New theory claims humans are 'probably' the only intelligent life in our galaxy
Have you ever gazed up at the night sky and wondered if humans are the only intelligent life in this vast universe? The twinkling stars, distant galaxies, and the sheer expanse above us evoke a sense of mystery and awe.
It’s a question that has intrigued humanity for centuries, driving scientists, philosophers, and dreamers to explore the cosmos and seek answers to one of our most profound questions.
What lies beyond Earth in our Milky Way galaxy? Are there other forms of life out there, sharing the same curiosity and wonder?
What does intelligent life need?
New research brings us closer to understanding why we lack evidence of advanced extraterrestrial civilizations.
Dr. Robert Stern, a geoscientist at the University of Texas at Dallas, and Dr. Taras Gerya from the Swiss Federal Institute of Technology in Zurich, led the study.
“Life has been around on Earth for about 4 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,” said Stern. “Plate tectonics really jump-starts the evolution machine, and we think we understand why.”
Understanding the Drake Equation
In the 1960s, Dr. Frank Drake, a pioneer in the search for extraterrestrial intelligence, developed an equation to estimate the number of intelligent civilizations in our galaxy capable of communication.
N = R* x fp x ne x fl x fi x fc x L
N: The number of civilizations in the Milky Way galaxy whose electromagnetic emissions (radio waves, etc.) are detectable.
R*: The number of stars formed annually.
fp: The fraction of those stars with planetary systems.
ne: The number of planets per solar system with an environment suitable for life.
fl: The fraction of suitable planets on which life actually appears.
fi: The fraction of life-bearing planets on which intelligent life emerges.
fc: The fraction of civilizations that develop a technology that produces detectable signs of their existence.
L: The average length of time (years) such civilizations produce such signs.
The above equation is known as the Drake Equation. Now famous in both scholastic and scientific circles, it considers variables like the rate of star formation and the fraction of stars with life-supporting planets.
Despite its optimistic predictions, we still have no contact with extraterrestrial civilizations. This mystery is called the Fermi Paradox. Named after nuclear physicist Dr. Enrico Fermi, it asks, “Where is everyone?”
Prerequisites for intelligent life
Dr. Stern and Dr. Gerya suggest that the Drake Equation may have overlooked the vital role that large oceans and continents play in fostering intelligent life.
According to their research, active, communicative civilizations (ACCs) not only need a stable environment but also long-term geological processes that shape and sustain their planet’s surface.
Specifically, they argue that plate tectonics, the slow but powerful movement of a planet’s outer shell, is crucial for the evolution of complex life forms.
Deconstructing plate tectonics
Plates aren’t just for dinner. In the realm of geosciences, plate tectonics refers to the Earth’s crust and upper mantle, which are fragmented into pieces that move ever-so-slowly over geological time scales.
Imagine continents as colossal rafts, floating and colliding, causing mountains to rise and oceans to form.
“It is much more common for planets to have an outer solid shell that is not fragmented, which is known as single-lid tectonics,” Stern said.
“But plate tectonics is much more effective than single-lid tectonics for driving the emergence of advanced life-forms.”
Without such dynamic processes, life may struggle to evolve beyond simple, microbial forms.
Refurbishing the Drake Equation
In their study, Stern and Gerya suggest refining a Drake equation factor, fi. This factor represents the fraction of life-bearing planets where intelligent life emerges.
They argue it should consider the necessity of large oceans, continents, and plate tectonics for over 500 million years on those planets.
“In the original formulation, this factor was thought to be nearly 1, or 100% – that is, evolution on all planets with life would march forward and, with enough time, turn into an intelligent civilization,” Stern said. “Our perspective is: That’s not true.”
To put it simply, not every planet with life will necessarily develop an intelligent civilization. They suggest that the factor should consider the presence of significant continents, oceans, and long-lived plate tectonics.
This adjustment could drastically alter our estimates of the number of planets where advanced civilizations might arise.
Intelligent life and galactic conditions
Their revised formula starkly shrinks the potential fraction of exoplanets with optimal conditions for advanced life.
According to Stern, the fraction of exoplanets with enough water and prolonged plate tectonics is likely much tinier than previously thought.
How tiny? Well, they estimate the values range from as low as 0.0002 to 0.01 for the volume of water and less than 0.17 for the duration of lasting plate tectonics.
“When we multiply these factors together, we get a refined estimate of fi that is very small, between 0.003% and 0.2%, instead of 100%,” Stern said.
“This explains the extreme rareness of favorable planetary conditions for the development of intelligent life in our galaxy and resolves the Fermi paradox.”
These numbers imply that the conditions necessary for the emergence of intelligent life are exceedingly rare.
Our role in the cosmos might just be a stroke of extraordinary luck. Stern’s research suggests that the perfect alignment of geographical and geological factors required to birth intelligent life forms like us is more of a rare cosmic jackpot than a universal rule.
This understanding could potentially solve the Fermi Paradox by explaining why we haven’t encountered other advanced civilizations despite the vast number of stars and planets in the universe.
Searching the galaxy for intelligent life
NASA has confirmed well over 5,000 exoplanets in the Milky Way alone, but currently, we aren’t equipped to detect plate tectonics on these alien worlds.
Despite this limitation, scientists, including UT Dallas planet hunter Dr. Kaloyan Penev, continue their relentless pursuit of habitable planets.
The findings of Stern and Gerya might just shine a new light on their search, offering new parameters and considerations for identifying planets that could host advanced life.
“Biogeochemistry posits that the solid Earth, particularly plate tectonics, speeds up the evolution of species,” Stern said.
“Studies like ours are useful because they stimulate thinking broadly about larger mysteries and provide an example of how we can apply our knowledge of Earth systems to interesting questions about our universe.”
Expanding our cosmic comprehension
This research reminds us how much we still have to learn about the universe. It encourages us to think beyond Earth and consider how our planet’s geological systems can offer insights into cosmic mysteries.
Earth’s history, with its tectonic movements, volcanic eruptions, and changing atmosphere, reflects processes that might happen on faraway worlds.
By studying our planet, we learn about the potential for life and the workings of other planets.
The next time you look at the stars, remember that each one might have its own world, full of stories to tell.
Picture the possibilities: planets with unique landscapes, climates, and maybe even life forms different from ours. The universe is vast and full of wonders.
Our journey to understand it has just begun. As we learn more, we find more questions and discover that the cosmos is more complex and beautiful than we ever imagined.
The full study was published in the journal Scientific Reports.
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