• Beliriel@lemmy.world
    31·
    2 years ago

    There’s really only 2 not 5. Most are just variants of the two:

    1. Singleton universe: time is linear, causality is set in stone, either through fix points (events that can’t be changed). Time travel will just create a loop but causality dictates that this will already have happened and you can’t change events.
    2. Multiverse: You can go back in time, but doing so will branch the timeline and create a different universe. This will not have impact on any causality as you’re an anomaly and you can do whatever you want (kill your grandpa, have a relationship with yourself etc.) and nothing will happen because you are in a parallel dimension and effectively can’t produce paradoxes.

    Sometimes movies just ignore paradoxes or logical fallacies because it makes for better screen time. But really all time travel is one of the two.

    Primer is 1.
    MCU is 2. (Endgame pretends to be 1 but really with the series Loki it’s clear it’s 2)
    Predestination is 1.
    The series Dark is actually a weird mix of the two. First it’s 1. And then morphs into 2.
    Triangle is 1.
    Rick and Morty is 2.

    • Hup!@lemmy.world
      1·
      2 years ago

      There is also type 3, called a closed timelike curve or Lorenzian manifold. Aka a Djinn: a loop in causality where the original cause depends on the final effect. It exists outside of linear time and yet is not a separate timeline or “-verse” in the multiverse.

        • Hup!@lemmy.world
          1·
          2 years ago

          A singleton universe doesn’t allow for multiple versions of a single moment to coexist. A closed timelike curve does, and potentially an infinite number of variations all as long as they are continuous in the same curve. It’s also different from a proper many worlds theory with quantum variations. The relationship between causes and effects are mapped differently. Thus it’s its own thing.