Alien life may well be plentiful in the universe, but we will probably have to wait another 1,500 years before we make contact with it, an astronomer has claimed. By combining the Fermi Paradox with the Mediocrity Principle, Evan Solomonides has come up with a new equation for the time at which we can expect to start hearing from extraterrestrial civilisations.

The Fermi Paradox relates to the lack of evidence of alien life elsewhere in the universe. There are estimated to be billions of potentially habitable Earth-like planets in the universe, meaning there is a good chance intelligent life has evolved on some of them. So if life is abundant in the universe, why have we found no evidence of it? Enrico Fermi, after who the paradox is named, said the lack of alien contact indicates there are no advanced extraterrestrials anywhere else in the galaxy.

The Mediocrity Principle, on the other hand, says we (intelligent life on Earth) are nothing special. It says there is nothing unusual about the evolution of our Solar System, the Earth and human life, so we should assume there are other civilisations out there that have developed intelligence. However, it also means aliens will not discover us for some time.

Solomonides, a student at Cornell University, will present his findings at the American Astronomical Society's meeting in San Diego. "We haven't heard from aliens yet, as space is a big place – but that doesn't mean no one is out there," he said.


The search for extraterrestrials involves sending out signals. For example, TV and radio broadcasts are sent out into space as a by-product of broadcasting. As they travel from Earth at the speed of light, these signals could end up being picked up by aliens on planets they pass. However, said aliens would then need to decipher them – turning light waves into sound then translating the language transmitted into one they could understand.

So far, our signals have travelled 80 light years and have reached an estimated 3,555 Earth-like planets. After combining the two equations, Solomonides and co-author Yervant Terzian found we may hear from an alien civilisation at the point when around half of the Milky Way has received our signals – in about 1,500 years.

"It's possible to hear any time at all, but it becomes likely we will have heard around 1,500 years from now," said Solomonides. "This is not to say that we must be reached by then or else we are, in fact, alone. We simply claim that it is somewhat unlikely that we will not hear anything before that time. Until then, it is possible that we appear to be alone – even if we are not. But if we stop listening or looking, we may miss the signals. So we should keep looking."