How Geology Resolves The Fermi Paradox

Given the diversity of voices that have weighed in on the possibility that other civilizations may be out there, it is surprising that few geoscientists—people who study the one planet known to host life—have weighed in on the cosmic conundrum. Physicist Enrico Fermi’s famous question, “Where is everybody?” has long lacked a geological perspective. 

That’s what Earth scientists Robert Stern and Taras Gerya offer in a recent paper published in Scientific Reports. Earlier speculations about extraterrestrial civilizations were based primarily on astronomical and technological considerations like the number of planetary systems in the galaxy and how long it might take an intelligent species to discover and begin using radio waves. That left little attention for the specific attributes of potential host planets—other than the presence or absence of water. 

Stern is a geologist at the University of Texas at Dallas who studies the evolution of the continental crust, and Gerya is a geophysicist at the Swiss Federal Institute of Technology who models Earth’s internal processes. Their conclusion may disappoint extraterrestrial enthusiasts: The likelihood that other technologically sophisticated societies exist is smaller than previously thought, because basic amenities we take for granted on Earth—continents, oceans, and plate tectonics—are cosmically rare.

[---]

Bringing a geologic perspective to the problem, Stern and Gerya propose to resolve the paradox by adding two more factors to the already unwieldy Drake equation: the fraction of habitable planets with distinct continents and oceans; and the fraction of those planets with a plate tectonic system that has operated for at least 500 million years. The values of these terms are very small, they argue, because the development of distinct landmasses and water bodies, and the tectonic habit of crustal recycling—characteristics of Earth that we take for granted—are unlikely outcomes in the evolution of rocky planets. 

With these new factors, the number of advanced civilizations in our galaxy that might communicate with us falls to … almost zero.

- More Here