isoisäparadoksin

The isoisäparadoksi, or grandfather paradox, is a thought experiment concerning time travel. It explores the logical inconsistencies that arise if one were to travel to the past and alter an event that would prevent their own existence.

The paradox is typically illustrated by the scenario of a person traveling back in time to prevent their grandfather from meeting their grandmother. If successful, the time traveler's parent would never be born, and consequently, the time traveler themselves would never be born. This creates a causal loop: if the time traveler was never born, they could not have traveled back in time to prevent their grandparents from meeting, meaning they would have been born after all, allowing them to travel back in time, and so on.

Various theoretical resolutions have been proposed for the grandfather paradox. One common idea is the concept of a self-healing timeline, where any attempt to alter the past is either unsuccessful or leads to the same outcome through a different sequence of events. Another possibility is the existence of parallel universes or alternate timelines, where the time traveler's actions create a new timeline in which they are never born, but their original timeline remains unaffected. Some theories suggest that the very nature of time travel might prevent such paradoxes from occurring, perhaps by imposing physical limitations or by making it impossible to interact with the past in a way that would create a contradiction. The isoisäparadoksi remains a staple in discussions of theoretical physics and science fiction.