# Polchinski's paradox

> English word · Proper noun

## Definitions
1. A potential paradox serving as a comment on the Novikov self-consistency principle, in which a billiard ball, sent back in time through a wormhole, is launched at such an angle that, upon exiting the wormhole in the past, it collides with its earlier self, knocking it off course and preventing it from entering the wormhole in the first place.

## Etymology
Devised by Joseph Polchinski, American physicist.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/polchinski-s-paradox