Interesting. (Sorry, Spock.) I offer the following conjectures -- because they lack the falsifiability for them to rise to the level of hypotheses. 1) Causalit

Interesting. (Sorry, Spock.) I offer the following conjectures -- because they lack the falsifiability for them to rise to the level of hypotheses. 1) Causality may resemble inertia -- that is, what we observe as cause-and-effect only seems that way because we haven't observed an analogue to Newton's "Outside Force." So causality might not be an iron law. (In the paper, we introduce two constraints: remains and appears.) 2) If quantum mechanics can handle infinite universes, presumably distinct in space but not time, then maybe it could handle infinite universes in time. So a time traveler might not be in his original universe, but one equal to his original +/- delta T. 3) Whatever mechanism allows for time travel probably breaks causality, which means a time traveler killing their ancestor would not cause the time traveler to disappear. (The paper refers to this as metaphysical model T2 – every time a person goes back in time a new copy (clone) is generated, and multiple clones may coexist in time)