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By Seth Shostak
Ask your friends why scientists have not found extraterrestrials, and you I can be sure that at least one of them gives the following answer: Humans are not worthy.
We are flawed beings. We threaten ourselves regularly, not to mention other species and the environment. This does not sound very civilized and offers a plausible explanation for the lack of contact. Maybe the aliens know that we are here, but do not want to deal with us ̵
This idea is endlessly appealing. It is also old. In 1973, MIT radio astronomer John Ball published a paper stating that the success in exposing cosmic companies was not due to a lack of extraterrestrials. It was because these alien spirits have agreed on a policy of release.
They have kept their distance, not because we are imperfect, but because of our right to pursue our own destiny. Diversity is something that is supposed to be of value to everyone in the cosmos, so the life-sustaining worlds should be left to their own evolutionary development.
It may occur to you that Ball's idea sounds like Star Trek's famous "main instruction" prohibiting members of the Federation in space from doing anything that could upset other cultures or civilizations, even if that interference was well intentioned. The MIT astronomer suggested that we did not make contact with extraterrestrials, not because we are unworthy, but because we are worthy – just like endangered eels.
Ball went on and suggested living in a metaphorical zoo – a kind of cosmic Eden. The aliens of the galaxy have arranged things somehow so that our planet is shielded by disposable bars in front of them: they can watch us, but we can not watch them.
One nice thing about this guess is that it's a solution to a long-standing puzzle known as Fermi's Paradox. Razed almost 70 years ago by physicist Enrico Fermi, it rests on the fact that the universe is very old. So, if intelligent life is commonplace, some of it is certainly so advanced that it has populated the entire galaxy. We should see evidence of aliens everywhere. The fact that we could not be explained by Ball's hypothesis – we are deliberately isolated.
The zoo hypothesis was recently published in the news because it also justifies an activity called METI, aka Messaging Extraterrestrial Intelligence. Put simply, METI practitioners send radio signals into space hoping to provoke a response from aliens who might pick them up. In 2017, a Norwegian antenna was used to send a message to a star system 12 light-years away.
Earlier this month, this entire company was discussed by researchers at a meeting in Paris. Douglas Vakoch, president of METI International, a San Francisco-based organization that organized the Norwegian broadcast, cited the zoo's hypothesis as a possible justification for broadcasting. If the hypothesis is correct, it is understandable why our efforts to find signals from space were unsuccessful. We have dogged our earthly cage at every turn, while the aliens are keeping their distance and on guard.
But as Vakoch argues, this one-way scenario could change. When a zoo animal suddenly barks through the bars and says, "I'm here and I think you're out there," they might answer on the other side.
Put simply, METI's intentional transmissions could lead to a discovery of cosmic society, because the shipments would tell the aliens we no longer need their helicopter parenting. We are adult enough to get in touch with each other.
However, the zoo hypothesis depends on the importance of earthly life – our existence is obviously so significant that it determines the behavior of societies that may amount to millions or billions of years. And Ball's idea requires a galaxy-sized compact that does not make any evidence of intelligent residents – radio signals, laser flashes, and even the construction of easily recognizable megastructures – invisible to earthlings. How would you do that, even if you are a highly developed alien?
Also, the idea that all aliens are interested in keeping our planet's development free and natural sounds odd, egocentric, and too altruistic. Let's be honest: The Supreme Directive was never in fashion with us. In fact, we seem to prefer the opposite: on Earth, we are constantly intervening in the cultural development of the other.
The zoo hypothesis seems to be more than a little forced. On the other hand, I have to admit that this is a cage.
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