Within the range of uncertainties in the relevant astronomical and biological parameters, the Drake equations typically predict that many exoplanets should exist (
Stern and Geriya argue that the lack of evidence for active, communicative civilizations reflects the rare absence of long-lived plate tectonics, continents, or oceans on exoplanets that could host primitive life. Image credit: Sci.News.
In 1961, American astrophysicist and astrobiologist Dr. Frank Drake devised an equation that multiplied several factors to estimate the number of intelligent civilizations in the galaxy that could make their presence known to humanity.
N = R * fp * noe * debtl * debtI * debtc * no
N: The number of civilizations in the Milky Way that have detectable electromagnetic radiation (such as radio waves).
R: The number of stars formed per year.
debtp: The percentage of stars with planetary systems.
yeahe: The number of planets per solar system that have environments suitable for life.
debtl: The percentage of planets suitable for life to actually emerge.
debtI: The percentage of planets that are habitable and on which intelligent life forms emerge.
debtc: The percentage of civilizations that have developed technology that can detect evidence of their own existence.
L: The average time (in years) for such a civilization to produce such a manifestation.
Assigning values ​​to the seven variables is an educated guessing game that has led to the prediction that such civilizations must have existed widely. But if that's true, why is there no conclusive evidence of their existence?
This contradiction is known as the Fermi Paradox, named after the Italian-American nuclear physicist and Nobel Prize winner Dr. Enrico Fermi, who posed the question privately to his colleagues.
“Life on Earth has been around four billion years old, but complex organisms like animals didn't appear until shortly after modern plate tectonics began, around 600 million years ago,” Prof Stern said.
“Plate tectonics really is what kicks off the evolutionary machine, and I think we understand why.”
In their paper, Professors Stern and Geria propose improving one of the factors, f, of the Drake equation.Ithe percentage of habitable planets on which intelligent life arises. These planets need to have extensive oceans and continents, and we need to take into account that plate tectonics have been in place for over 500 million years.
“In the original formulation, this coefficient was thought to be close to unity, or 100%, meaning that on every planet where life exists, evolution will progress and, given enough time, turn into an intelligent civilization. Our view is that that's not true,” Prof Stern said.
The researchers propose a revision of the Drake equation that defines f.I As a product of two terms:
debtoc: The percentage of habitable exoplanets with significant continents and oceans.
and fpt: The percentage of planets that have had long-term plate tectonics.
The team's analysis suggests that the proportion of exoplanets with optimal amounts of water appears to be very small.
The authors estimate the value of f.oc The range is 0.0002 to 0.01.
Similarly, they concluded that plate tectonics lasting more than 500 million years is highly unusual.pt It is less than 0.17.
“Multiplying these factors together gives us a refined estimate of f.I “It's not 100%, it's very small, between 0.003% and 0.2%,” Prof Stern said.
“This explains why planetary conditions suitable for the development of intelligent life are extremely rare in our galaxy, resolving the Fermi Paradox.”
“Biogeochemistry assumes that the solid Earth, and in particular plate tectonics, accelerates the evolution of species,” he added.
“Studies like ours are useful because they encourage us to think broadly about bigger mysteries and provide examples of how we can apply our knowledge of the Earth system to intriguing questions about the universe.”
of paper Published in the April 2024 issue Scientific Reports.
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Stern, R.J. & Geriya, T.V. 2024. The importance of continental, oceanic, and plate tectonics in the evolution of complex life: Implications for the discovery of extraterrestrial civilizations. Scientific Reports 14, 8552; doi: 10.1038/s41598-024-54700-x
This article has been edited based on the original release from the University of Texas at Dallas.
Source: www.sci.news
