Grandpa Paradox

The Grandfather Paradox is a famous thought experiment in time travel theory, primarily concerning the potential contradictions that could arise from traveling back in time and changing the past. Here's a classic version of it:

Imagine a person goes back in time and kills their grandfather before the time traveler’s parent was conceived. If the grandfather dies before having children, the time traveler’s parent would never have been born, and thus the time traveler themselves would never have existed. But if the time traveler never existed, they couldn’t have traveled back in time to kill their grandfather, so the grandfather would have lived, meaning the time traveler would have been born after all, creating an inescapable logical loop or paradox.

This paradox raises questions about the consistency of time travel, causality, and whether the past can truly be changed. Various theories, like the many-worlds interpretation (where alternate realities are created) or the idea that time travel is simply impossible, are often discussed as possible resolutions to the paradox.