If Drake’s formula shows an incredibly large number of existing civilizations, why haven’t they contacted us yet? This question is also known as the Fermi paradox. But the answer to it can be both simple and unsuitable: perhaps the aliens consider the Earth “boring”.
An article in The Astrophysical Journal may partially explain the Fermi paradox. An astrophysicist from the Hebrew University in Jerusalem and the author of the study, Amri Wandel, suggests that intelligent aliens may consider planets like Earth simply uninteresting. They probably have known for a long time that we have life and even an intelligent civilization, but they are more interested in those worlds where there are signs of not only biology, but also advanced technologies.
The article explores the Fermi phenomenon. Given the age of the Universe, intelligent aliens would probably have developed distant space travel long ago, and would have visited our Earth long ago. The fact that they have not yet done this may be proof that there is no other intelligent life in the Milky Way galaxy.
Where did the aliens go?
Experts have offered other explanations for the missing aliens. Perhaps they visited Earth in the past, long before humans evolved into Homo sapiens, so our planet has become uninteresting to them. Or perhaps long-distance space travel is more complicated than thought. Probably, the aliens created an advanced civilization recently in order to get to Earth. Or they deliberately decided not to study space. There was an option that they simply destroyed their civilization by self-destruction with super-powered weapons, or it could have happened due to a cataclysm, for example, a supernova explosion near their planet.
In a new article, Wandel offers an unexpected explanation: life is actually very common in the Milky Way. If there is life and advanced civilizations on many rocky planets orbiting in the habitable zone of stars, they probably simply will not spend their resources on sending signals to each star system, of which there are billions. If life is widespread, intelligent aliens are likely much more interested in signs of the presence of technology on other worlds.
The Earth has been emitting signals that can be detected from space via radio waves only since the 1930s. Theoretically, these signals have now covered about 15 thousand nearby stars and planets orbiting them. But this is a small fraction of the 400 billion stars in the Milky Way. In addition, it takes time for any return message from the aliens to get back. Therefore, a potential answer should be expected from stars that are within 50 light-years.
But the way radio signals communicate is not very reliable. The oldest radio signals of the Earth, unintentionally broadcast into space, have already become so distorted after about one light-year that aliens will not be able to recognize them. Therefore, it is quite possible that Earth’s signals will not reach another form of intelligent life. However, over time and as our planet emits more and more high-quality radio broadcasting, it is likely that Earth’s technological signals will find smart listeners.
The data obtained indicate that there are probably no intelligent civilizations within a radius of 50 light-years from our planet. But intelligent life may still be out there somewhere — they’re just waiting for our call.
Earlier we reported that scientists were afraid to reveal the truth about extraterrestrials to humanity.
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