Forgetfulness

Millions of years after mankind raised various species and sent them to the stars, one of the species returns and believes that humans have fallen into a primitive existence. And the time travel? Partway through the story, there’s a power source that goes to the end of time and cycles back to the beginning of time. In addition, Fred Galvin pointed out to me that even though it takes the aliens six years to travel to Earth, when they return to their home planet, only one year has passed, apparently a complete undoing by Seun of Rhth of the alien invasion.

The story also appeared in Healy and McComas’s seminal anthology, Adventures in Time and Space, and it was made into a one-act play in 1943 by Wayne Gordon.