`It ranks among the most enduring mysteries of the cosmos. Physicists call it the Fermi paradox after the Italian Nobel laureate Enrico Fermi, who, in 1950, pointed out the glaring conflict between predictions that life was elsewhere in the universe – and the conspicuous lack of aliens who have come to visit.
Now a Danish researcher believes he may have solved the paradox. Extra-terrestrials have yet to find us because they haven’t had enough time to look. [..]
He found that even if the alien ships could hurtle through space at a tenth of the speed of light, or 30,000km a second, – Nasa’s current Cassini mission to Saturn is plodding along at 32km a second – it would take 10bn years, roughly half the age of the universe, to explore just 4% of the galaxy.’