If aliens ever contact us, it will be perhaps the single most significant event in human history. And Paul Davies will be responsible for saying something back. For fifty years, the Search for Extra-Terrestrial Intelligence has been scanning the skies. Now Davies, head of SETI"s Post Detection Task Group, with "a rare talent for making physics mind-bogglingly vivid and exciting" (Times Higher Education), explores what the mysterious silence it has so far encountered could mean. Here, he looks at exciting new ways to make contact with extra-terrestrial life. He considers what form advanced alien intelligence is likely to take if it exists. And perhaps more importantly, what exactly it would mean if it didn"t - how extraordinary it would be if we were alone, to be human and here in this staggering, eerie silence...