Two stories can use a time machine and yet obey incompatible rules. The comparator shows what can change, how memory is preserved, and what paradoxes each model produces.
Choose up to three works
Consistency values internal rules; science, its relationship with recognizable phenomena or theories.
The great narrative models of time travel
Single and immutable line
Every trip to the past was already part of history. The traveler can cause events, but not create a contradiction. It is the terrain of self-consistent loops and the Novikov conjecture.
Modifiable single line
The traveler's actions rewrite his own past. This model produces very intuitive images—photographs that change, memories that are erased—but it must answer what happens to the original cause of the trip.
Branching and parallel universes
Changing the past opens a new branch. The line of origin may continue to exist and the traveler does not necessarily erase his birth. It is a common narrative solution to the grandfather paradox, although it is not a physical demonstration that we can move between branches.
Bucle causal
A person, object, or information returns to the past and becomes its own cause. The story can be consistent and, at the same time, leave open the question of the origin of the information.
Relativity and inversion
Time dilation allows us to move towards the future comparatively without returning to the past. The entropy reversal of Tenet, on the other hand, is a specific fictional rule that should not be confused with relativity.
How to interpret scores
Narrative consistency assesses whether the work applies its own rules in a stable manner. The scientific basis indicates how much it relies on measured phenomena or recognizable physical theories. A low science score doesn't mean history is bad.; it only indicates that its mechanism belongs mainly to fiction.