Sadly, those are the best sites I could find with references to the ontological paradox (also called the bootstrap paradox).
In one version of this paradox, you have an object which has no beginning and no end (a bit like a mobius strip). The pocket watch in Somewhere in Time is an ontological paradox. Elise gives it to Richard, telling him to come back to her. He does, and then leaves the watch with her, which is how she comes to have the watch to give to him. In Star Trek II: The Wrath of Khan, McCoy gives Kirk a pair of glasses. In Star Trek IV: The Voyage Home, Kirk sells the glasses at an antique store, saying “they will be again, that’s the beauty of it” when Spock points out that they were a gift.
Just to forewarn everyone – I use this kind of thing. A LOT. 🙂 I like a good paradox. Ontological, grandfather, reverse grandfather – bringing future knowledge to the past is great for setting up alternate timelines. I once had a friend freak out that I was breaking all sorts of rules of time travel. It’s fiction. In Star Trek, Scotty created transparent aluminum in the 80s, and the world did not self-destruct.
I was going to write that I like the lighthearted time travel books and shows better than anything more serious, but the only thing I could think of for a “serious” example was Somewhere in Time. So, I found this list of 50 time travel movies… and I realized that it would have been a lie. While Bill & Ted, Groundhog Day, and Star Trek IV are great movies and have influenced my thinking (although I like the Supernatural episode “Mystery Spot” more than the movie Groundhog Day – in fact, I think I have only seen the movie once, but have watched “Mystery Spot” half a dozen times), my favorite movies on this list are The Butterfly Effect, 12 Monkeys, and the Terminator movies (mainly the first two in the series). Not exactly lighthearted movies. I always loved Planet of the Apes, too. Never really thought of it as time travel when I was a kid, though.
The movie list has an “unresolved paradox” section with each movie. Everybody loves a good paradox. 🙂
I think I’ll spend the weekend curled up with a bunch of time travel movies and lose track of… time.