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“We really do know that pretty much every star in the sky hosts at least one planet,” says astronomer Adam Frank.

The possibility that we earthlings are not truly alone in the universe has gained some added credibility, thanks to a new study that coincides with NASA’s recent planetary discoveries. The research, published in the journal Astrobiology last week, suggests that more planets in the Milky Way galaxy may harbor advanced civilizations than we previously imagined.

Study co-authors Adam Frank and Woodruff Sullivan looked at recent discoveries of potentially habitable exoplanets and considered the odds of whether sophisticated civilizations existed on them in the past or present.

“What we showed was the ‘floor’ on the probability for a civilization to form on any randomly chosen planet,” Frank, a University of Rochester physics and astronomy professor, told The Huffington Post in an email. “If we are the only civilization in cosmic history, then that what we calculated is the actual probability nature has set. But if the actual probability is higher than that floor, then civilizations have happened before.”

Frank says the potential number of planets orbiting their parent stars within a habitable distance is staggering.

“Even if you are pretty pessimistic and think that you’d have to search through 100 billion (habitable zone) planets before you found one where a civilization developed, then there have still been a trillion civilizations over cosmic history!” Frank wrote. “When I think about that, my mind reels — even if there is just a one in a 100 billion chance of evolution creating exo-civilizations, the universe still has made so many of them that we are swamped by histories other than our own.”

While the Drake equation calculates the number of advanced alien civilizations that could exist in the Milky Way galaxy, Frank and Sullivan’s equation expands the question to calculate the number of advanced civilizations that have existed in our galaxy throughout the whole history of the universe.

In their Astrobiology paper, Frank and Sullivan write:

“Recent advances in exoplanet studies provide strong constraints on all astrophysical terms in the Drake equation. We set a firm lower bound on the probability that one or more technological species have evolved anywhere and at any time in the history of the observable universe.”

The two scientists address what they refer to as “the cosmic frequency of technological species.”

“The universe is more than 13 billion years old,” Sullivan, of the astronomy department and astrobiology program at the University of Washington, said in a statement. “That means that even if there have been 1,000 civilizations in our own galaxy, if they live only as long as we have been around — roughly 10,000 years — then all of them are likely already extinct. And others won’t evolve until we are long gone."

“For us to have much chance in finding another ‘contemporary’ active technological civilization, on average they must last much longer than our present lifetime,” Sullivan said.

“Ten thousand years from now, no one will remember anything about our era except it was when we discovered this single profound fact: We live in a cosmos of planets.”