In the physical universe, the concept of time is always positive. However, if there are simultaneous parallel time dimensions within the physical universes. Every physical universe is associated with one time dimension and innumerable parallel time dimensions. The concept of time is always starts at zero – the time of the big bang in the physical universe. But according to researchers in contemporary physics, a parallel universe can concievably have no time dimension or time can become negative in that environment. The lack of time as a dimension or presence of negative time (or anti-time) makes living through that environment very different form the physical universe. Space becomes finite and time becomes non-existent or retraceable factor. As we can walk around in the physical universe from point A to point B, in the parallel universe, it can be possible to walk from one time to the next time, or back in time.

In Star Trek, an anti-time eruption is a multiphasic temporal convergence in the space-time continuum, a spatial anomaly resulting from the breakdown of the subspace barrier between time and anti-time. In an alternate timeline, a rupture was formed as the result of the convergence of three identical inverse tachyon pulses from three time periods - 2364, 2370 and an unknown future date - at a single point in space. The rupture, located in the Devron system inside the Romulan Neutral Zone, expanded as it traveled back through time due to the unique nature of anti-time. Eventually, the anomaly would have expanded to cover the entire Beta Quadrant in the distant past.

A highly-focused energy source, the anomaly's energy output was found to be equivalent to ten G-type stars. The energy emitted was in the form of temporal energy, which caused Geordi La Forge's DNA to regenerate, giving him normal sight. Several other crew members reported old scars healing, and nurse Alyssa Ogawa's fetus was killed by the reversion. The anomaly's presence at Earth in the distant past would have prevented the formation of the first proteins, and ultimately, all life on the planet. Eventually, the cause of the rupture was uncovered, and a concerted effort from the Enterprises of each time frame was successful in reforming the subspace barrier via a static warp shell, erasing the anomaly and the timelines it created. (TNG: "All Good Things...")