Maybe not.
Scientists have calculated that there could be at least 36 active and communicating intelligent civilizations in our Milky Way galaxy, according to a new study. However, due to time and distance, we will never really know if they exist or have ever existed.
Previous calculations in this direction were based on Drake's equation, which was written by astronomer and astrophysicist Frank Drake in 1961.
"Drake has developed an equation that can in principle be used to calculate the number of intelligent extraterrestrial communicating civilizations (CETI) that there can be in the Galaxy," the authors wrote in their study. "However, many of its terms are unknowable and other methods must be used to calculate the likely number of communicating civilizations."
Scientists at the University of Nottingham therefore developed their own approach.
"The main difference between our calculation and the precedents based on Drake's equation is that we make very simple assumptions about the evolution of life," said study co-author Christopher Conselice, professor of at the University of Nottingham, in an email to CNN.
"One of them is that life is formed in a scientific way - that is, if the right conditions are met, life will be formed. This avoids the impossibility of answering questions such as" what fraction of the planets in a habitable zone of a star will form life? "" and "what fraction of life will evolve into intelligent life?" because they are not responsible until we have detected life, which we have not yet done. "
They developed what they call the Copernican astrobiological principle to establish weak and strong limits to life in the galaxy. These equations include the history of star formation in our galaxy and the age of the stars, the metal content of the stars, and the probability that the stars harbor Earth-like planets in their habitable zones where life could form. .
The habitable zone is at the right distance from a star, neither too hot nor too cold, where liquid water and life as we know it can be possible on the surface of a planet.
Of these factors, habitable zones are critical, but orbiting a calm and stable star for billions of years may be the most critical, said Conselice.
"The two Copernican astrobiological limits are that intelligent life is formed in less than 5 billion years, or after approximately 5 billion years - as on Earth where a communicating civilization was formed after 4.5 billion years "said co-author Tom Westby, assistant professor in the Faculty of Engineering at the University of Nottingham, in a statement.
The strong Copernican astrobiological limit is that life must form between 4.5 and 5.5 billion years, as on Earth, while the weak limit is that a planet takes at least 4 billion years to form the life, but it can form at any time afterwards, according to the researchers. .
"It is called the Copernican astrobiological principle because it assumes that our existence is not special," said Conselice. "In other words, if the conditions under which intelligent life on Earth also developed elsewhere in the Galaxy, intelligent life would develop there in the same way."
Based on their calculations using the strong Copernican astrobiological limit, they determined that there are probably 36 active and communicating intelligent civilizations across our galaxy. This assumes that life is shaped as it does on Earth - which is our only understanding at the moment. It also assumes that the metal content of the stars hosting these planets is equal to that of our sun, which is rich in metals, said Westby.
The researchers estimated that the strong limit is most likely because "it still allows intelligent life to form in a billion years after it was born on Earth, which appears to be a long time," said Conselice.
Another hypothesis of these potential civilizations is that they make their presence known in one way or another via signals.
Currently, we have only been producing signals such as radio transmissions from satellites and televisions for a short time. Our "technological" civilization is about a hundred years old. So imagine about 36 other people doing the same thing across the galaxy.
The researchers were surprised that the number was so small - but not zero. "It's quite remarkable," said Conselice.
Even if this study only focused on our galaxy, distance is an inhibiting factor. The researchers calculated that the average distance between these potential civilizations would be around 17,000 light years. Detecting these signals or sending communications using current technology would take so long that it would be almost impossible.
"The search for intelligent life should only produce a positive observation if the average lifespan of [communicating extra-terrestrial intelligence] in our galaxy is 3060 years old. That is, our communicating civilization here on Earth will have to persist for 6,120 years beyond the advent of long-range radio technology (about 100 years ago) before we can expect a [search for extra-terrestrial intelligence] two-way communication. "
According to the more relaxed hypotheses of the weak Copernic case, there would be a minimum of 928 communicating civilizations in our galaxy today, according to the study, which means more of them at shorter distances. It would only take about 700 years to detect.
Lifespan of a civilization
"It is clear that the lifespan of a communicating civilization is the key aspect of this problem, and very long lifetimes are necessary so that those of the Galaxy even contain some possible active contemporary civilizations," wrote the researchers in their study.
And then there is the question of survival. Do other potential civilizations have a lifespan as long as those of Earth?
If the search for this life reveals nothing within 7,000 light years, the researchers suggest that it could mean one of two things.
First, it could suggest that the lifespan of these civilizations is less than 2000 years - which could mean that ours is coming to an end.
Second, it could suggest that life on Earth is unique and occurs in a much more random process than the Copernican astrobiological limits established in the study.
Not all factors or limitations were included in the study, such as the fact that the small dwarf stars M these Earth-like planets can be in orbit can release harmful radiation "which would make life difficult", which is a matter of debate, Conselice told me. Dwarf M stars are common in our galaxy and are known to harbor rocky planets the size of Earth.
Then the researchers will look beyond our galaxy to see if life can exist beyond its borders.
"Our new research suggests that the search for intelligent extraterrestrial civilizations not only reveals the existence of how life forms, but also gives us clues to the duration of our own civilization," said Conselice.
"If we find that intelligent life is common, it would reveal that our civilization could exist much longer than a few hundred years, otherwise if we find that there are no active civilizations in our Galaxy, it is a bad sign for our own long-term. By seeking an intelligent extraterrestrial life - even if we find nothing - we discover our own future and our own destiny. "
