A new explanation for the Fermi paradox links the absence of traces of other civilizations with the difficulties of moving from star to star and long waiting for a suitable trajectory.
The Milky Way may be the home of many highly developed civilizations of intelligent beings, they just visit us too rarely. This is one of the conclusions reached by the authors of a new article published in The Astronomical Journal. Its authors offered a new explanation for the famous Fermi paradox - the absence of any evidence of the existence of alien civilizations in the entire history of the Universe.
For more than half a century of discussions, several possible explanations have been proposed for the paradox: from the complete uniqueness of life on Earth to the “zoo hypothesis”, according to which more advanced creatures have been watching over us for a long time without interfering with the course of natural development. Indeed, astronomical data rather suggest that our entire Galaxy is full of worlds, one way or another suitable for life, although not always similar to ours.
But if there are enough potentially inhabited worlds, then in fact, where are their inhabitants? In their new work, British-American astrophysicist Caleb Scharf and his colleagues have found their own solution to the Fermi paradox, based on the original concept of leisurely interstellar travel.
The fact is that the stars in the Galaxy are in constant and rapid motion, sometimes approaching, then diverging. Our Sun makes a complete revolution around its center in about 230 million years and rushes at a speed of more than 200 kilometers per second. If an advanced civilization is really intelligent, then it must take into account and use this movement for interstellar travel.
Likewise, our earthly cosmonautics is guided by the orbital motion of planets and satellites. Spacecraft to Mars are sent so that the path is as short as possible, and when traveling to the distant borders of the Solar System, the gravity of the planets, past which the probe's trajectory passes, is often used. Galactic travelers can do the same.
Relying on a map of worlds suitable for habitation, they can wait for a long time to approach one of them, then make a flight and master the next "land" until the time comes to move to a new one. Worlds that are optimal for life are not exceptional, but they are rare enough that this galactic movement develops slowly over tens of millions of years. Scientists call this hypothesis "The Aurora Effect", after the fantasy novel by Kim Robinson, whose heroes make a grand interstellar journey on the "ship of generations."
The authors modeled such a process, taking into account the existing estimates of the number of worlds suitable for life, speeds, and so on. These approximate calculations showed that the Milky Way may well be full of inhabited planets and satellites, but their civilizations remain unknown and invisible to us. After all, there are about 100 billion stars in the Galaxy and many more planets, of which only about four thousand have been discovered today.
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Caleb Scharf and his co-authors even argue that a visit to Earth could have already taken place sometime in the distant past. If tens of millions of years separate us from this event, and the visit was short-lived, no trace of it could have survived. It is possible that they only looked into our system, for some reason they decided not to linger here.
Author: Sergey Vasiliev