“In the original formulation, this factor was thought to be nearly 1, or 100% — that is, evolution on all planets with life would march forward and, with enough time, turn into an intelligent civilization. Our perspective is: That’s not true,” Professor Stern said.
The researchers propose a revision to the Drake equation that defines fi as the product of two terms:
foc: the fraction of habitable exoplanets with significant continents and oceans;
and fpt: the fraction of planets that have had long-lasting plate tectonics.
Based on the team’s analysis, the fraction of the exoplanets with optimal water volume is likely very small.
The authors estimate the value of foc ranges between 0.0002 and 0.01.
Similarly, they conclude that plate tectonics lasting more than 500 million years is also highly unusual, leading to an estimate of fpt at less than 0.17.
“When we multiply these factors together, we get a refined estimate of fi that is very small, between 0.003% and 0.2%, instead of 100%,” Professor Stern said.
“This explains the extreme rareness of favorable planetary conditions for the development of intelligent life in our Galaxy and resolves the Fermi paradox.”
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