A researcher has claimed that there may be four extraterrestrial civilisations in the Milky Way that could attack or invade the planet Earth. As reported by Vice News, Alberto Caballero, who is a PhD student at the University of Vigo in Spain, estimated the prevalence of "malicious extraterrestrial" civilisations.
According to Mr. Caballero, the Big Ear telescope at Ohio State University received a burst of radio waves that lasted a minute and 12 seconds. The signal contained an alphanumeric code and it was dubbed the "WoW Signal". It is considered the best candidate signal of extraterrestrial life since humans began searching more than 60 years ago.
In his paper - titled "Estimating the Prevalence of Malicious Extraterrestrial Civilizations"- Mr. Caballero claimed that he had pinpointed the exact source of this signal. He believes that it originated from a Sun-like star 1,800 lightyears from the Earth.
However, he said that the research is considered to be more of a "thought experiment" and said that the aim of his paper is to warn other scientists and put a number to the civilizations that could possibly revert to the messages we send out.
He warned scientists to use caution in using the practice of Messaging Extraterrestrial Intelligence (METI) for fear it could provoke an alien invasion.
However, as per The New York Post, the researcher also concluded that the odds of extraterrestrials wiping out the human species is about the same as the Earth being hit by a "planet-killer asteroid". In his paper, Mr Caballero wrote that such an event takes place once every 100 million years, so humans are in all likelihood safe for the time being.
He also stated that there is likely fewer than one malicious extraterrestrial civilization in the Milky Way that has also mastered interstellar travel. Further, the researcher said that as societies advance, they are less likely to engage in conflict, suggesting to him that an alien force will also follow the same behavior as they progress technologically.
Mr. Caballero hopes that his research will help start a conversation about whether it is actually risky to send messages into space.