In this fascinating volume one of the greatest imaginative mind in the world of science fiction turns his attention to science fact. far from the drabness of scientific textbooks, here is a mind-bending trip into the world as it is - and as it might have been. What would life on Earth be like if we didn't have a Moon? Why don't we follow the clear logic of a seasonal calendar? Must we computerize the world because we have grown too lazy to run it in any other way? Scientist or non-scientist,layman or specialist, Asimov invites you to join him on a trip back into the past - and forward into the future.