STL Or FTL

We, or at least I, think of interstellar future histories as either FTL, e.g., Poul Anderson's Psychotechnic and Technic Histories, or STL, e.g., Anderson's Maurai, Flying Mountains, Rustum, Kith, Harvest Of Stars and Genesis histories or Larry Niven's Leshy Circuit series.

(The mostly Earth-bound Maurai History goes interstellar in the time travel novel, There Will Be Time.)

However, some future histories have an STL period followed by an FTL period:

Robert Heinlein's Future History has generation ships, then Libby's FTL drive;

the Psychotechnic History has a generation ship, then the hyperdrive;

in Larry Niven's Known Space History, the Thrintun had FTL but the Pak did not;

also in Known Space, the early Man-Kzin Wars were fought at sub-light speeds but men won decisively when they had acquired the hyperdrive.

In an STL period or history, interstellar journeys last for objective decades or centuries but the travelers benefit from time dilation which alters perceptions of aging and of social change.

Two kinds of -

- imaginative fiction: fantasy and sf;
- sf: hard and soft;
- future history: British and American;
- interstellar travel: STL and FTL;
- time travel: circular causality and causality violation.