Earth is very unique when it comes to its capacity to host life in this universe. And we have always wondered if we’re alone in the universe. Probably not. According to scientists, there are at least 36 active intelligent civilization only in our Galaxy. However, because of the time and the distance, we don’t really know if they exist or if they ever existed.
The calculations are based on the Drake equation, which was written by Frank Drake, astrophysicist and astronomer, back in 1961.
According to the authors of the study, “Drake developed an equation which in principle can be used to calculate how many Communicating Extra-Terrestrial Intelligent (CETI) civilizations there may be in the Galaxy. However, many of its terms are unknowable, and other methods must be used to calculate the likely number of communicating civilizations.”
So scientists found their own way of seeing things. The co-author of the study, Christopher Conselice, stated that the difference between their calculation and the previous ones, which were based on the Drake equation, is that they made simple assumptions about the development of life.
One of these assumptions is that life forms in a scientific way. This means that if there are the right conditions, then the life will start forming. This actually means that we can answer some of the most challenging questions, such as what fraction of planets in a habitable zone of a star will form life. We cannot answer this question unless we actually find life in the universe and that we have not done yet.
They developed something called the Astrobiological Copernican Principle in order to establish the strong and weak limits of life in the Galaxy. These equations actually include the history of how stars formed in our Galaxy and also the age of stars and what kind of metal the star has in its composition—also, the likelihood of stars hosting planets just like Earth in their habitable zones.