Sliding scale of the expense and time needed for interstellar travel.
- 0: Interstellar travel doesn't exist in this setting, even of the slower-than-light variety.
- 1: Interstellar travel does exists but takes centuries or millennia. Journeys requie a generation ship, stasis for the crew or some other workaround.
- 2: Interstellar travel takes years or decades, but passengers can make the journey within their lifetimess. Generation ships and/or stasis, might, again, come into play here.
- 3: Interstellar travel takes months or days to get from one star to another.
- 4: Interstellar travel takes a few minutes or hours and typically involves “hyperspace”- or “warp drive”-type contrivances. This makes travel between systems much like driving between locations in present time.
- 5: Interstellar travel can be done in seconds or less by starship or even by means of a gateway or teleportation. (This option does not occur often in fiction, at lest for “mortal” beings.)
