Two researchers have revised the Drake equation, a mathematical formula for the probability of finding life or advanced civilizations in the universe. Credit: University of Rochester.
Are humans unique and alone in the vast universe? This question--summed up in the famous Drake equation--has for a half-century been one of the most intractable and uncertain in science.
But a new paper shows that the recent discoveries of exoplanets combined with a broader approach to the question makes it possible to assign a new empirically valid probability to whether any other advanced technological civilizations have ever existed.
And it shows that unless the odds of advanced life evolving on a habitable planet are astonishingly low, then human kind is not the universe’s first technological, or advanced, civilization.
The paper, published in Astrobiology, also shows for the first time just what “pessimism” or “optimism” mean when it comes to estimating the likelihood of advanced extraterrestrial life.
“The question of whether advanced civilizations exist elsewhere in the universe has always been vexed with three large uncertainties in the Drake equation,” said Adam Frank, professor of physics and astronomy at the University of Rochester and co-author of the paper. “We’ve known for a long time approximately how many stars exist. We didn’t know how many of those stars had planets that could potentially harbor life, how often life might evolve and lead to intelligent beings, and how long any civilizations might last before becoming extinct.”
“Of course, we have no idea how likely it is that an intelligent technological species will evolve on a given habitable planet,” says Frank. But using our method we can tell exactly how low that probability would have to be for us to be the ONLY civilization the Universe has produced. We call that the pessimism line. If the actual probability is greater than the pessimism line, then a technological species and civilization has likely happened before.”
Using this approach, Frank and Sullivan calculate how unlikely advanced life must be if there has never been another example among the universe’s ten billion trillion stars, or even among our own Milky Way galaxy’s hundred billion.
source for further reading: https://exoplanets.nasa.gov/news/1350/are-we-alone-in-the-universe-revisiting-the-drake-equation/
By Leonor Sierra, University of Rochester News | May 19, 2016