Ever since the beginning of our space-faring age scientists have wondered about the likelihood that intelligent life could be found on planets outside our Solar System. At present there are no indications in our cosmic neighbourhood that there are any exocivilisations on exoplanets. The Italian-American physicist Enrico Fermi (1901–1954) was among those wondering about why we have no evidence of any life beyond our Solar System. He considered this with some astronomer colleagues in 1950, and after that this situation came to be known as the ‘Fermi paradox’1 and is still discussed widely.