PREFACE

But the point I wish to make is that we can now calculate many thousands of times as fast as we could in 1953 and at least a million times as fast as we could three hundred years ago. Now this change is quite extraordinary, if one compares it for example with the increase in the speed of travel. A satellite orbiting the earth or moving towards the planets is unlikely to go much faster than twenty-five or thirty thousand miles an hour. An ordinary man can usually do two and a half or three, so that the satellite is perhaps ten thousand times as fast as a walking man. The enormous increase in speed of travel has changed our world and our ideas of the potentially possible. We don't use satellites to go from Manchester to Edinburgh in a few minutes, but we hope to explore the solar system.