See: World Line, World Line Shift, Attractor Field instead[]
World Line Convergence refers to a phenomenon that causes multiple world lines within the same attractor field to converge to the same result.
The term convergence refers to events which are fated to occur on a world line regardless of action taken, while divergence (not to confuse with divergence value) refers to the attempt of changing predetermined events. Typically, events of mass confusion enable a divergence great enough to change attractor fields; a notable example in the series is the panic revolving the Y2K bug.
Description[]
As long as a world line is within a certain attractor field, it will always converge to the same result as other world lines within the same attractor field. This phenomenon is referred to as World Line Convergence, where a group of world lines all converge on a single event. The exact circumstances of the event in question do not matter, but as long as the event takes place, the world line will converge. Additionally, due to Convergence, it is impossible to prevent the event from occurring unless history is altered enough to prompt an Attractor Field change.
For example, Mayuri Shiina's death occurs in all of the world lines in the Alpha Attractor Field due to all of them converging on the same "result". It does not matter whether Mayuri is murdered, dies in an accident, or perishes of natural causes, but the world lines will continue to converge on her death unless the world line changes to a world line within an attractor field where Mayuri does not die in 2010, such as the Beta Attractor Field.
It is impossible to escape World Line Convergence without entering another attractor field by changing history, which can only be accomplished through time travel.
The Steins Gate World Line is a world line that lies between the Alpha and Beta Attractor Fields, and is unaffected by either. As a result, the future of this world line is unknown, but different from the futures of world lines in the Alpha and Beta Attractor Fields.
In relation to the series, the term causality is used to describe when human action is insignificant in achieving divergence, meaning that human action only slows the occurrence at best.