The Grandfather Paradox is a thought experiment that questions the consistency of the timeline. Imagine a time traveler who goes back in time and kills the grandfather of a person who was born after the event. This would mean the person was never born. But if they were never born, then how could the time traveler have gone back in time to kill the grandfather in the first place?
This paradox raises questions about free will and the nature of causality. Is it possible for events to have consequences that undo themselves?
See more paradoxes Quantum Mechanics