What If—

"What If—" is a fantasy short story by Isaac Asimov that was first published in the Summer 1952 issue of Fantastic and reprinted in the 1969 collection Nightfall and Other Stories. The story was inspired by the author's wife, who challenged him to produce a story based on a train trip they were taking to New York.

Plot

A married couple are travelling on a train from Boston, Massachusetts to New York City. They meet a mysterious silent man known only as Mr. If (his first name is implied to be What, but whether this is true or not is left to the reader), who shows them a small portable television-like device about six by nine inches in size (which is conceivably the first laptop).

On the screen, he shows them scenes from their earlier lives and what might have happened if certain minor but pivotal events had not occurred.

Background

The theme of major events being altered by relatively minor changes would recur in Asimov's 1955 novel The End of Eternity and his 1958 short story "Spell My Name with an S".

The story's theme and idea has been used in two episodes of Futurama: "Anthology of Interest" and "Anthology of Interest II". with a 'What If—' machine similar to Mr. If's. A similar idea has also occurred in a revived series Series Four episode of Doctor Who: "Turn Left".