Answers to the question of existence of alien civilizations and the «silence» that prevails in the Universe attempt to give researchers from the USA, renewing the famous Equation Drake (Drake Equation) where calculates the possible existence of extraterrestrial civilizations on the galaxy and concluding that, if they exist, most of them have destroyed themselves.
The question of the existence of extraterrestrial life, intelligent or not, is one of the oldest in science, and as the available data and scientific tools increase, many scientists seem convinced that it is more likely that extraterrestrial civilizations have evolved than not; especially given the numbers of exoplanets that are being discovered, many of them around Sun-like stars and in orbits that could be conducive to the existence of life as we know it.
In this context, researchers are attempting to extend and develop the work of Frank Drake since 1961: the American astrophysicist and his colleagues had developed an equation (now known as the Drake Equation) for calculating the probability of the existence of extraterrestrial civilisations, given everything that was known at the time about space and astronomical objects. Factors taken into account were the estimated number of exoplanets and of star systems, how many planets were likely to support life, etc.
A lot of «water has flown under the bridge» since then: A large number of exoplanets have been discovered, many of which are in the so-called «zones Goldilocks» of their stars, while more is known about the age of the universe and the conditions after the Big Bang.
Sto as part of this research, published in arXiv, researchers from the Caltech but also a US high school student, updated the equation using modern astronomical and statistical models to depict the emergence and death of intelligent life forms in our galaxy. This new paper, as noted in a relevant publication of Live Science, is particularly practical in that it tells where and when life is most likely to appear in the galaxy, and suggests that the most important factor in its presence is the tendency of intelligent beings to self-destruct.
As the researchers note, many of the numbers that were unknown as to the factors suggested in 1961 are now known. As part of their research, they looked at several factors thought to influence the development of intelligent life, such as the frequency of supernova, the time required, the frequency of Sun-like stars with Earth-like planets; and, as mentioned above, the tendency that advanced civilizations are thought to have for self-destruction.
Over time, their models have shown, taking these known factors into account, that the probability of life reaches its highest point within 13 000 light-years of the centre of the galaxy and 8 billion years after its formation. To understand the analogies, suffice it to say that the Earth is 25,000 light years from the center and human civilization appeared on our planet about 13.5 billion years after the formation of the galaxy.
The implication is that we are, as a civilization, somewhat «late» in the hypothetical «club» of advanced civilizations in our galaxy; but, if one assumes that life does indeed appear relatively often and develops intelligence, then «out there» there are probably many other civilizations, probably concentrated in that 13,000 light-year band where many stars like ours meet.
However, if this is the case, the question arises: How do we explain the Fermi's paradox; It is the logical paradox developed by the physicist Enrico Fermi and it has to do with the absence of evidence for the existence of extraterrestrial civilizations, despite measurements suggesting that the number of planets capable of supporting life in our galaxy (possibly advanced) is possibly in the billions - the so-called «Great Silence».
According to this research, which updates the Drake Equation, most of the other civilizations that may exist in our galaxy today will be relatively young, and therefore without the possibility of contact with us; because intelligent life seems to have a tendency to self-destruct over time: Among the most striking findings of the research is that, even if the galaxy reached its peak in terms of civilizations 5 billion years ago, most of the civilizations that existed then will probably have self-destructed; making our galaxy a vast «graveyard» of ancient alien civilizations, succeeded by others.
«Since we cannot rule out a high probability of catastrophe, (this result) suggests that most potential evolved life within the galaxy may still be very young,» the researchers suggest.
Of course, how often hypothetical civilizations self-destruct is a question of how often they unknown variable, but which has a very important role to play in how widespread the phenomenon of the emergence of civilisations is: As scientists estimate, even a low probability of catastrophe (nuclear holocaust, climate change derailment, etc.), in any time zone, leads to the conclusion that most of the civilizations in our galaxy have already been destroyed.
In summary, the researchers estimate that the hypothetical civilisations of our galaxy will probably be either very young (and without the ability to travel far into space or give us detectable signals/traces - broadly speaking, around our levels) or very old and therefore extinct.
In any case, however, the aim of scientists, as they stress, is not to focus on numbers as to the possible existence of intelligent life forms, but to «developing a statistical, detailed galactic picture of the potential trend of intelligent life development over a period of about 20 billion years»- i.e. a «tool» that could be useful to others working on the explanation of the Fermi Paradox.
Science fiction? Possibly yes; it is no coincidence that the scenario of ancient civilizations leaving behind ruins and «carcasses» (sometimes even dangerous ones) is particularly common in SF, as countless books, films, series and video games have been based on it. One thing is for sure, however, no one can know what might be waiting for us «out there» (if we ever make it there).
