Relativistic Interstellar Trade

Time dilation as usually encountered in sf, e.g., in Poul Anderson's Tau Zero, requires time-consuming acceleration at the beginning of an interstellar journey and deceleration at the other end whereas, in Anderson's Starfarers (New York, 1999), the zero-zero drive can jump instantly from normal velocity to near light speed and back down again, thus giving explorers and traders the maximum benefit of time dilation. In the Kith ship Fleetwing:

"'Ninety-seven light-years took us eight zero-zero months.'" (p. 127)

- although the outward bound Envoy is much faster because its engine has a bigger "'...quantum gate...'" (p. 126).

(I have yet to reread the passage explaining the technicalities of the zero-zero drive.)

Fleetwing visits the outermost extrasolar colony, on the planet Aerie, for a change from the Quadrangle Trade where its crew had sold:

biochemicals from the seas of an uninhabitable planet;
rare isotopes from another planetary system;
arts and crafts from Feng Huang;
Terrestrial biostock.

On Aerie, they trade and also make a documentary to sell among the heart stars. The Kith speak Kithic whereas Xyrese is spoken widely among the heart stars. On Aerie, government is by town meetings scattered across the occupied continent but the Magistrate from his castle provides militia and a teleconference court of appeal.

The wonders of Poul Anderson's imagined universes are endless.