Cosmology

Cosmology is the study of the cosmos&mdash;the structure, organization and composition of all that there is. What most people would call the "known universe" is labeled the Prime Material Plane. It holds the world of Toril, the moon, the sun, and extends out into space to the stars. How far out into space is a question of cosmology, and the answer may depend on what cosmological model is used to describe the Prime Material plane. But there are many other planes of existence, some very much like the Prime and some so alien that they almost defy description. Like other dimensions, these other planes may overlap, surround, or penetrate the Prime Material plane, or they may be connected by some mystic avenue, often requiring magic to explore. Together, all the various planes are usually referred to as the "multiverse" and they are the the focus of cosmologists as they try to map, measure, and understand the planes and their relationship to life, to death, and to each other.

Cosmological Models
There have been numerous theories on the structure of the multiverse over the ages. The three major ones are as follows:
 * World Axis cosmology: The post-Spellplague model.
 * World Tree cosmology: The most commonly accepted pre-Spellplague Multiversal structure.
 * Great Wheel cosmology: A popular alternative to the World Tree theory.

Other Material Planes
Although it may seem strange it is a fact known to most cosmologists that the Prime Material Plane within which Toril resides is not the only plane of its kind in all the multiverse. Other worlds have been recorded to exist and each of the cosmological models has a way of explaining how they connect, relate, or coexist with one another. Of course the scholarly inhabitants of each of these Material planes thinks that theirs is the Prime Material plane, but cosmology shows that this is just a point of view. The three other Material planes discovered so far are:


 * Abeiran Material Plane
 * Although Abeir once existed in the same cosmology as Toril, the sundering split it into a cosmological twin of the local multiverse at the time, with its own separate parallel and fundamental planes. Other than the fact that it exists and that it occasionally interacts with the Prime, little is known of it.


 * Oerth Material Plane
 * A distant world visited by Khelben Arunsun the Younger, Oerth differs enormously from Toril, being a geocentric world around which its sun and planets rotate.


 * Terran Material Plane
 * A world called Earth is located here, of which little is known but which was once visited by Elminster in the Year of the Prince, wherein he met with a scholar there named Ed of the Greenwood.

Anomalous Planes
Though most planes are described by one or more of the cosmological models there are some exceptions that do not have a clear place in any known cosmology yet. These planes exist in unknown, nigh unreachable places and only a few well-informed scholars even know of their existence. These planes may drift distantly in one of the fundamental planes or lie entirely outside of the World Axis or any of the other models. These planes often do not follow the same physical laws as do the other planes and are immensely inhospitable.

The known anomalous planes are as follows, though undoubtedly more exist:
 * Far Realm
 * The Far Realm is a distant and terrifying plane that lies "outside" of the rest of creation. This maddening realm is feared for its power to twist unfortunate visitors into gruesome monsters and it is from here that aberrations come.