The zoo hypothesis speculates on the behavior and presence of technologically advanced alien species, as well as the reasons why they have not made contact with Earth.
The Fermi paradox may be explained in a variety of ways, and this is one of them. The concept is that extraterrestrial life deliberately avoids communication with Earth, and one of the primary interpretations is that it does so to allow for natural evolution and social development while preventing interplanetary contamination, much like humans watching animals at a zoo.
The theory aims to explain why there is no evidence of alien life, despite the fact that its plausibility is widely recognized and hence a fair assumption of its presence.
Aliens could, for example, decide to contact humans if they have met particular technological, political, or ethical criteria. They may avoid communication until humans compel them to do so, maybe by sending a spaceship to the planets they call home.
A hesitancy to start contact might, on the other hand, show a reasonable desire to reduce danger. An extraterrestrial culture with powerful remote-sensing technology may come to the conclusion that direct contact with neighbors exposes oneself to additional hazards without providing any further benefits.
The zoo hypothesis asserts two things: first, that life will exist and evolve anytime the conditions are right, and second, that there are numerous sites where life may exist (i.e. that there are a large number of alien cultures in existence).
It’s also assumed that these extraterrestrials hold high regard for self-sustaining, spontaneous evolution and development.
If intelligence is a physical process that seeks to maximize the variety of a system’s available possibilities, a basic rationale for the zoo hypothesis would be that early contact would “unintelligently” diminish the total diversity of pathways the universe may follow.
These theories are most credible if a plurality of alien civilizations has a nearly common cultural or legal policy requiring seclusion from civilizations at Earth-like stages of development.
Random single civilizations with autonomous ideals would collide in a cosmos without a hegemonic force. This lends credence to a busy Universe with well-defined laws.
However, if there are multiple alien cultures, the uniformity of motive concept may fail, because it only takes one extraterrestrial civilization to decide to act contrary to the imperative within our detection range for it to be undone, and the likelihood of such a violation increases as the number of civilizations grows.
This idea becomes more plausible, however, if all civilizations tend to evolve similar cultural standards and values when it comes to contact, much like convergent evolution on Earth has independently evolved eyes on numerous occasions, or if all civilizations follow the lead of a particularly notable civilization, such as the first civilization among them.
The Fermi conundrum
The Fermi paradox is the seeming contradiction between the dearth of evidence for alien civilizations and extremely high estimations for its possibility, named after Italian-American scientist Enrico Fermi.
In light of this, a modified zoo hypothesis appears to be a more tempting solution to the Fermi conundrum. The temporal span between the birth of the first civilization and the rise of all future civilizations inside the Milky Way might be immense.
The first few inter-arrival durations between nascent civilizations would be equivalent in length to geologic epochs on Earth, according to a Monte Carlo simulation. What would a civilization be able to do if it had a ten-million-year, one-hundred-million-year, or half-billion-year head start?
Even if this first great civilization is long gone, their legacy may continue on in the shape of a passed-down tradition, or possibly an artificial life form committed to such a cause that does not face death.
Beyond that, it doesn’t even have to be the first civilization; it only has to be the first to propagate its philosophy and take control of a significant portion of the galaxy.
If only one civilization achieved hegemony in the distant past, it may set in motion an unbroken cycle of prohibitions against predatory colonization in favor of non-interference in subsequent civilizations. In this case, the previously described consistency of motive idea would be irrelevant.
If the oldest civilization still existing in the Milky Way has, say, a 100-million-year time advantage over the next oldest civilization, it’s possible that they’ll be in the unique position of being able to control, monitor, influence, or isolate the emergence of every civilization that comes after them within their sphere of influence.
This is similar to what happens on a daily basis on Earth within our own civilization, in that everyone born on this planet is born into a pre-existing system of familial associations, customs, traditions, and laws that have been in place for a long time before our birth and over which we have little or no control.