grandfather paradox

American  

[grand-fah-ther par-uh-doks, gran-] / ˈgrændˌfɑ ðər ˌpær ə dɒks, ˈgræn- /

noun

1. (in science fiction) a paradox created by time travel in which a person travels back in time and changes something in their own past or the past of their own timeline, after which the resulting timeline is altered such that the future point from which the time travel began does not exist or is unrecognizable.

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Etymology

Origin of grandfather paradox

First recorded in 1970–75

Example Sentences

This is how the grandfather paradox was first explained to me: Imagine a boy whose grandfather invented a time machine.

From Los Angeles Times

Discussion of the butterfly effect, the grandfather paradox, or big balls of wibbly wobbly, timey wimey stuff are scarce.

From Salon

Part of his reasoning involved the paradoxes time travel would create such as the aforementioned situation with a billiard ball and its more famous counterpart, the grandfather paradox: If you go back in time and kill your grandfather before he has children, you can’t be born, and therefore you can’t time travel, and therefore you couldn’t have killed your grandfather.

From Scientific American

Add a few flying saucer chases, cook up a quickie solution to the grandfather paradox and this movie might have fallen at the intersection of “E.T.” and “Back to the Future.”

From New York Times

The most famous of these conundrums is the so-called “grandfather paradox.”

From National Geographic