The Unexpected

Every time a space traveler lands on a new planet or every time a time traveler arrives in a new future period, anything can happen. The author is free to create something entirely new on his blank sheet of paper or blank computer screen. In Poul Anderson's The Boat Of A Million Years, the Survivors could have survived into an old-style sf future with hyperdrive and multiple alien species. They might even have survived into Anderson's Technic History. But this would have seemed inappropriate, especially since to us it would have been old. After that long historical build-up, we expected, and received, a more plausible-seeming extrapolation from then current knowledge. Slower than light interstellar travel and less easily found aliens fitted such a picture.

We would like to read a novel set in a rendezvous station or one set a million years later when the Survivors reconvene, having wandered the galaxy. But the latter was impossible. Few, if any, of the eight would survive for another million years. And they would surely be changed utterly. They might have spent time in environments that would change their physical appearance. They would even have trouble remembering anything from a million years previously. To remember anything, we have to think about it sometimes and how often would they be able to think about any particular experience out of so many?

A man who had changed psychologically and who never remembered or thought about having been Hanno would hardly be Hanno any more  - although spatiotemporal continuity does remain the criterion of personal identity.

Will lifespans be extended in future and, if so, for how long? People living then will find that their ancestors have speculated about it.