New Estimate Suggests Only 36 Active Extraterrestrial Civilizations May Exist in Our Galaxy
TL;DR
New research suggests there could be as few as 36 active extraterrestrial civilizations in the Milky Way galaxy. Based on the idea that intelligent life evolves over 5 billion years, scientists from the University of Nottingham estimate that the nearest alien civilization could be 17,000 light-years away. However, current technology makes communication over these distances unlikely. Not all researchers agree with these findings, as the origin of life on Earth may not necessarily reflect the development of life on other planets. The ongoing search may provide insights into the long-term survival of life on Earth.
For centuries, scientists have sought out cosmic evidence to determine if we’re alone in the universe. New estimates now suggest there might indeed be other active civilizations—but not many.
In the 1960s, astronomer Frank Drake introduced the Drake equation, a formula used by many researchers to estimate the likelihood of communicating with extraterrestrial civilizations in our Milky Way galaxy.
Drake’s equation involves seven key variables, ranging from the number of habitable exoplanets in the galaxy to the time it takes for intelligent life to develop. These variables are extremely difficult to define. As a result, the formula acts more as a framework for estimating the odds of finding life, with previous estimates varying from none to over a billion civilizations.
Now, two researchers from the University of Nottingham in the U.K., assuming life takes the same amount of time to evolve elsewhere in the galaxy as it did on Earth, have narrowed that estimate to just 36 extraterrestrial civilizations.
“There should be at least a few dozen active civilizations in our galaxy, assuming it takes about 5 billion years for intelligent life to emerge on other planets, similar to Earth,” astrophysicist Christopher Conselice said in a statement. The team referred to this calculation as the “Astrobiological Copernican Limit.”
Using this method as a basis, the researchers developed multiple scenarios: In one scenario, intelligent life takes no more than 5 billion years to form, while in a stronger scenario, it takes between 4.5 and 5.5 billion years for intelligent life to emerge.
Based on their strong scenario calculations, there could be anywhere between four and 211 complex civilizations capable of sending signals into space, with 36 being the most likely number. The nearest of these civilizations would likely be about 17,000 light-years from Earth, orbiting a low-mass M-type dwarf star.
However, this doesn’t look promising for our chances of contacting these distant extraterrestrial civilizations. Today’s technology makes communication over such vast distances impossible.
Not everyone agrees with the findings, which were published in The Astrophysical Journal. According to The Guardian, some researchers are skeptical of the analysis. Oliver Shorttle from the University of Cambridge told the outlet that more factors need to be considered—such as the precise way life arose on Earth—before drawing conclusions from these results.
So, what might this mean for the future of life on Earth? The ongoing search for life elsewhere could provide insights into our own survival.
“If we discover that intelligent life is common, this could suggest that our civilization might last much longer than just a few hundred years,” Conselice said. “On the other hand, if we find no active civilizations in our galaxy, it could be a troubling sign for our own long-term prospects.”
