For the third day of this tour, I'd like to talk about the phenomenon that the story is based on: parallel universes. The parallel universes in the Bright Empires series are mostly the same, but are lined up differently in reference ti time. For instance, if you travel on a ley, you may end up in 1820, or even in 33 A.D.
There are some similar theories and speculations (novels) about parallel universes. Stephen Hawking's Multiverse Theory is one of these. Here is a concise definition:
"The multiverse is a theoretical framework in modern cosmology (and high energy physics) which presents the idea that there exist a vast array of potential universes which are actually manifest in some way." -About.com
To make it a little more clear, the Multiverse Theory states that every potential event creates another universe in which that even takes place. For instance, if I high-five my brother tomorrow, and make cupcakes later on, those events will cause universes to exist in which 1) I don't high five my brother but still make cupcakes 2) high five my brother but don't make cupcakes and 3) high five my brother and make brownies. You can see that there are infinite possibilities. Thus, there are infinite universes. This blows my mind, personally. I don't want to think about it any more.
A simpler, less mind-blowing version of this theory is presented in the movie Source Code. If you haven't seen it, this next section contain spoilers, so you are duly warned. The protagonist in the movie is a man stuck inside a machine that allows him to live the last eight minutes of a man's life over and over again. He lives out the last eight minutes of a man who was the victim of a train bombing, trying to figure out who the bomber was. During these eight-minute periods, he does different things each time, each involving a woman he is sitting beside, who is another victim. He becomes desperate to save her, but never succeeds. In the end, you find that each time he did something different, he created a slightly different universe with a new outcome.
Bryan Davis writes about a similar effect. In his Echoes From the Edge series, there are multiple universes (only three, in this case), but they are the same, until people travel between them, changing them up a bit. However, this does not create more universes like the examples noted previously.
The multi-verse theory and the similar ideas have been really influential in today's media and literature. It is the source for much speculation, literally with infinite possibilities. In The Bone House, no universes are created by potential events, as far as has been revealed. Some have been changed in respect to others, but not created by potentiality.