seek answers within our Milky Way.

Known for his "Cool Worlds" vlog on YouTube, Kipping and co-writer Geraint Lewis of the University of Sydney's Insitute for Astronomy posit in their not-yet-peer-reviewed paper that one of the most famous equations for calculating the probable number of civilizations in our galaxy may well fall short.

Back in 1961, famed astronomer Frank Drake assembled the first-ever SETI meeting at West Virginia's Greenbank Observatory. It was at that inaugural meeting that he devised what is now known as the "Drake equation," intended as an exercise in imagination that outlines all the variables for detecting advanced life elsewhere in our galaxy.

The equation, which attempts to estimate how many civilizations there are in the galaxy based on numerous variables ranging from the rate of star formation to the fraction of civilizations that eventually develop broadcast technology, has become something of a punching bag — which per Kipping and Lewis' reckoning is a shame.

"It's become a bit of a sport to critique the Drake equation," Kipping told UT. "Certainly, anyone using it as a calculator should be fairly criticized, but the basic idea is not wrong. There must be some number of civilizations out there, and we could, in principle, collect relevant parameters to calculate it."

Think Bigger

With the Drake equation and others like it concerned with the exactitudes of extraterrestrial life, these astronomers are offering a radical reduction: an equation whose only variables are the birth rate and death rate of alien civilizations.

"We often get caught up arguing about which parameters to include," Kipping bemoaned. "But it's completely undeniable that every civilization must have a beginning and an end."

When doing calculations along this "birth-death" version of the Drake equation, the possibility arises that humanity simply happened to come about during a time when other extraterrestrial civilizations in our galaxy are rare or nonexistent. Even if that's true, though, there could be plenty more beyond it.

"I think my favorite way out is that our galaxy is just unusually quiet, most are busy and filled, but we are the first in the Milky Way," Kipping concluded. "This seems improbable, but perhaps being born in a busy galaxy is impossible since the habitable real estate has already been gobbled up. This suggests we should put more emphasis on extra-galactic SETI as our best shot."

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