, who died at the age of 43, famously laid out some time travel rules for Marvel Comics creators, that were used pretty much as originally planned inMark Gruenwald's Rules Of Time Travel
1. The Marvel Universe is part of a multiverse which diverge from one another at critical junctures. 4. If one travels a second time to an era one has already been to, one will not materialize on the 'virgin' timeline nor the timeline diverged by one's previous trip, but a third timeline diverged from one or the other. A time traveler can never travel back to the exact same timeline more than once. Again, since the second and third divergent timelines are identical until the time traveler's arrival, they will be indistinguishable at first.
7. Altering an incident in the past will indeed affect the future reality of the timeline diverged by the time traveler's presence. One can create any number of different divergencies by one's significant actions, the act of time travel being but the first. Whether one will be able to return to the present of the timeline where one did no reality-tampering divergences or one which diverged as a consequence of one's past actions is a function of the means of time travel.
10. There are three possible methods of time travel in the Marvel Universe: a. Time travel machines . b. Magic . c. Personally generated energy .