Silence in the sky - but why?

Scientists as eminent as Stephen Hawking and Carl Sagan have long believed that humans will one day colonise the universe. But how easy would it be, why would we want to, and why haven't we seen any evidence of other life forms making their own bids for universal domination? A new paper by Dr Stuart Armstrong and Dr Anders Sandberg from Oxford University's Future of Humanity Institute (FHI) attempts to answer these questions. To be published in the August/September edition of the journal Acta Astronautica , the paper takes as its starting point the Fermi paradox - the discrepancy between the likelihood of intelligent alien life existing and the absence of observational evidence for such an existence. Dr Armstrong says: 'There are two ways of looking at our paper. The first is as a study of our future - humanity could at some point colonise the universe. The second relates to potential alien species - by showing the relative ease of crossing between galaxies, it makes the lack of evidence for other intelligent life even more puzzling. This worsens the Fermi paradox.