‘Footprints of alien technology’, by Paul Davies | Space Archaeology

Review: ‘Footprints of alien technology’, by Paul Davies | Space Archaeology: "Since the search for extraterrestrial intelligence began, astronomers have been trying to answer the question “Are we alone in the universe?” in two ways: by listening for deliberate messages, and by looking for physical evidence – the products and byproducts – arising as a consequence of extraterrestrial civilization."