In 1950, physicist Enrico Fermi raised a very important question about the universe and the existence of extraterrestrial life.
Given the size and age of the universe, he said, and the statistical
probability of life emerging in other solar systems, why is it that
humanity has not seen any indications of intelligent life in the cosmos?
This query, known as the
Fermi Paradox, continues to haunt us to this day.
If there are indeed billions of star systems in our galaxy, and the
conditions needed for life are not so rare, then where are all the
aliens?
According to a
recent paper
by researchers at Australian National University's Research School of
Earth Sciences, the answer may be simple: They're all dead. In what the
research team calls the "Gaian Bottleneck," the solution to this paradox
may be that life is so fragile that most of it simply doesn't make it.
To put this in perspective, let's first consider some of the numbers.
As of the writing of this article, scientists have discovered
2,049 planets in 1,297 planetary systems, including 507 with multiple planets. In addition, a
report issued in 2013
by the Proceedings of the National Academy of Sciences of the USA
indicated that, based on Kepler mission data, there could be as many as
40 billion Earth-size planets orbiting in the habitable zones of
sun-like stars and red dwarfs within the Milky Way and that 11 billion
of these may be orbiting sun-like stars.