Many key events in the history of humankind show evidence of having been intended by human beings from the future, who took specific actions that would steer the world in a particular direction. This 'intervention' theory is based on sound mathematical and scientific arguments, consistent with Einstein's demonstration of the possibility of time travel. Time travellers - some of them anonymous, some celebrated in history - have made alterations to our planetary and global environment (the creation of the Moon, the extinction of the dinosaurs) that were necessary to allow us to exist and to develop as an intelligent species.展开