The "Nexus" is the El-Aurian name for a nonlinear temporal phenomenon capable of delivering an individual to a non-corporeal Utopian existence. The entrance into the Nexus was a temporal flux energy ribbon which crossed the Milky Way Galaxy every 39.1 years.

The first known contact with the Nexus was in 2293 when two ships transporting El-Aurian refugees were caught up by it. The just-christened USS Enterprise-B responded to the ships' distress calls. Captain James T. Kirk, who was a guest aboard the Enterprise and had been implementing modifications to allow its escape, was lost into the Nexus when it struck and severely damaged the ship. Soran planned to destroy two stars (Amargosa and Veridian) the resultant gravitational waves of which would alter the course of the Nexus, forcing it to pass through the planet Veridian III, where he would enter it. Captain Jean-Luc Picard discovered the nature of Soran's plan and set out to stop him, though he failed and was swept up into the Nexus himself. (Star Trek Generations).

Parallel universes really do exist, according to a mathematical discovery in 2007 by Oxford scientists led by Dr David Deutsch.

The parallel universe theory, first proposed in 1950 by the US physicist Hugh Everett, helps explain mysteries of quantum mechanics that have baffled scientists for decades, it is claimed. In Everett's "many worlds" universe, every time a new physical possibility is explored, the universe splits. Given a number of possible alternative outcomes, each one is played out - in its own universe.

According to quantum mechanics, nothing at the subatomic scale can really be said to exist until it is observed. Until then, particles occupy nebulous "superposition" states, in which they can have simultaneous "up" and "down" spins, or appear to be in different places at the same time. Observation appears to "nail down" a particular state of reality, in the same way as a spinning coin can only be said to be in a "heads" or "tails" state once it is caught.

According to quantum mechanics, unobserved particles are described by "wave functions" representing a set of multiple "probable" states. When an observer makes a measurement, the particle then settles down into one of these multiple options. The Oxford team showed mathematically that the bush-like branching structure created by the universe splitting into parallel versions of itself can explain the probabilistic nature of quantum outcomes.