We’ve been looking up at the Milky Way for thousands of years, wondering if there was someone out there looking at us from a planet a long way away.
Now, a study carried out at Nottingham University has calculated that there may be over thirty intelligent civilizations in our galaxy, on planets similar to the Earth, but we would need to survive for another 6,120 years in order to communicate with them.
The paper, published in the Astrophysics Journal, uses a theory known as The Astrobiological Copernican Limit which assumes that life develops in the same way that it has done on Earth.
The work carried out in Nottingham builds on a theoretical calculation thought up in the 1960s by Francis Drake. The original Drake equation makes some pretty large assumptions and then multiplies them together so any results have to be taken with a light-year sized pinch of salt.
A key factor is finding stars with a chemical make-up similar to our own sun – Tom Westby, one of the paper’s authors, explained that civilizations like ours would need a sun with high metal content to support life.
The Earth took 4.5 billion years to develop to the point it has done, but the technological world only started in the mid-1890s when Marconi transmitted the first radio signals – 125 years ago. If we could find how long the other civilizations in our galaxy had been using technology, we could calculate how long life on Earth may last.
So scientists are busy searching for signals from space that would indicate technologically advanced civilizations – if there are a lot of them, that suggests that we may have a long time left; if there are only a few, it may mean that our days are numbered.