Search for alien life has taken human curiosity to far ends of the cosmic world. A new study, however, suggests that the distance might not be the problem to find such signs. Instead, we might have to go back in time to look for one, as it proposes that intelligent alien civilizations in our galaxy might already be dead on the timescale.
Now published to the arXiv database, a new study conducted by three Caltech physicists and one high school student tries to estimate the emergence and death of intelligent life in the Milky Way galaxy. The study uses modern astronomy and statistical modeling to map these signs across time and space.
The study is based on the Drake equation, first proposed by Frank Drake, the founder of Search for Extraterrestrial Intelligence, back in 1961. The equation has found a mention in Carl Sagan¡¯s Cosmos miniseries and takes into account several mystery variables to estimate the number of extraterrestrial civilizations in the Milky Way galaxy.
The new paper is a 2020 update to it, only much more practical, a report by LiveScience explains. The study identifies the ideal location and time for alien societies to have existed in the galaxy and interestingly, it does not coincide with the era of humans on Earth.
From their statistical modelling, the researchers found that the probability of life emerging in the Milky Way is at its peak at a distance of about 13,000 light-years from the galactic center, mostly due to the presence of stars like our Sun in the region. In comparison, Earth is 25,000 light-years away from the galactic center.
The study also determines the ideal time for the civilisation to have formed. It says that it is likely that intelligent alien species emerged around 8 billion years after the galaxy formed. On Earth, human civilization took form about 13.5 billion years after the Milky Way formed.
To come to this conclusion, the researchers considered several factors that can likely affect the evolution of intelligent life. These include the prevalence of sun-like stars around the host planet, other such life-harboring conditions as well as the estimated time required for intelligent life to evolve.
But most importantly, the scientists considered a very unpredictable, yet important factor in their estimates - the self-annihilation tendency of intelligent creatures. Merely speculating on several reasons, including those like a nuclear holocaust or climate change triggered by such societies, can increase the chances of finding such alien societies across space and time stamps.
The research thus explains the chances of humans being a frontier civilization in the Milky Way galaxy. Another intelligent species like ours might have vanished long ago, though the study does mention chances of a less evolved alien species still out there. Only not smart enough to reach out to us.