Physicist Enrico Fermi, during a discussion about the possibility of alien life, asked a very important question: “Where is everybody?” This is now known as the Fermi Paradox; if the universe is so big and so full of the right stars and planets, why haven’t we met any other civilizations yet?
Humans have been sending broadcasts into space for about 80 years, reaching about 8,500 stars and 3,500 Earth-like planets. This is a tiny fraction considering the Milky Way has more than 200 billion stars, and American researchers think this to be an indication that the Fermi Paradox is not a paradox at all.
Cornell student Evan Solomonides and his professor Yervant Terzian have worked out how long the average advanced civilization should take to make contact with another one. Based on purely statistical arguments, as well as the Drake equation and the Mediocrity Principle (humans and Earth are not special), they estimate that it takes about 1,600 years of broadcasting to make alien contact in the Milky Way.
“We haven’t heard from aliens yet, as space is a big place – but that doesn’t mean no one is out there,” said Solomonides in a statement.
“It’s possible to hear any time at all, but it becomes likely we will have heard around 1,500 years from now. 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.”
The research also suggests that there have been less than 210 intelligent communicating civilizations in galactic history. Solominides will present all these findings at the American Astronomical Society’s meeting on June 16 in San Diego, and a pre-print paper with the results is available online.
The analysis relays heavily on the Mediocrity Principle, an important philosophical notion that tells us that we should always assume that events that might seem unique or rare (like life on Earth, the evolution of the Solar System, and so on) are not so.
“We are on the third planet around a tediously boring star surrounded by other completely normal stars about two-thirds of the way along one of the several arms of a remarkably average spiral galaxy,” said Solominides.
“The Mediocrity Principle is the idea that because we are not in any special location in the universe, we should not be anything special in the universe.”
When we apply the Mediocrity principle to Fermi’s question, then it shouldn’t even be considered a paradox. We are a surprisingly young civilization, so it is perfectly reasonable to appear to be alone. Although, if in 1,500 years we have not met anyone, then we can start reassessing our place in the cosmos.