Dimension

A dimension is the infinite extent of a space with a certain number of spatial dimensions. There are 0, 1, 2, and 3-dimensional dimensions, and also 4-dimensional, 5-dimensional, and so on up to infinity. Dimensions are also called multiverses because each one contains an infinity of universes.

Dimensional Cosmology
Dimensional Cosmology is the study of the structure and composition of dimensions. Dimensions are actually distortions in the larger, flat space-time field of a reality. These distortions are caused by massive gravity fields of pure gravitons. These distortions warp the fabric of space-time into a specific number of spatial dimensions. There can be more than one dimension with the same number of spatial dimensions. For example, there can be multiple 3-dimensional dimensions. Universes form as bubbles spawned from quantum jitters within the dimensional space-time fabric. Quantum mechanical jitters are caused by the Heisenberg uncertaintiy principle, which only applies because of the distortion of space-time in a dimension. Outside dimensions, space-time is flat and perfectly unchanging, so the uncertainty principle does not apply. The gravitational tug of a dimension's gravity field is infinite, which makes escaping a dimension very difficult. Matter and energy originate within dimensions from the uncertainty principle, causing the energy of space-time to fluctuate due to quantum jitters, and clouds of virtual particles to appear. In addition to this, fluctuations and clouds of Nis drift into dimensions and stay there. In fact, Nis is believed to be the true engine driving all that goes on in a dimension. Without Nis, dimensions would become empty and full of dead universes. The laws of physics in dimensions may vary, and many dimensions contain magic. Magic can be generated in any dimension by tapping into the power of Nis. Dimensions can collide, creating pieces of "splintered" space-time. They can also very occasionally merge when conditions are right. It is worth noting that dimensions each have their own distinct time-stream, because time does not flow in the flat space-time of interdimensional space. Time only exists within dimensions, and flows differently for each one.

History
When realities were formed within existence, fields of gravitons, one of the first types of particles to exist, warped the perfect and flat space-time continuum of realities that contained space-time. These warps caused space-time to be distorted and imperfect, giving rise to the Heisenberg uncertainty principle within the warps in time and space (which were dimensions). The uncertainty principle created quantum effects and these effects gave rise to universes, matter, and energy. Nis also leaked into the dimensions from outside. The part it plays is not known, but is very fundamental and vital.