David Brin points to Asteroid belts at just the right place are friendly to life -November 6, 2012 , saying "This combination is calculated to be rare, in perhaps just 4% of solar systems. That rarity offers yet one more new, rather daunting candidate for the Fermi Paradox."
posted by hank on Nov 17, 2012 - 63 comments

The "Great Filter" is a hypothetical barrier to explain why civilisations are so unlikely to progress to the point of inter-stellar colonisation that we have not encountered any in 40 years of looking. Maybe humanity has already negotiated the filter - as some massive evolutionary improbability - or perhaps it lies in our future as an almost-certain threat to our existence? We should hold our breath as we look for evidence of life on Mars.
posted by rongorongo on May 12, 2008 - 85 comments