The fourth dimension is time, as defined by Einstein in regards to the Theories of Relativity. The Spatial dimensions are those of height, length, and depth. The fourth dimension can be related to a
hypercube, much as the first dimension is related to a line, the second two lines connected at perpendicual angles to one another, and the
third dimension being a cube. The fourth dimension is(sometimes) associated with the
space-time continuum.
It is truly
inane to travel to a
universe that is based only upon the fourth dimension, as that woould include
only time, and no being could truly exist.