Does alien life exist? If the answer is yes, why haven't they contacted Earth yet?
During a meeting organized by the organization Messaging Extraterrestrial Intelligence (METI) in Paris, scientists discussed the reason behind alien inactivity or what experts call "The Great Silence."
Earth May Be Part of a 'Galactic Zoo'
One of the possibilities explored is the scenario of a "galactic zoo." Perhaps, scientists suggest, intelligent extraterrestrial beings already know about life on Earth and are simply watching humans from afar, purposefully staying out of the radar.
This explanation is called the "zoo hypothesis" and it was introduced in the 1970s by astronomer John Bell.
It's akin to the way people watch caged animals in the zoo, Douglas Vakoch, METI president, points out in a statement to IFLScience. Now, the question is, how can humans get the aliens to reveal themselves to the people they're watching?
"If we went to a zoo and suddenly a zebra turned toward us, looked us in the eye, and started pounding out a series of prime numbers with its hoof, that would establish a radically different relationship between us and the zebra, and we would feel compelled to respond," he continued. "We can do the same with extraterrestrials by transmitting powerful, intentional, information-rich radio signals to nearby stars."
Vakoch adds that METI is planning to send out a message that describes the 150th anniversary of the periodic table in various formats.
In doing this, it's possible that any alien who might be observing the planet could be compelled to respond to the undeniable sign of intelligent life on Earth.
Are Aliens Out There?
Cyril Birnbaum and Brigitte David cited at the METI meeting that the presence of alien life is a relevant subject that affects the entire species since it's related to humankind's place in the universe, according to Forbes.
Milky Way alone is home to billions of planets and beyond this galaxy, there is an infinite number of more planets. The likelihood of having just a single planet out of billions and billions of them have ever developed life seems to be extremely small.
Scientists have been trying to find evidence of alien life for decades. In 1950, physicist Enrico Fermi summed up the contradiction in what's now known as the Fermi Paradox: if extraterrestrial life is probable, why have none contacted Earth?
Another explanation discussed during the meeting in Paris is the "galactic quarantine," which is the theory that extraterrestrials are keeping out of sight because they recognize that finding out about alien life could be detrimental to humankind.
For now, no one has the answers.