How did complex life appear and develop on Earth and what does this mean for the search for life beyond Earth? This is what was published in a recent study Nature hopes to turn to how a couple of researchers have investigated how plate tectonics, oceans and continents are responsible for the emergence and evolution of complex life on our planet and how this can solve the Fermi paradox in an attempt to improve the Drake equation as to why we have not found life in the universe and the parameters for finding life, respectively. This research has the potential to help researchers better understand the criteria for finding life beyond Earth, particularly as it relates to geological processes that manifest on Earth.
here The universe today discusses this study with Dr. Taras Geria, who is Professor of Earth Sciences at the Swiss Federal Institute of Technology (ETH-Zurich) and a co-author of the study, regarding the motivation for the study, the significant results, the follow-up studies, what it means for the Drake equation, and the study’s implications for search for life beyond the Earth. So what was the motivation behind this study?
Dr. Geria tells The universe today, “This was motivated by Fermi’s paradox (‘Where’s everybody?’) which indicates that the Drake equation generally predicts that there are between 1,000 and 100,000,000 actively communicating civilizations in our galaxy, which is an overly optimistic estimate. We tried to figure out what might need to be corrected in this equation to make the prediction using the Drake equation more realistic.”
For the study, the duo of researchers compared two types of planetary tectonic processes: a single lid (also called a stagnant lid) and plate tectonics. A single lid refers to a planetary body that does not exhibit plate tectonics and cannot be broken into separate plates that exhibit movement by sliding toward each other (convergent), sliding past each other (transform), or sliding apart from each other (divergent). This lack of tectonic activity is often explained by the fact that the lid of a planetary body is too strong and dense to break apart. Ultimately, the researchers estimated that 75 percent of planetary bodies that exhibit active convection in their interiors do not exhibit plate tectonics and have single lid tectonics, with Earth being the only planet to exhibit plate tectonics. Therefore, they concluded that single lid tectonics “is likely to dominate the tectonic styles of active silicate bodies in our galaxy,” according to the study.
In addition, researchers have investigated how planetary continents and oceans facilitate the evolution of intelligent life and technological civilizations. They noted the importance of life first developing in the oceans because they were protected from harmful space weather by the single-celled life that flourished in the oceans during the first few billion years of Earth’s history. However, the researchers also point out that the dry land provided many advantages for the evolution of intelligent life, including adaptations to different conditions, such as eyes and new senses, which facilitated the rapid development of animals for hunting among other biological assets that gave rise to life. adapt to different land conditions around the planet.
Ultimately, the researchers concluded that land contributed to the development of intelligent life across the planet, including abstract thinking, technology, and science. So what were the most significant findings of this study and what follow-up studies are currently in development or planned?
Dr. Geria tells The universe today, “These very special conditions (>500 million years of coexistence of continents, oceans and plate tectonics) are necessary on a planet with primitive life to develop intelligent technological communicative life. This condition is very rarely fulfilled: only <0.003-0.2% of planets with any life can satisfy this condition.”
Dr. Geria continues: “We plan to study the evolution of water in the interior of the planet to understand how the stability of the surface ocean volume (meaning the stability of the coexistence of oceans and continents) can be maintained over billions of years (as on Earth). We also plan to investigate the survival time of technological civilizations based on models of societal collapse. We also started a project on the evolution of oxygen saturation of the planet’s interior and atmosphere to understand how oxygen-rich atmospheres (necessary, in particular, for the development of technological civilizations) can form on planets with oceans, continents and plate tectonics. Progress in these three areas is very important, but will largely depend on the availability of research funding.”
As noted, this study was motivated by an attempt to improve upon the Drake equation, which offers a multivariate equation that attempts to estimate the number of Active Communicating Civilizations (ACCs) that exist in the Milky Way Galaxy. In 1961, Dr. Frank Drake was asked to postulate several concepts that he urged the scientific community to consider when discussing how and why we don’t hear from ACCs, and went as follows:
N = R* xfold xnd xfl xfi xfc x L
N = number of technological civilizations in the Milky Way galaxy that can potentially communicate with other worlds
R* = average star formation rate in the Milky Way galaxy
eold = fraction of these stars with planets
nd = average number of potentially life-supporting planets per star with planets
el = fraction of planets capable of supporting and developing life at some point in its history
ei = fraction of planets on which life develops and evolves into intelligent life
ec = fraction of civilizations developing technology capable of sending detection signals into space
L = the amount of time that technological civilizations send signals into space
According to the study, the Drake equation estimates the number of ACCs in a wide range of 200 to 50,000,000. As part of the study, the researchers proposed adding two additional variables to the Drake equation based on their findings that plate tectonics, oceans, and continents played a vital role in the development and evolution of complex life on Earth, namely:
eacc = fraction of habitable exoplanets that have discernible continents and oceans
eFri = fraction of habitable exoplanets that have prominent continents and oceans that also exhibit plate tectonics that have been active for at least 500 million years
Using these two new variables, the study provided new estimates for fi (chances of planets developing life and evolving into intelligent life). So what is the significance of adding two new variables to the Drake equation?
Dr. Geria tells The universe today“This allowed us to redefine and more accurately estimate the key term in the Drake equation, fi – the probability that intelligent technological communicative life will develop on a planet with primitive life. Initially fi was (incorrectly) rated as very high (100%). Our estimate is many orders of magnitude lower (<0.003-0.2%), which probably explains why we are not contacted by other civilizations.”
Also, when introducing these two new variables into the entire Drake equation, the study estimates a much lower number of ACCs at <0.006 per 100,000, in stark contrast to the original Drake equation estimates of 200 to 50,000,000. So what implications could this study have? to find life beyond Earth?
Dr. Geria tells The universe today“This has three main implications: (1) we should not have much hope of being contacted (the probability of this being very low, in part because the lifespan of technological civilizations may be shorter than previously expected), (2) we should use remote sounding to look for planets with oceans, continents, and plate tectonics (COPT planets) in our galaxy based on their likely clear (CO2-poor) atmospheres and signatures of surface reflectivity (due to the presence of oceans and continents), (3 ) we should care about our own planet and civilization, both extremely rare and must be preserved.”
This research comes as the search for life beyond Earth continues to gain momentum: NASA has confirmed the existence of 5,630 exoplanets as of this writing, with nearly 1,700 classified as super-Earths and 200 as rocky exoplanets. Despite these incredible numbers, especially since exoplanets began to be discovered in the 1990s, no type of signal from an extraterrestrial technological civilization, referred to in this study as ASS, has yet been detected to humanity.
Perhaps the closest we got to receiving a signal from space was the Wow! the signal, which was a 72-second radio burst, was received by Ohio State University’s Big Ear radio telescope on August 15, 1977. However, since then, this signal has not been received, nor has there been a complete absence of signals. With this research, scientists may be able to use the two new variables added to the Drake equation to narrow down the search for intelligent life beyond Earth.
Dr. Geria concludes with a story The universe today, “This research is part of a new emerging science – biogeodynamics, which we are trying to support and develop. Biogeodynamics aims to understand and quantify the relationship between the long-term evolution of the planet’s interior, surface, atmosphere, and life.”
How will these two new variables added to the Drake equation help scientists find life beyond Earth in the coming years and decades? Only time will tell, and that’s why we are science!
As always, keep learning and keep looking!