tidsparadox

A tidsparadox, or time paradox, refers to a contradiction or seemingly impossible situation that arises when conditions created by time travel threaten to negate the traveler's actions or the initial conditions that enabled the time travel in the first place. The term is widely used in philosophy of time and in physics discussions of closed timelike curves and causality.

Common forms include the grandfather paradox: going back in time to prevent one’s own existence; the bootstrap paradox: information or objects sent back in time without a clear origin; and predestination paradox: actions in the past ensure the future occurs. In each case, inconsistent causal loops challenge intuitive notions of chronology.

In physics, some theories allow time travel within general relativity via closed timelike curves, though no experimental evidence exists. Proposals to resolve paradoxes include the Novikov self-consistency principle, which forbids paradoxical outcomes; the many-worlds interpretation, which preserves consistency by branching timelines; and Hawking's chronology protection conjecture, which posits physical laws prevent macroscopic CTCs. Quantum approaches sometimes invoke decoherence or quantum superpositions to mitigate paradoxes.

In fiction, tidsparadox is a staple device used to explore causality, free will, and fate. Authors and filmmakers often choose between self-consistent timelines, parallel universes, or explicit paradoxes as plot devices. The term thus denotes both a methodological concern in theoretical physics and a narrative motif in science fiction.