Time for some trolling. xD
Definitely doing that for Harry Potter books lol, fuck that author (she who shall not be named).
Best let them come up with the idea, then you publish it the next day, and watch the author’s reaction:
“Someone has already published a book on the same idea? Nooo wayyy!”
[Insert “U Mad Bro” Trollface Meme]
For those that want to know the science of this, just watch one of the Stephen Hawkin’s shows. In short, matter can’t be created nor destroyed, but the moment you go back in time you have added matter to this timeline, thus creating matter out of nothing since the particles that make you up are already in that timeline, even if in another form.