Physicist Robert L. Forward builds a reversing machine.
This is a bad story ending in a bad pun—and I mean a bad pun, not a pun that makes you groan and wish you had said it yourself, but a pun that just falls there, thud, on the ground and stares up at you mournfully. Do not read this story.
Robert L. Forward, by the way, is a real physicist who really worked for Hughes, although I don’t know that he ever demonstrated a machine such as the story describes to Asimov. This story—or, its first two-thirds, anyway—was used in a contest. The contestants were to prove an alternate ending. The winner of the contest was published in Analog as “Left to Right, and Beyond.”