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.

In a mind-bending story with vast ideas on every page bang, the artificial intelligence Ulixes-316 starts as a financial agent for a galaxy-spanning bank in which he and Poluphemos witness (or cause?) an explosion that sets off a wavefront that’s collapsing space time at an ever expanding rate. With this as background, time travel plays both a minor role in a light-years-wide tachyon-based computing network and the key role in how a degenerating Ulixes can take care of his damaged companion Poluphemos and take an ethically questionable step that involves rewriting the Big Bang.