A term coined by the Lights to describe the way the life time of organic species is laid out in the universe. From a four dimensional point of view the atoms which make up everything in the universe appear to be mostly static strings running from the beginning to the end
of the universe. When Jack first discovered this, he believed everyone was stuck reliving the exact same life over and over for eternity.
Things Can Change
At every point where a life form must make a major decision in their life the matter which makes up their bodies and the people closest to them diverge into two or more sets of matter, each following the outcome of a specific decision. Because no limit can be seen on the size of the universe, the Lights concluded that these divergences must be infinite in existence.
Walter pointed out to Jack that choosing a path leading to major change is difficult to do. He believed it was because a mind becomes accustomed to living life one way, but the reality is that most minds want change but not if it is forced on them. The difficulty comes from needing to pull the new path into the reality everyone else is experiencing. If a new path chosen by one mind affects other minds in a way they do not want, then they will attempt to prevent that mind from making the change. They do this by sending negative emotions to the mind, which eventually surface as doubt or fear in the mind making the choice.
The Lights came up with the idea of correcting species as a way to force them all from following a divergence which would ultimately lead to their self destruction. When there are only a small number of life forms in a species, corrections almost always work the first time since there will be few or no minds trying to prevent a move to a safer divergence.
With species like modern humans, there are potentially billions of minds who will resist any change. For this reason, Alpha One believes that corrections are no longer a viable option to helping them. He believes they would have better results by first determining which humans would accept them then contact those humans to enlist their aid in making the others chose a better path. Alpha Two believed that most sentient organic life forms had no ultimate purpose in the universe other than to be servants to the Lights.