A Dimensional Vortex is the stretching of reality that enables dimensional travel. Through the Dimensional Vortex, it is possible to get to any of the existing dimensions. The Dimensional Vortex can also be used as a form of travel in the same dimension, by hopping into another dimension and then hopping back into the one that was originated from.
Dimensional Vortexes are typically created by an anomaly that doesn't happen naturally (like a Dimensional Window) -- a human with proper technology can create a Dimensional Vortex. A Dimensional Vortex can also be referenced to as a wormhole, however Dimensional Vortex is a more appropriate word as it interacts with dimensions.
A Dimensional Vortex doesn't occupy a space as you are right now. A Dimensional Vortex can only be described as in between dimensions, while not actually being a dimension itself. It is possible that the Dimensional Vortex's energy is either the lowest or highest form of energy among possible dimensional energies, and may even be siphoned from the AEONE.