Sunday, 29 January 2017
A fellow sf reader once suggested to me that a good sequel says, "Now there is a hell of a lot that we didn't tell you before!" A good sequel can do this but should nevertheless remain aesthetically congruous with the previous volume. I think that it would be inappropriate to introduce causality violation in a sequel to The Time Machine or newly discovered faster than light interstellar travel in a sequel to any of Poul Anderson's works that are based on the premise of STL travel.
However, a future history, reflecting real history, can show technological advances. Thus, Heinlein's Future History, Anderson's Psychotechnic History and Niven's Known Space History all show an STL period followed by an FTL period. Comparing future histories is one really enjoyable aspect of reading sf.