In 1961, astronomer Frank Drake proposed the Drake equation to calculate the number of higher intelligent civilizations in the Milky Way and beyond that might come into contact with us. Drake’s equation estimates range in size from zero to billions. Christopher Conselice, an astronomer at the University of Nottingham, thinks the equation is more of a thinking tool than it really solves the problem.
He and his colleagues published a paper in the journal Astrophysical Journal, using new data and assumptions to improve the Drake equation. They hypothesized that life could evolve over billions of years on Earth-like planets.
This hypothesis, known as the Astrobiological Copernican Principle, is fair to the right conditions, from chemical reactions to star formation.
Under the strictest assumptions, civilizations formed between 45 and 5.5 billion years of star formation on Earth-like planets.
They calculated that there are 4 to 211 civilizations in the Milky Way today that can communicate with other civilizations, and 36 is the most likely number. According to the research team, our Earth civilization needs to survive another 6120 years before it can communicate in both directions with other higher civilizations.