What are the odds that the universe is home to advanced alien civilizations? Mathematics give us the answer: “almost certainly existed at some point in cosmic history.”
Astronomer Frank Drake came up with an equation to help scientists ponder those odds back in 1961. Now, incorporating the latest data from the Kepler telescope, a pair of astronomers has come up with an interesting estimate.
Drake’s famous equation measures the odds that advanced civilizations are out there and broadcasting their presence. It comes down to (R*) the number of stars born each year that (fp) form planets that (ne) can support life. Out of those that can support life, how many (fl) actually do evolve life, and out of those, how many (fi) evolve intelligent species that (fc) are technologically advanced enough to release detectable signals into space? And then, finally, how long (L) do those civilizations survive to broadcast those signals?
Multiplying all those variables together would give a rough estimate of humanity’s chances of making contact with an alien civilization. Scientists still don’t know what numbers to plug into most of the variables, but they’re getting closer.
In the New York Times, study author Adam Frank describes the research in an article titled, “Yes, There Have Been Aliens.“
“Instead of asking how many civilizations currently exist, we asked what the probability is that ours is the only technological civilization that has ever appeared. By asking this question, we could bypass the factor about the average lifetime of a civilization.
This left us with only three unknown factors, which we combined into one “biotechnical” probability: the likelihood of the creation of life, intelligent life and technological capacity.
…What our calculation revealed is that even if this probability is assumed to be extremely low, the odds that we are not the first technological civilization are actually high. Specifically, unless the probability for evolving a civilization on a habitable-zone planet is less than one in 10 billion trillion, then we are not the first.”
Scientists have estimated that there is only a one in 10 billion chance per planet that an advanced communicative species would evolve. But even with those slim odds, more than a trillion advanced alien civilizations could have evolved over the history of the universe.
While the calculations don’t say much about whether advanced alien civilizations currently exist, Frank writes, they “almost certainly existed at some point in cosmic history.”