While one might fear the arising of temporal paradoxes and accompanying existential threats, basic features of the design assure existential stability. In particular, old objects are never overwritten by new ones, but new ones are rather created to exist alongside the old ones.
The commonly expressed fears concerning the rewriting of history are based on simple misunderstandings, such as thinking that the old is truly replaced by the new, rather than existing alongside it. While the main references are usually updated to point to the new rather than to the old, the objects of which the new is composed are distinct from those of which the old is composed, and the old objects remain at least until after the last active references to them are dropped.
Thus, an older timeline may be superseded by a newer one, but the old contents remain distinct from the new ones. They exist in parallel, possibly branching out from a common point. Old contents are dropped only if no longer referenced to. Thus, anyone and anything playing any kind of active role in existence, even that of being pointed to as a long-superseded branch of reality, is assured of existential continuity.
Branching and merging
A branch of reality is a line of events. Several lines may extend from each event, so that reality branches out over time. Typically, one or several main branches exist, alongside temporary branches which appear and are then superseded by events placed in one or several of the main branches.
Some developers prefer to add events linearly to a branch one by one, whereas other developers line up their events in side branches before integrating them into the main branches. Two main styles of such integration exist:
- Picking events from various branches and arranging them into a linear sequence in a target history. The order of events may possibly be rearranged in the process. Some events may further be dropped and others duplicated, as needed.
- Creating merge events which join several lines of history at a single point, from which a common line then proceeds. This may sometimes cause a confusing duplication of events in memory, when several merged histories contain the same or similar events. At the point of merging, the developer modifies the state of things so as to resolve the inconsistencies between the different histories. The events of the different histories brought together will all seem to have occurred after the merge, making for a larger and superficially conflicting historical record.