Terminology

Observer Event Stream (EOS)
In 2590 it has been proven that time is only a relative progression of events for an observer such as a human. This progression of events for the observer was then called "Observer Event Stream" or EOS. For the sake of keeping the language consistent, time isn't different from how you know it; EOS is just used for the span of time observed by an observer. If the observer travels to different points in space and time, his EOS will remain consistent as he jumps.

For example, if Earth is characterized as an observer, Earth's EOS will remain consistent while the time outside of the field can change (meaning that anything within the field continues on a regular progression of EOS, while time outside of the field can jump around).

Now, if the Earth is in multiple time frames at the same time and yet does not exist in regular space, it is possible that the field has desynchronized Earth from it's regular EOS, creating new timelines for every point in time where the Earths exist simultaneously, which will cause a collision between the new universes created. In 2601 it has been proven that if two universes collide, the two universes will merge at particular points creating a fixed point in time and space where something will happen no matter which version of the universe you're on.

~ LAINSY (slightly edited for spacing and making sense without the context of the RECALL device)

(From http://forums.unfiction.com/forums/viewtopic.php?p=901181#901181)