[jbcohen]

I have always thought that there are four types of sci-fi books. Past - where someone from our time frame goes to earth's past for example TV's Land of the Lost; Present - where some one from the future or the past arrives in our time frame (I do not have an example of this); future - someone from our time frame goes to the future or someone from our past goes to the future (the classic novel the time machine is a good example here); and future/future - when someone from our future moves around within our future - star treck does this all the time. Can you come up with additional examples of each? What is your critique of my analysis.