One of the core questions of humanity is whether or not we are alone in the universe. Humanity has looked to the stars for answers to that question and has struggled to come up with answers. The universe is impossibly vast even our own galaxy is mostly unknown. For the longest time scientists have used a formula known as the Drake Equation to analyze the mathematical likelihood of alien civilizations:
What do we need to know about to discover life in space? How can we estimate the number of technological civilizations that might exist among the stars? While working as a radio astronomer at the National Radio Astronomy Observatory in Green Bank, West Virginia, Dr. Frank Drake conceived an approach to bound the terms involved in estimating the number of technological civilizations that may exist in our galaxy. The Drake Equation, as it has become known, was first presented by Drake in 1961 and identifies specific factors thought to play a role in the development of such civilizations. Although there is no unique solution to this equation, it is a generally accepted tool used by the scientific community to examine these factors.
-- Frank Drake, 1961
These numbers can be mind-boggling. The Milky Way, home to our Solar System, is estimated to have 100 billion to 400 billion stars, and roughly one exoplanet per star in our galaxy. Now, a group of scientists at the University of Nottingham believe that they’ve come up with a new “cosmic evolution”-based calculation that suggests the possibility that there are likely to be at least 36 ongoing intelligent civilizations in our Milky Way galaxy.
Their study, which was published in the Astrophysical Journal , assumes that life for other Communicating Extra-Terrestrial Intelligent (CETI) would have evolved in ways similar to our own. Much of the study is based on similar assumption between other civilizations and our own. It took 5 billion years for humans to develop communication technology so it stands to reason that other species would have a similar timeline.
“The classic method for estimating the number of intelligent civilizations relies on making guesses of values relating to life, but opinions about such matters vary quite substantially,” said Tom Westby, Assistant Professor, Faculty of Engineering at the University of Nottingham, and lead author on the paper. “Our new study simplifies these assumptions using new data, giving us a solid estimate of the number of civilizations in our galaxy.”
Unfortunately, these potential 36 civilizations is around 17,000 light-years, so detection and communication is impossible with current technology. Also, there's a darker question about how long these societies survive.
“Searches for extraterrestrial intelligent civilizations not only reveals the existence of how life itself forms, but also gives us clues about how long our own civilization will last,” said Christopher Conselice, Professor of Astrophysics at the University of Nottingham, who led the research. “If we find that intelligent life is common then this would reveal that our civilization could exist for much longer than a few hundred years.”
“Alternatively, if we find that there are no active civilizations in our galaxy it is a bad sign for our own long-term existence.”