A breeze of pollen from intelligent alien vegetation continually blows into one artificial wormhole and out another eleven years earlier, which gets Major Okonkwo’s government het up about using it to repeatedly send back research results while Okonkwo and her team try to figure out how and where the rival government is spying on things and why the pollen stream has stopped. All the while, there are discussions of how careful everyone must be to avoid grandfather paradoxes.

For me, Künsken’s earlier novella of aliens and time dilation (“Schools of Clay”) was a realistic, character-driven, multi-layered story worthy of a Hugo, but this second novella was less engaging, even though it does involve actual time travel.
On their way, the Force had discovered the time gates, a pair of artificial wormholes connected across eleven years of time. All the ancient wormholes were incalcuably valuable; their possession was the defining feature of the patron nations. Finding a wormhole was the Union’s chance to slip from beneath the yoke of the Congregate.

Variants

(1)
  1. “Pollen from a Future Harvest” by Derek Künsken, in Asimov’s Science Fiction, July 2015.
    2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . written by Derek Künsken