
This section will be added to and tweaked, simply because the mun sucks at first drafts.
At any point in time, only one Janie exists. As a time traveler, she will never meet any other versions of herself, because they are all the same person.
She can travel to any point and time, as long as she knows when and where. If she travels without that knowledge, she'll end up in a random location. I use Quantum Entanglement to an extent for her time travel. (The mun is only using that as part of her theory as she learns more about quantum physics)
The simple way I explain it, is that Janie can instantly 'bounce' from one time to the next. The natural or 'wild' travel is seemingly random. An organization of fifteen other time travelers was able to figure out how it linked to physics, and if they do the proper calculations and use a specialized machine, they are able to control where and when they travel.
Janie is not an expert at this machine yet.
The machine looks a lot like a cross between and i-phone and a graphing calculator. It works by entering an equation that corresponds to a time and location, and transporting anything attached to the machine to said time and location. It also has a camera, data port and contains the future equivalent of an electronic encyclopedia. Janie's device also contains games, a music player and a cell phone of sorts.
If the device is lost, Janie's travel will be uncontrolled and she will constantly bounce from time to time.
Destiny cannot be changed by any of the travelers. If attempted, the destined events will happen anyway.