Arwen Nicholson and Duncan Forgan of the University of Edinburgh (UK) used computer simulations to prove that if representatives of e̳x̳t̳r̳a̳t̳e̳r̳r̳e̳s̳t̳r̳i̳a̳l̳ c̳i̳v̳i̳l̳i̳z̳a̳t̳i̳o̳n̳s̳ were able to travel from one planet to another, they would fly across our entire galaxy in a relatively short period of time and visit our planet.
Voyager 1 spacecraft was able to move away from the Earth at a distance of less than one light day in 36 years of its mission. However, according to Nicholson and Forgan, it takes an a̳l̳i̳e̳n̳ spaceship only ten million years to explore the whole Milky Way.
The ship would need to travel at the speed of one-tenth the speed of light, if accelerated due to the gravitational field of stars. During the 1960s, a theory appeared about “smart” space probes capable of replicating themselves.
American astronomer Ronald Bracewell believed that mankind should do its best to invent such probes, rather than catch radio signals of artificial origin, as suggested by SETI program. In 1949, John von Neumann developed a mathematical model of the device that was cloning itself.
According to current calculations made by Nicholson and Forgan, there are three possible scenarios for such probes to operate. This includes flying with running engines, the use of gravitational acceleration and, finally, “jumping” from star to star.
Even the Voyager is capable of “bouncing” from gravitational fields of the solar system. Thus, green a̳l̳i̳e̳n̳s are unlikely to be found on Earth, the scientists believe. If a̳l̳i̳e̳n̳s ever visited our planet, it was robotic vehicles, rather than living creatures.
Famous science fiction writer Arthur C. Clarke gives a description of such visits in his novel “Rendezvous with Rama.” In the book, a group of terrestrial astronauts gets inside a giant cylinder stuffed with electronic equipment, approaching the Sun.
Nicholson and Forgan believe that a̳l̳i̳e̳n̳ probes are able to run their own course. They scan the planets of star systems, searching for signs of life there, and create their own copies, which, in turn, search for new stars.
To crown it all, it is quite possible that such probes are created by several highly-developed e̳x̳t̳r̳a̳t̳e̳r̳r̳e̳s̳t̳r̳i̳a̳l̳ c̳i̳v̳i̳l̳i̳z̳a̳t̳i̳o̳n̳s̳. It is also possible that some clone ships may attack other ships as a result of technical failures and destroy them. In any case, such stories can be found in science fiction literature.
One can also assume that such ships communicate with each other to carry out their tasks more efficiently – not to explore one and the same object repeatedly, for instance.
However, we should not delude ourselves about the contacts of a̳l̳i̳e̳n̳ robots with earthlings. It is possible that a̳l̳i̳e̳n̳ probes are equipped with special systems to determine the level of intelligence of the living creatures within range of their activities.
A̳l̳i̳e̳n̳s are not interested in establishing communication with intelligent beings. The purpose of robotic devices is the collection of information about the planets, not making contact. Moreover, in all probability, a̳l̳i̳e̳n̳ space vehicles are programmed to attract as little attention as possible.
There is no reliable information, for the time being, to prove that U̳F̳O̳s, or flying saucers, are vessels from other c̳i̳v̳i̳l̳i̳z̳a̳t̳i̳o̳n̳s̳. One can only build theories, like Nicholson and Forgan do, and wait for brothers in mind, if they do exist, to show themselves to us.