According to a new scientific study, the Milky Way may be full of alien civilizations with expansionist inflows and who have visited Earth in the past.
So far, numerous researchers have tried to respond to Fermi’s paradox . And they have done it in the most varied ways: since assuming that all intelligent life forms outside the Earth are aquatic and live in the ocean depths (and therefore do not know spaceflight), to ensure that no civilization is sustainable, and ends up destroying itself before it can dominate interstellar flights. The so-called “zoo hypothesis” has even been postulated , according to which the advanced societies of the Milky Way have decided not to contact us for the same reasons that we try not to contact, to protect them, with some indigenous populations.
But none of those solutions had taken into account, so far, that everything in the galaxy is in continuous motion. And that in the same way that the planets orbit around the stars, also the stars, with their planets in tow, orbit around the galactic center. Our Solar System, for example, completes an orbit every 230 million years.
For that reason, a study published recently in The Astronomical Journal says that if civilizations arose in very remote star systems, as with ours, which is located in a sparsely populated area of stars, near the edge of the Milky Way, it would not be a bad idea to “shorten the trip” and wait until their orbital trajectories get close enough to the new habitable worlds to allow ships and settlers to be sent.
If we could travel at the speed of light, it would take 200,000 years to pass through the disk of our galaxy.
Then, and once established in the new system, the aliens could repeat the play and wait, again, to be at an optimal travel distance to take a new leap. And so on. In such a scenario, alien civilizations would not simply launch across the galaxy but would wait long enough for their star to approach another that had a habitable planet.
“If that” enough time “were a billion years, then we would have a solution to the Fermi paradox,” explain NASA researchers and the universities of Rochester, Pennsylvania, and Columbia. That would mean that habitable worlds are so scarce that it would be necessary to wait, in fact, longer than a civilization lasts before one of them gets within reach.
In their work, the scientists used numerical models capable of simulating the propagation of civilization throughout the galaxy. For this, they took into account the most varied possibilities, from the proximity of a hypothetical civilization to the new star systems to the range and speed of their probes. At no time during the study were the intentions or the policy of expansion of these hypothetical cultures taken into account, an authentic “trap” in which other solutions to the Fermi paradox have stalled.
“We try to arrive at a model that involves the least possible number of sociological assumptions,” explains Jonathan Carroll-Nellenback, first signer of the scientific article.
Scientists calculate that in our galaxy one of every two stars has one or more planets in orbit, and that one in every 200 stars also has them within its habitability zone.
Still, a good part of the problem with the modeling of the galactic expansion of alien civilizations is that researchers could only work with a single set of data: ours. So, whether they like it or not, all their predictions are based on the patterns of our own behavior and technology —primitive from the point of view of a civilization capable of colonizing the galaxy.
However, and even with that limitation, Carroll-Nellenback and his colleagues discovered that the Milky Way could literally be full of solar systems colonized by intelligent beings, even if the most conservative estimates are applied. If they have not yet visited the Earth, says the researcher, “it is because we are not close enough.” Although they could have been in the past.
They were here?
According to the article in The Astronomical Journal, one of the main arguments against the idea that our planet may have been “visited” in the past is that there is no evidence, remainder or evidence to record that visit.
But our planet is 4.5 billion years old, and if a civilization landed here at some distant time, the traces of its stay could have been erased over time. It is even possible that aliens have passed near our world when humans already existed in it, but decided not to visit us.
The hypothesis of the ancient astronaut, not considered in the study, says that in ancient times the Earth was visited by beings from other worlds, which influenced the beginning and development of human civilization.
To think that “expansion” and “conquest” always go hand in hand is a very human tendency, and projecting it to other civilizations would be to sin of naivety. The study calls this possibility “the Aurora effect,” in honor of the novel of the same title by Kim Stanley Robinson.
In other words, alien civilizations would only settle in a fraction of the habitable worlds they encounter. And yet the number of colonized planets could be huge.
Therefore, the authors of the study do not believe that we should be discouraged by the apparent silence that surrounds us. In Carroll-Nellenback’s words, that silence “does not imply that we are alone. It simply means that habitable planets are probably very rare and difficult to reach ».
Source: Business Insider