Maybe we are not.
According to a new study, scientists calculated that there may be at least 36 active, communicating intelligent civilizations in our Milky Way galaxy. However, due to time and distance, we may never know if they exist or are present.
Previous calculations in these lines were based on the Drake equation written by astronomer and astrophysicist Frank Drake in 1961.
“Drake has developed an equation that can be used in principle to calculate how many Non-Terrestrial Intelligent (CETI) Communication civilizations can exist in the Galaxy,” the authors wrote in their work. “However, many of its terms are unknown, and other methods should be used to calculate the number of possible communication civilizations.”
Thus, scientists at Nottingham University have developed their own approach.
“The main difference between computing and the predecessors based on the Drake equation is that we make very simple assumptions about how life evolved,” said his colleague Christopher Conselice, a professor of astrophysics at the University of Nottingham, in the CNN email. Said.
“One of them is the scientific formation of life – if the right conditions are met, then life is created. This is,” which fraction of planets in a livable part of a star will make life? “And” which part of life will turn into smart life? ” because these cannot be answered until we detect the life we have not yet done. ”
They have developed what they call the Astrobiological Copernican Principle to create weak and strong boundaries on life in the galaxy. These equations include the history of star formation in our galaxy and the ages of the stars, the metal content of the stars, and the possibility of stars that contain Earth-like planets in their habitable regions where life can occur.
The livable region is the right distance from a star, not too hot or too cold, life that liquid water and a planet knows that it can be possible on its surface.
The habitable regions are critical from these factors, but it may be the most critical point for a silent and fixed star to orbit over billions of years.
“The two Astrobiological Copernican boundaries are that smart life occurs in less than 5 billion years, or about 5 billion years later – 4.5 billion years later, the world where communication civilization occurred,” said assistant professor Tom Westby at the engineering faculty at Nottingham University.
The Astrobiological Copernicus Strength limit is that life should occur 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 life, but it can occur at any time thereafter. .
“It is called the Astrobiological Copernican Principle because it assumes that our existence is not special,” Conselice said. Said. “So, if smart life in the world had developed elsewhere in the Galaxy, smart life would have developed similarly there.”
Based on their calculations using the Astrobiological Copernicus Strong boundary, they determined that 36 active and communicative smart civilizations are likely in our galaxy. This assumes that life is formed as it is on Earth – this is our only understanding right now. Westby also assumes that the metal content of the stars that contain these planets is equal to the content of our sun, which is rich in metals.
The researchers believed that the strong boundary was most likely, because it allows intelligent life to form within a billion years after being on Earth, which seems to be a lot of time, ”said Conselice.
Another assumption of these potential civilizations is that they somehow announce their presence through signals.
We are currently producing signals such as radio broadcasts from satellites and televisions for only a short time. Our “technological” civilization is about a hundred years old. So consider 36 other people doing the same thing in the galaxy.
The researchers were surprised that the number was very small, but not zero. “This is quite remarkable,” said Conselice.
Although this study only looks at our galaxy, it is a distance blocking factor. The researchers calculated that the average distance between these potential civilizations would be approximately 17,000 light years. It will take long enough to be able to detect these signals or send communications using existing technology.
“The search for smart life, but the average life span [communicating extra-terrestrial intelligence] There are 3,060 years in our galaxy. So, our civilization here in the world will have to continue for 6,120 years beyond the emergence of long-range radio technology (about 100 years ago). [search for extra-terrestrial intelligence] two-way communication. “
Under the more comfortable assumptions of the weak Copernican case, there would be a minimum of 928 civilizations, communicating in our galaxy today, which means more from a closer distance. Approximately 700 years are required to detect this.
The life span of a civilization
“It is clear that the lifetime of a communicating civilization is the key to this problem, and people in the Galaxy need very long lives to include even a few possible active contemporary civilizations.”
And then there is the problem of survival. Are other potential civilizations as long as on Earth?
If this quest for life does not reveal anything at 7,000 light years away, researchers suggest that this could mean one of two things.
First, we can say that the lifespan of these civilizations is less than 2,000 years – this may mean that ours is nearing its end.
Second, he may suggest that life on Earth is unique and occurs in a much more random process than the Astrobiological Copernican Boundaries set in the study.
Not all factors or limitations are included in the study, for example, small M-dwarf stars that these Earth-like planets can orbit can emit harmful radiation that will “make life difficult”, which is a controversial issue, I said Conselice. M-dwarf stars are common in our galaxy and are known to host rocky planets worldwide.
Later, researchers will look beyond our galaxy to see if life exists outside its limits.
“Our new research shows that the search for extraterrestrial intelligent civilizations not only reveals the existence of life, but also gives us clues about how long our civilization will last.” Said.
“If we realize that smart life is common, it reveals that our civilization may have existed for more than a few hundred years, alternatively if we find that there are no active civilizations in our Galaxy, this is a bad sign for us for a long time. By looking for extraterrestrial smart life – even if we cannot find anything – we discover our own future and fate. “