Remember last May when astronomers Adam Frank of the University of Rochester and Woody Sullivan of the University of Washington tweaked the famous Drake equation to probe just how hospitable the universe is to life?
It now appears that it is quite astronomically likely that alien civilizations have risen in parts of the universe during its rich 13.8-billion-year history.
In an editorial for the New York Times on June 10, Frank offered an intriguing argument favoring the existence of alien civilizations and said there is now plenty of information that they “almost certainly existed.”
“[G]iven what we now know about the number and orbital positions of the galaxy’s planets, the degree of pessimism required to doubt the existence, at some point in time, of an advanced extraterrestrial civilization borders on the irrational,” he wrote on the NYT.
The two scientists arrived at the conclusion through deconstructing the Drake equation, proposed by astronomer Frank Drake in 1961.
The classic formula begins with the rate of star formation in the Milky Way, multiplying that by the following:
• Fraction of those stars with planetary systems
• Average amount of habitable planets for each of the systems
• Fraction of such planets giving rise to life
• Fraction of those life-giving planets paving the way for civilizations
• Fraction of such civilizations beaming out proof of their existence
• Average time during which they are performing the beaming
There must be a way to simplify the equation, right? Thanks to data from NASA’s planet-scouring Kepler telescope, scientists were able to shift the focus of the equation and, instead of investigating how many civilizations currently exist, question the likelihood of earthly life being the one technologically advanced civilization ever existing.
This let them get a good handle on three unknown factors that they mixed into a single “biotechnical” probability: the probability of the creation of life, intelligent life and technological capacity.
What they discovered: even if the likelihood is deemed extremely low, the odds that life on Earth is not the first technological civilization are fairly high – a one in 10 billion trillion chance of humanity being alone in the universe is indeed very small.
According to Frank, previous talks of the equation have it that a one in 10 billion per planet probability was considered “highly pessimistic.” Their findings showed that even if that level of pessimism is granted, a trillion civilizations would still have emerged over the span of cosmic history.
Using the said pessimistic approach, Quartz made a calculation of alien civilizations emerging in different regions of the universe during its lifetime, and came up with a staggering 420 billion intelligent civilizations as its “pessimistic” estimate. Whether this is good or bad news, the report noted, depends on one’s view of alien life.
Frank and Sullivan did not put a number on how many alien species currently exist, saying there may be a long wait ahead for relevant data. Another important mystery, as Quartz pinpointed, is how long a technologically sound civilization lasts before it disappears.
Sullivan entertained this idea as well, pointing to some room for pessimism in the search for alien intelligence.
“For us to have much chance of success in finding another ‘contemporary’ active technological civilization, on average they must last much longer than our present lifetime,” he said.
The findings were detailed in the journal Astrobiology.
Photo: NASA Goddard Space Flight Center | Flickr