After the discovery of exoplanets, the existence of alien life has transformed from just a belief into a probability. According to scientists, it is possible that alien civilizations existed long ago.
The publication News Everyday reports that scientists have approximated for a long time on how many stars exist in the universe. According to Adam Frank of the University of Rochester and co-author of a new study, the question of the existence of advanced civilizations elsewhere in the universe has been answered with "three large uncertainties in the Drake equation."
It is unknown for the current level of science how many of stars could potentially harbor life. It is also unknown how often life could evolve and lead to intelligent beings and how long an alien civilization might last before becoming extinct.
NASA's Kepler satellite and other planetary searches have found that around one fifth of stars in the universe have habitable planets. On these planets, life as people know it could be supported by the temperature range.
In creating a new theory about alien life in the universe, Adam Frank collaborated with Woodruff Sullivan, who works at the astronomy department and astrobiology program at the University of Washington. According to their study, life in universe might have been plentiful in the universe once, but people cannot come in contact with any alien civilization today because they might have all died out.
Frank also said that scientists cannot base their estimation of alien civilizations lifespan on the fact that humans have survived just on rudimentary technology for roughly 10,000 years. Scientists have tried to calculate the odds against the existence of life in the cosmos and found that mankind might be unique in the universe only if the odds of a civilization growing in a habitable planet are less than about one in 10 billion trillion. This is incredibly small, according to Frank's blog post.
This means that there are good odds that other intelligent, technology-producing species have evolved before man on Earth and some might still exist in the universe. The findings were published in the journal Astrobiology on April 22, 2016.