Look up at the stars and ask yourself: what scares me more ? To be alone in the Universe, or to know that there is someone else up there? An age-old question, as valid for you and me as it was for Giordano Bruno when he wrote about an “infinity of worlds” before being burnt at the stake in 1600.  But fifty years ago to the day, a letter to Nature ended the passive, look-up-and-ponder attitude by proposing a scientific, experimental approach.  We don’t have an answer yet (or you and I would know), but in the process we have come up with quite a tale to tell.