spaceSpace and Physics

Scientists Searching For Extraterrestrial Life Hypothesize Humans Are In A "Galactic Zoo"


Crab Nebula in constellation Taurus. Supernova Core pulsar neutron star. Elements of this image are furnished by NASA. Allexxander/Shutterstock

For the last 50 years, astronomers have been searching for intelligence beyond Earth to no avail. Scientists at the biennial meeting of the Messaging Extraterrestrial Intelligence (METI) Project in Paris offer a relatively simple answer to explain the Great Silence: us humans are simply sitting in a “galactic zoo”.

“Perhaps extraterrestrials are watching humans on Earth, much like we watch animals in a zoo. How can we get the galactic zookeepers to reveal themselves?” explained Douglas Vakoch, president of METI, in a statement sent to IFLScience. “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. We can do the same with extraterrestrials by transmitting powerful, intentional, information-rich radio signals to nearby stars.”


It may sound far-out, but Vakoch tells IFLScience in a phone interview that the controversial “zoo hypothesis” was first presented in the 1970s by astronomer John Ball to explain the Fermi paradox, coined after Italian astronomer Enrico Fermi in the 1950s who asked: If life is so abundant, who is out there and why haven’t we heard from them yet? With an estimated 100 billion planets in the Milky Way, it’s possible that millions of habitable Earth-like planets could be housing life, yet whoever is out there sits (or floats around) in silence.

“Our meeting focused more on questions that can be discussed through biology, psychology, and sociology,” Vakoch told IFLScience. “What are the motivations of those beings out there? If there are civilizations doing exactly what we are – simply listening and not transmitting – it would be a very quiet universe. Might they be out there, and even knowing about us, but choosing not to respond?”

When it comes to interstellar communication, someone has to make the first move. Previous efforts to communicate with aliens, such as the golden record and pioneer plaque, have gone unanswered – a sign that perhaps extraterrestrial life may not understand written or pictographic forms of communication. Furthermore, spacecraft travel is incredibly slow when compared to radio signals that travel at the speed of light. That’s why the METI team is transmitting radio signals to space in the hopes that whatever is out there may be able to decode the messages.

 Voshak added that METI is preparing to send out multiple formats describing the 150th anniversary of the discovery of the periodic table.


“Finding regularity within nature is something that we would expect scientists on another planet to understand and know about,” he concluded.

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