Among the many questions that have puzzled scientists for decades, the question of whether we are alone in the universe is certainly one of the ones that most captivates us as a species. And among the many possibilities within this question, there is a particular uncertainty that assails many experts: why has humanity never been visited by extraterrestrials (that we know of)?
Now , two astrobiologists think they may have the answer: extraterrestrial civilizations – like those on Earth – come and go, so they could be doomed to stagnate or die before they get a chance.
The new hypothesis thus suggests that any species that advances far enough to gain control of a planet and expand into space is likely to face a similar set of existential dilemmas in its survival. Thus, as space civilizations grow in scale and technological development, they eventually reach a crisis point where innovation no longer keeps pace with energy demand. What comes after is the collapse, thus losing the opportunity to visit new worlds.
The only alternative path, according to the hypothesis, is to reject an “inflexible growth” model in favor of maintaining equilibrium, but at the cost of a civilization’s ability to expand across the stars.
In other words, civilizations “wiser” ones who recognize the dangers can prosper indefinitely, but without expanding enough to reach us, while others collapse and fail to make contact.
The Fermi Paradox
The new theory,published in the journal Royal Society Open Science, aims to explain the Fermi Paradox –based on the reflections made in 1950 by Nobel Prize-winning Italian physicist Enrico Fermi–, who wonders why, given that it is estimated that there are between 100.000 Y 400.000 million stars and at least 100.000 millions of planets in our galaxy, there have been no signs of extraterrestrial life.
“Civilizations collapse from exhaustion or reorient to prioritize homeostasis, a state in which cosmic expansion is no longer a target, making it difficult to detect from a distance,” astrobiologists Michael Wong of the Carnegie Institution for Science and Stuart Bartlett wrote in the study. , from the California Institute of Technology.
“Either of the two results would be consistent with the observed absence of civilizations ”, they added.
Cities grow in a “superlinear” way
Both analyzed previous studies that have shown that cities grow in a “superlinear” way – at a faster rate than linear – thanks to their social nature. This growth inevitably leads to crisis points – or singularities – that cause rapid declines in growth, followed by an even more precipitous collapse, which could end civilization.
“If a civilization develops the ability to understand its own trajectory, it will have a window of time to affect fundamental change to prioritize homeostasis and long-term well-being over inflexible growth ”, argues the document, calling this a “homeostatic awakening”.
From this point of view, civilizations that do not reach that awakening end up too busy, facing “asymptotic exhaustion” , a final crisis in which the time scale of the interval of singularity becomes smaller than the time scale of innovation”, they wrote.
The easiest alien civilizations to detect
According to the researchers, these depleted civilizations would be the easiest for humanity to detect, as they would be altering their environments and dissipating free energy unsustainably, with planetary-scale fluctuations showing the highest signal-to-noise ratio.
“This presents the possibility that a good part of the first detections of extraterrestrial life by humanity were of the intelligent type, although they did not know yet” , the researchers wrote.
Observing these depletions (provided humanity is long-lived enough to do so) would provide possible confirmation of part of our hypothesis,” they added.
Laws that govern life on Earth
The researchers stress, however, that their study is just a hypothesis, and that more research is needed to prove their theory. According to them, their conclusions are drawn from the observation of the laws that seem to govern life on Earth, and it is designed to “provoke debate, introspection and future work”.
The new theory adds to other scientific and popular suggestions. Among them are the many practical problems posed by interstellar travel; that aliens could be secretly visiting us; or that aliens arrived on Earth too early (or humans too early) in the life of the universe to make direct contact, according to Science Alert.
Another hypothesis, recently published by researchers at Peking Normal University, calculated the time it might take to establish contact with the aliens. They estimated that a signal sent by an advanced species could take up to 400.100 years to be received by another. So the reason we haven’t received a signal may simply be that the communication lifetime of humans hasn’t been long enough.
Beyond seeing the vast universe in search of other intelligent beings, the new theory could serve to reflect on what course we want to choose as a species. Faced with this question, surely many will not want to opt, at least hypothetically, for “asymptotic exhaustion”. So, will we be able to reorient ourselves to prioritize homeostasis?
Edited by Felipe Espinosa Wang.