How did complex life arise and evolve on Earth and what does this mean for the search for life beyond Earth? This is what a recent study published in Nature hopes to address the question of how two researchers studied how plate tectonics, oceans and continents are responsible for the emergence and evolution of complex life on our planet and how this could resolve the Fermi Paradox while attempting to improve the Drake equation regarding why we haven’t found life in the universe and the parameters for finding life, respectively. This study could potentially help researchers better understand the criteria for to find life beyond Earth, particularly as it relates to geological processes observed on Earth.
Here, The universe today discusses this study with Dr. Taras Gerya, Professor of Earth Sciences at the Swiss Federal Institute of Technology Zurich (ETH-Zurich) and co-author of the study, regarding the motivation behind the study, the significant results and follow-up studies, what this means for the Drake Equation, and the study’s implications for finding life beyond Earth. So what was the motivation behind this study?
Dr. The Journey Tells The universe today“This was motivated by the Fermi paradox (“Where is everyone?”), emphasizing that the Drake equation generally predicts that there are between 1,000 and 100,000,000 actively communicating civilizations in our galaxy, which which is an overly optimistic estimate. We tried to determine what might need to be corrected in this equation to make the prediction with the Drake equation more realistic.
For the study, the research duo compared two types of planetary tectonic processes: single lid (also called stagnant lid) and plate tectonics. Single lid refers to a planetary body that does not exhibit plate tectonics and cannot be divided into separate plates that exhibit motion by sliding toward each other (convergent), sliding past each other (transformation ) or moving away from each other (divergent). This lack of plate tectonic activity is often attributed to the fact that the lid of a planetary body is too strong and too dense to be broken. Ultimately, researchers estimated that 75% of planetary bodies that exhibit active convection within their interiors do not exhibit plate tectonics and possess 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.
Additionally, researchers have studied how planetary continents and oceans contribute to the evolution of intelligent life and technological civilizations. They highlighted the importance of the evolution of life in the oceans because they are protected from harmful space weather, with single-celled life having thrived in the oceans for the first billion years of the world’s history. Earth. However, the researchers also point out that drylands offer myriad benefits for the evolution of intelligent life, including adaptations to diverse terrains, such as eyes and new senses, which have contributed to the evolution of animals towards speed for hunting, among other biological assets that made life possible. adapt to the different terrestrial environments of the planet.
Ultimately, researchers concluded that drylands contributed to the evolution of intelligent life on the planet, including abstract thinking, technology and science. Therefore, what were the most significant results of this study and what follow-up studies are currently underway or planned?
Dr. The Journey Tells The universe today“This very special condition (>500 million years of coexistence of continents, oceans and plate tectonics) is necessary on a planet with primitive life in order to develop intelligent technological and communicative life. This condition is very rarely achieved: only <0.003 to 0.2% of planets with any life can satisfy this condition.
Dr. Gerya continues: “We plan to study the evolution of water inside the planet in order to understand how the stability of the volume of oceans at the surface (implying the stability of the coexistence of oceans and continents ) can be maintained for billions of years (like on Earth). We also plan to study how long technological civilizations survive based on models of societal collapse. We also launched a project on the evolution of the state of oxygenation of the planetary interior and atmosphere in order to understand how atmospheres rich in oxygen (essential in particular for the development of technological civilizations) can form on planets with oceans, continents and tectonic plates. Progress in these three directions is essential but will depend greatly on the availability of research funding.
As noted, this study aimed to improve the Drake equation, which provides a multivariate equation that attempts to estimate the number of active and communicative civilizations (ACCs) that exist in the Milky Way. It was proposed in 1961 by Dr. Frank Drake to postulate several notions that he encouraged the scientific community to consider when discussing both how and why we have not heard of ACC and reads:
N=R* xfp xne xfI xfI xfvs xL
NOT = the number of technological civilizations in the Milky Way that can potentially communicate with other worlds
A.* = the average rate of star formation in the Milky Way
Fp = the fraction of these stars with planets
note = the average number of planets potentially capable of supporting life per star with planets
FI = the fraction of planets capable of supporting and developing life at a given time in its history
FI = the fraction of planets that develop life and evolve towards intelligent life
Fvs = the fraction of civilizations that develop technology capable of sending detectable signals into space
L = the length of time technological civilizations send signals into space
According to the study, the Drake equation estimates that the number of ACCs varies widely, between 200 and 50,000,000. As part of the study, the researchers proposed adding two additional variables to the equation of Drake based on their findings that plate tectonics, oceans and continents played a vital role in the development and evolution of complex life on Earth, which are as follows:
FOK = the fraction of habitable exoplanets that have notable continents and oceans
Fpt = the fraction of habitable exoplanets that have notable continents and oceans that also exhibit plate tectonics operating 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 towards intelligent life). So how important is adding two new variables to the Drake equation?
Dr. The Journey Tells The universe today“This allowed us to redefine and more correctly estimate the key term of the Drake equation fI – probability that a planet with primitive life will develop intelligent technological and communicative life. Originally, fI was (wrongly) estimated to be very high (100%). Our estimate is several orders of magnitude lower (<0.003 to 0.2%), which probably explains why we are not contacted by other civilizations.
Additionally, by entering these two new variables into the entire Drake equation, the study estimates a much smaller number of ACCs, between <0.006 and 100,000, in stark contrast to the original estimates of the Drake equation, from 200 to 50,000,000. So, what implications might this study have for the search for life beyond Earth?
Dr. The Journey Tells The universe today“This has three key consequences: (1) we should not really hope that we will be contacted (the probability of this is very low, in part because the lifespan of technological civilizations may be shorter than expected), (2 ) we should use remote sensing to search for planets with oceans, continents, and tectonic plates (COPT planets) in our galaxy based on their likely distinct (CO2-poor) atmospheres and surface reflectivity signatures (due of the presence of oceans and continents), (3) we must take care of our own planet and our civilization, both are extremely rare and must be preserved.
This study comes as the search for life beyond Earth continues to gain momentum, with NASA having confirmed the existence of 5,630 exoplanets as of this writing, nearly 1,700 of which are classified as super -Earths and 200 like rocky exoplanets. Despite these incredible numbers, especially since exoplanets began to be discovered in the 1990s, humanity has yet to detect any type of signal from an extraterrestrial technological civilization, which this study calls ACC.
The Wow! signal, which was a 72-second radio burst received by the Ohio State University Big Ear radio telescope on August 15, 1977. However, this signal has yet to be received since, with a complete absence of signals. With this study, scientists may be able to use these two new variables added to the Drake equation to help narrow the scope of the search for intelligent life beyond Earth.
Dr. Gerya concludes by saying 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 relationships between the long-term evolution of planetary interiors, the surface, the atmosphere and life.
How will these two new variables added to the Drake equation help scientists discover life beyond Earth in the years and decades to come? Only time will tell, and that’s why we do science!
As always, keep doing the science and keep looking!