One should always study the science before constructing a time machine. Feynman diagrams illustrate the effects of smashing atomic particles with a particle accelerator. Abe and Aaron do not say the box does this, but that it has similar properties. When you break apart atomic particles, they disperse and interact with one another, becoming more reactive particles as they decay. There are three main components. They are at times, attracted toward one another and at times, repelled from one another. The possible reactions seem infinite, yet causality is always preserved. Renormalization eliminates the amplitude of self-interactions.
In Primer’s time travel, the possibilities are also infinite but the results are likewise finite, even predictable. As events are repeated, the branches of the timelines connect with each other. Abe and Aaron appear as three main causes of the past, present, and future. At times, Abe and Aaron are drawn together, as well as drawn apart. At times, they interact with their other selves and at times, they avoid one another. They can act alone in secrecy or they can work together.
So, there is an infinite number of possible interactions between our two players and their components of past, present, and future. Yet, there are a limited numbers of actions that will occur. In any timeline, one component may choose to fail-safe. When though, we arrive at the party, there is only one result that will not cause one component to send the timeline into a repeat of the past events. Sooner or much later, the branches recombine into the end result. As to the surviving components; some will exit or continue into the future while others may become absorbed into the past repetitions (the feedback loop). Their actions repeat themselves over and over without escape. This is just like the particles in the accelerator which both form and decay simultaneously.
