In May, researchers published a study that provided a new theory to the origin of plate tectonics. It concluded that the collision between Gaia and Theia, which created modern Earth as we know it, is a critical factor in why we have dynamic plate tectonics today. A new study conducted by the University of Texas at Dallas and the Swiss Federal Institute of Technology in Zurich goes further. It states plate tectonics is the reason we haven’t encountered extraterrestrial life.
The study. The paper, published in Nature, examines the lack of “active and communicative civilizations” and suggests a meaningful change in the Drake equation, the formula devised by astronomer Frank Drake in 1961 that astronomers use to estimate the number of intelligent civilizations in our galaxy capable of communicating with humans. Although it provides no answer, and we’ve found no evidence to support it, this equation consists of asking a question: How many alien societies exist, and are they detectable? In this regard, the Fermi paradox describes the apparent contradiction between the fact that we haven’t yet found evidence of extraterrestrial life despite the high probability that other intelligent civilizations exist.
What do geophysicists propose now? Drake’s formula has a part that refers to the fraction of planets with life where intelligent life arises. The new research suggests that experts should consider large oceans, continents, and plate tectonics.
Velocity vectors of tectonic plates obtained by precise GPS positioning.
The theory of plate tectonics. This formulation is a framework of study that explains the structure and movement of Earth’s lithosphere. It proposes that several large, rigid plates called tectonic plates make up the lithosphere—the outermost, rigid layer of the Earth, including the upper mantle and crust. These plates slowly move over the asthenosphere, a softer, more moldeable layer of the Earth’s upper mantle. These movements create mountains, volcanoes, and oceans.
The details of this theory are much more complex. Still, to give you an idea, its formulation has revolutionized geology by providing a coherent framework for understanding the Earth’s dynamics and changes over geologic time.
Plates to start it all. Geoscientist Robert Stern, a professor at the University of Texas at Dallas, said that plate tectonics sets the evolutionary machine in motion, “and we think we understand why.” In this regard, the lead researcher of the new study recalls that life has existed on Earth for about four billion years, “but complex organisms like animals didn’t appear until about 600 million years ago, which is not long after the modern episode of plate tectonics began.”
Lithospheric structures involved in plate tectonics.
Stern emphasizes the theory of tectonics: As plates move, they create new landforms, forming weather systems and climates. Weathering brings nutrients to the oceans, while the birth and death of habitats forces species to evolve and adapt.
Fermi paradox. When we talk about the Fermi paradox, we refer to the apparent contradiction between the high probability of the existence of extraterrestrial life in the universe and the lack of evidence or contact with such civilizations. The physicist and Nobel laureate Enrico Fermi formulated this paradox when he asked, “Where is everybody?” during an informal conversation in 1950. The paradox highlights the discrepancy between the expectation that the universe should be teeming with life and the reality that we’ve found no sign of it.
The new study suggests that the type of tectonic activity of planets that affects biological evolution has solved the problem of the Fermi paradox. This argument claims that a shift from simple to modern plate tectonics occurred between 1 billion and 541 billion years ago, accelerating the evolution of complex life on Earth.
Conceptual design of NASA’s Earth-like “planet finders.”
Two more factors. Experts constantly suggest that both continents and oceans are necessary for extraterrestrial life. Early life needs water, but advanced life that technology can create needs land. To explain the Fermi paradox, the paper suggests adding two new factors to the Drake equation: the fraction of habitable planets with significant continents and oceans and those that have had plate tectonics for at least 500 million years.
The key? Because the two factors are so small, planets rarely have the right conditions for intelligent civilizations. The study suggests that this rarity may explain why we haven’t found evidence of them.
In addition, part of the Drake equation refers to the fraction of planets with life where intelligent life emerges. The new research suggests that experts should consider the need for large oceans, continents, and plate tectonics at least 500 million years old.
Figures engraved on the Pioneer 10 spacecraft plaque informing a possible extraterrestrial civilization of the presence of human life on Earth.
The conclusion. The study concludes that Earth’s plate tectonics and the existence of continents and oceans are necessary for advanced life.
Adding these factors to the Drake equation (planets with significant continents, oceans, and plate tectonics millions of years old), the authors argue that the probability of finding such planets is extremely low (less than 0.00003 to 0.002). Therefore, this scarcity of suitable conditions would explain the lack of evidence for active, communicative civilizations that address the Fermi paradox.
Finally, the paper concludes that Earth is the only planet in the solar system with plate tectonics: “It is much more common for planets to have an outer solid shell that is not fragmented, which is known as single-lid tectonics. But plate tectonics is much more effective than single-lid tectonics for driving the emergence of advanced life-forms.”
This article was written by Miguel Jorge and originally published in Spanish on Xataka.
Imagen | Mya Jamila | Mahdi Abdulrazak | NASA | USGov
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