Scientists say it’s ridiculously unlikely that we are universe’s first intelligent culture.
A calculation gives odds of less than one in 10 billion trillion that aliens haven’t developed technology like ours.
Which means that – either now or in the past – numerous advanced civilisations must have existed on worlds besides our own.
Professor Adam Frank from the University of Rochester, who co-authored the new paper, said our experience on earth was far from unique.
“One in 10 billion trillion is incredibly small,” he said. “To me, this implies that other intelligent, technology producing species very likely have evolved before us.
“Before our result you’d be considered a pessimist if you imagined the probability of evolving a civilisation on a habitable planet were one in a trillion.
“Now even that guess implies that what’s happened here on Earth with humanity has in fact happened about a 10billion other times over cosmic history.”
Its a sum that examines the number of habitable planets in the universe and then the likelihood of civilisation arising on them.
But the new equation removes one of the big unknowns from its predecessor, how long advanced cultures will likely exist.
It also dispatches with the question of how probable it is for civilisation to arise on habitable planets.
Instead it tries to calculate how unlikely it is that we would be the only technological species ever.
So the question becomes how many alien societies have ever arisen on other worlds, instead of how many exist now.
And thanks to new data from NASA’s Kepler mission, among others, we can almost certainly say we are not the only ever advanced culture.
Professor Frank and his co-author, Professor Woodruff Sullivan, even worked out the odds of there having been another civilisation in our galaxy.
If the odds are better than one in 60billion, then there likely is or was a developed alien society in the Milky Way.
But we might never be able to contact them, because even if there have been a thousand in our galaxy, all might have collapsed already.
Professor Sullivan said: “If they live only as long as we have been around — roughly ten thousand years — then all of them are likely already extinct.
“Others won’t evolve until we are long gone. For us to have much chance of success in finding another active technological civiliaation, they must last much longer than we so far have.”