Video by Craig Flaster
There are many time travel movies, but very few actually agree on what the rules of the space-time continuum are. Can you change the past and therefore the future? Or did what happened always happen?
The new movie "Edge of Tomorrow," for example, takes several notes from the "Groundhog Day" school of time travel. Tom Cruise's character is stuck in a seemingly endless one-day loop, but he retains all of his memories.
To help clarify the tricky ins and outs of temporal displacement, here's a handy chart that should keep things straight, no matter which movie you're discussing.
And just to further prove how confusing the breadth of movie time travel is, you can watch characters explain it to each other.
"Edge of Tomorrow" opens in theaters on June 6.