It’s the most ancient and greatest cosmic question: Is there anyone out there?
We have had the Drake Equation for years to help us understand the question but not an answer. A group of scientists from the University of Nottingham have now come up with a new “cosmic evolutionary”-based calculation – or, rather, an estimate – that suggests there may be at least 36 intelligent civilizations currently operating in the Milky Way galaxy.
The Milky Way, which is home to the Solar System, has 100 billion to 400 million stars and approximately one exoplanet for every star in our galaxy.
This paper was published today in The Astrophysical Journal. It examines the likelihood of communicating extra-terrestrial intelligent (CETI), civilizations in our Milky Way. It assumes intelligent life can occur on other planets as well as on our planet.
It makes many assumptions. makes way too many assumptions to be trusted with its expansive conclusions.
It takes five billion years for intelligent living to form on other planets. This assumption is key. This is a huge assumption. Another assumption is that a technological civilisation will survive at least 100 years, as ours has. It took 4.5 billion years for technology to emerge on Earth and be capable of communicating.
The number of civilizations is strongly dependent on the amount of time they have been actively transmitting signals of their existence into outer space, such as radio transmissions via satellites or TV.
Researchers call the calculation the “Astrobiological Coopernican Limit”, which says there could be 36 intelligent communicating civilizations in our galaxy that are at least 4.5 billion years old. It is based on Earth-like planets orbiting Sun-like stars. It includes:
Star formation history.
How common are stars rich in metals (like the Sun)
The likelihood of stars hosting Earth-like worlds in their habitable areas.
“The traditional method of estimating the number of intelligent civilisations relies upon making guesses about values related to life. However, opinions regarding such matters vary substantially,” stated Tom Westby, Assistant Professor at Nottingham’s Faculty of Engineering and lead author of the paper. Our new study reduces the assumptions and uses new data to give us a solid estimate for the number of civilizations in our galaxy.
At least 36 civilizations are estimated based on a positive outlook on how, when, and why life came into existence. There is also a large error bar. There could be many, many more alien civilisations. You could also think that there are none.
The authors point out that it takes approximately 17,000 light years to reach one of these 36 civilizations. Communication and detection are therefore impossible.
The difficult question of how long intelligent civilisations can survive is also a concern.
Christopher Conselice (Professor of Astrophysics, University of Nottingham), who led the research, said that “Searches to find extraterrestrial intelligent civilisations not only reveals how life forms but also gives us clues as to how long our civilization will last.” “If intelligent life is found to be common, this would indicate that our civilization could last for many hundred years,” said Christopher Conselice, Professor of Astrophysics at the University of Nottingham.
“Alternatively, it could be a sign that there are no active civilisations in our galaxy. This is bad news for our long-term existence.”
I wish you clear skies, wide eyes and clear skies.