Humanity is the only intelligent civilization in the entire galaxy: A disappointing conclusion of scientists

Astronomer Frank Drake created an equation to estimate the number of civilizations in the Milky Way capable of communicating with us. Drake derived this equation in 1961. But over time, the Drake equation began to be criticized for making too broad assumptions and ambiguous parameters, which often led to overly optimistic estimates of the number of civilizations (N). His equation also did not correspond to the Fermi paradox: if intelligent life is widespread, then why do we not find traces of it? A new study published in Scientific Reports suggests a solution to Drake’s formula, adding two new factors that may explain the Great Silence.

Are there extraterrestrial civilizations? Photo: Unsplash

Planetary scientists Robert Stern from the University of Texas at Dallas and Taras Gerya from the Swiss Higher Technical School of Zurich suggest that the presence of continents and oceans and long-term plate tectonics are crucial for the development of civilizations. They propose adding two factors to the equation: the proportion of planets with significant continents and oceans and the proportion of those where plate tectonics have been in effect for at least 500 million years. According to Stern and Gerya, planets with continents, oceans and long-term plate tectonics are extremely rare, and this should be taken into account in the Drake equation. As a result of the recalculation, the value of N has become significantly smaller.

Mistake in the Drake equation

The traditional Drake equation estimates the number of active extraterrestrial civilizations, taking into account the rate of star formation, the proportion of stars with planets, the number of habitable planets, the proportion of planets with intelligent life, and so on. The proposed changes clarify estimates of how many planets can develop life and how many civilizations have technologies that can be detected.

The researchers claim that large oceans and the Earth’s transition from a stable surface layer to modern plate tectonics about 1 billion years ago were critical for the development of complex life. This geological activity not only created the conditions for the emergence of life, but also contributed to its evolution, which forced creatures to adapt to environmental changes, eventually giving rise to people capable of developing complex societies and creating technologies. Technology is evolving from everyday needs such as tool making, agriculture, clothing making, and weapon making. Fire and electricity are necessary for the development of intelligent civilizations. Complex civilizations are unlikely to arise in a purely oceanic environment.

Only 2 out of 1000 suitable planets

To find out how likely it is that the planet will have both continents and oceans, scientists have studied how much water is needed on the surface of the planet. They found that an Earth-sized planet should have between 0.007% and 0.027% of its mass in water. They then compared this with the total possible water content of the planets, which ranges from 0% to 3.8% or even from 0% to 55%, depending on their formation. For plate tectonics, they used data showing that only about 33% of the planets have the right chemicals to form sufficiently dense tectonic plates. Of these, only half are large enough and have sufficient gravity to maintain plate tectonics.

Exoplanet Proxima d in the artist’s impression. Source: ESO/L. Calçada

Taking into account these new factors, the researchers estimate that the probability of continents, oceans and plate tectonics on the planet is very small – less than 0.2%. This means that out of every 1,000 planets, only two may be suitable. 

Advanced civilizations are extremely rare

Given these new data, the modified Drake equation shows that advanced civilizations are very rare. The probability of having suitable conditions ranges from 0.0034% to 0.17%. This means that in our galaxy there may be from 0.006 to 100 thousand active civilizations capable of communication, and the real number is likely to be less due to the limited time during which these civilizations can communicate due to possible social collapse or extinction.

Taras Gerya noted that although the upper limit of 100,000 seems large, the lower estimate is more important. Since the lower estimate is very close to zero, there is a high probability that there will never be any communication between these civilizations.

Earlier, we reported on how scientists found seven candidates for Dyson spheres.

According to