Sylvia Fontis at Luna University has built a working time machine—she calls it the Dimensional Revolver—but she’s too scared to use it until Professor Kent comes up with an idea for an experiment.
So what did you do, bring back the results of the Centauri Probe? Kill your grandmother?

Variants

(1)
  1. “Stretch of Time” by Ruth Berman, in Analog, October 1972.
  2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . written by Ruth Berman