This is a complicated one. There is fate, which says that certain characters will do certain things, but external forces can be reacted to. There is history, that controls major events and doesn't like to be messed with, but ignores the content of conversation... Screw it, I don't even understand it and I'm turning the rules on their ear anyway. The big question is Does it count as a circular answer if a character says "You should go ask X, he'll be Y today." The circular answer being that a time traveler handed someone the answer to a question that he actually had to work out. (You hand your math homework to yourself in the past to copy.... where do the answers come from?) I guess a better example is that you do a speech in front of the class, someone compares it to X book, and you go into the past and suggest that someone check in X book.
I believe logic goes out the window when dealing with time travel and such complexities; probably best to rely on your own imagination to settle out questions. I mean going back in time is not a linear event, what with the theoretical existence of different dimensions and branes of reality, one could be branching into a totality different time frame, or one that is indiscernible from your own, but with a particular difference that you could never find.
If I had a pocket watch my dad gave me, and I go back in time to give him the pocket watch when he was a kid, where did the watch come from? I'm guessing that this is what you want to know. The answer is that it came from nowhere. It's a paradox. The watch is in an infinite time loop, and therefor must be infinitely old--or at least as old as time itself. I would stay away from writing objects into infinite loops, because it raises the question of why said object is indestructible. After all, if it was able to be damaged, then it would have turned to dust long ago. If I had to explain such phenomena, I might chalk it up to there being eddies and rifts in the flow of time, like a whirlpool. Sometimes things like this are just a part of how time moves. Another possibility is that some external force, be it destiny, fate, or some being that exists outside of our concept of time established this self-contained infinite loop for one reason or another. Maybe the being makes it in order to achieve a goal or cause an effect in reality. Maybe that watch you gave your dad saves his life, and you have something really important that you do in the future, so having you exist falls in with this entity's plans.
I'm willing to dismiss any paradoxes and/or infinite time loops if you actually call your time machine a timey-wimey ball.
The object part annoys me to no end, which is why I'm avoiding it the best that I can. (Two objects in the canon have a very complicated path through time, but I think I can tackle the extra twist without turning either one into an object without origin.) Information is a bit trickier. It might be possible for a phrase to pass between two people without degrading, assuming that their memories are good enough. I'm just trying to determine what is unimportant enough that it won't cause problems if it does degrade. I'm treating the process of discovery as important. I once read a time-travel story where they discovered a formula, cut out an unecesary bit, but later realized that it was needed. If their future selves had handed them the complete formula, they wouldn't have thought about that missing bit. (The story didn't involve actual time-travel. The formula was real but they ran it through a simulation where humanity used it to wipe themselves out.) I'm afraid that since it's fan-fiction, I have no control over the names. I'm not sure if it's canon or fanon, but the most powerful machine is called the Chronoplast, then there are Time-streaming Chambers, and then there are Portable Time-Steaming Devices. The PTSD appear to be one-use, but I'm instead saying that they are fragile and that the guy who was using them simply had a tendency to break them.
