Ever since the right technology came along, we started looking for life around other stars. But colleagues in the intellectual shop were never found. Maybe the point is that they are not there? If so, why?
Here's one rather depressing equation:
N = R * × fP × ne × f1 × fi × fc × L.
This is the Drake equation, describing the number of alien civilizations in the Galaxy with which we may one day be able to contact. Its conditions correspond to such values as the proportion of stars with planets, the proportion of planets where life can arise, the proportion of planets capable of supporting intelligent life, and so on. Using conservative calculations, the minimum result of this equation is 20. That is, there should be 20 intelligent civilizations in the Milky Way that we can hypothetically contact and which hypothetically can contact us. But as of today, we have not yet established contact with anyone. Moreover, we did not find anyone and continue to drift on our cosmic speck of dust, looking hopefully into the depths of space.
Drake's equation is an example of a deeper problem being debated in the scientific community. Given only the size of the universe and our knowledge that intelligent life has evolved - at least once - there must be signs of alien life in space. This is most often called the Fermi paradox, named after the physicist Enrico Fermi, who first pondered the contradiction between the high probability of the existence of alien civilizations and their apparent absence. Fermi summarized this with a succinct question: "Where is everyone?"
Perhaps this question was wrong. Probably a better option, albeit more worrisome, might be "What happened to everyone?" Unlike the question of the existence of life in the Universe, this one has a clearer answer: The Great Filter.
The emptiness of the universe
Alien life probably exists, but we don't see it. Consequently, the point may be that throughout the development of civilization, it encounters a serious and frequent obstacle that brings life to an end before it becomes intelligent and widespread enough for us to see it - and this is a kind of great filter.
This filter can take many forms. Perhaps the location of the planet in the Goldilocks zone, or the habitable zone - in a narrow strip around the star, where it is not too hot and not too cold for life to exist - and the presence of organic molecules on this planet capable of forming life is unlikely. We have observed many planets in the habitable zone of various stars (about 40 billion in the Milky Way), but it is possible that their conditions are not suitable for the origin of life.
The great filter can occur in the earliest stages of life. Perhaps when you studied biology in high school, you remember the phrase "mitochondria are the power plants of the cell." However, mitochondria were once separate bacteria that led an independent lifestyle. At some point, a single-celled organism on Earth tried to eat one of these bacteria, but instead of being digested, the bacterium entered into tandem with the cell and began to produce additional energy, which helped the cell develop in such a way that the formation of higher forms became possible over time. life. It is likely that such a surprising event occurred only once in the Milky Way.
In addition, the development of a large brain - like a human one - can be a filter.After all, we live on a planet that is inhabited by many creatures, but a human-like intelligence emerged on it only once. Probably, living beings on other planets simply do not need to develop such energetically demanding neural structures necessary for intelligence.
Will the Great Filter in the future await us?
All of the above possibilities suggest that the Great Filter is already far behind us, and humanity is a successful species that has overcome an obstacle that has become incredible for any other life. However, this may not be the case either. Life can constantly develop to our level, but go into oblivion as a result of some kind of catastrophe. The discovery of nuclear energy is a likely event for any advanced society, but it is capable of destroying us, just like a developed high-tech society. Using resources to create an advanced civilization is killing the planet itself: a prime example is global climate change, which scientists believe is almost entirely human-driven. Or it could be something completely unknown to us - a serious threat that we won't notice until it's too late.
Also, one of the saddest and even illogical assumptions about the Great Filter is that humanity should not look for alien life - especially one that has already reached a level of technological development similar to ours. If the Galaxy is truly empty and dead - speaking of another life - the chances that we have already passed the Great Filter are increased. The galaxy may be empty simply because another life could not pass some test that humanity managed to overcome.
If we ever find an alien civilization, but space is not teeming with intelligent life, this may mean that the Great Filter is still waiting for us somewhere in the future. In theory, the Galaxy should be teeming with life, but it is not. Another possibility is that other civilizations that should inhabit the Milky Way have been erased from the faces of their planets by some kind of catastrophe that we and our alien comrades still have to face.
Be that as it may, to this day we have not discovered other life, except for the one on Earth. While it may feel like we are alone at times, it only indicates that humanity's chances of long-term survival are slightly higher than it might seem.