Long has humanity looked to the stars and dreamt of worlds beyond. Naturally the soul of the explorer takes us along the road to discover the multiverse, and planes are the very worlds we yearn to explore.— Genos Dunkirk, The World
The planes constitute the multiverse, each with its own foundational laws. The current model for understanding the planes and how they interact is the Genos Dunkirk and books hosted in The Library.
Plane Types
While each plane is unique in form, the means of which it interacts with the rest of the cosmology is studied through classification into planar sub-types.
Planes that do not follow the patterns demonstrated by these subtypes are considered standard planes. Standard planes are typically self-stable spatial locations with three spatial dimensions a temporal axis. Certain unique exceptions of course exist, such as Tharassa and its two coexistent mirror planes (Falvada, and Eryndal). Despite the thorough understanding of their systems, information regarding the structure is delegated to books discussing those planes specifically, as the topic of this entry are the generalized structures found in greater cosmology.
Sub-Plane
Sub-Planes are planes that either rely on the structural stability of another self-sufficient plane, or have great spatial overlap with another larger plane. Sub-Planes have their own stable Aetheric Field, including operating leylines, and typically their own pantheon. Ashveil is one of the greatest known examples of a sub-plane, as a full plane that is anchored to Tharassa.
Demi-Plane
Demi-Planes are typically small planes that like a sub-plane, are not self sufficient, but instead of relying on another plane for structural stability, rely on the aetheric forces of an external source to lend spatial and aetheric stability. Demi-Planes do not have their own Aetheric Field or leylines with their only point of entry being that created by whatever force created it. Very rarely do demi-planes have their own Animist as well, with the creation of one being very difficult and only extended for demi-planes meant to be nearly permanent.
Destruction of demi-planes is rather frequent due to the inconsistent nature of their formation. If the source of aether that creates the plane is no longer able to support it, any items or energy stored within are typically released, phasing into whatever larger plane the demi-plane was created in. If the demi-plane is destroyed more forcefully, such as colliding magics the magical forces and content that constitute the demi-plane are aetherized and released with great force, often creating planar anomalies in their fallout.
Inner-Plane
A term originally describing planes that existed neatly within the [[#Planar Wheel Model]], now is used to describe planes that exist within the influence of a prime-plane. Inner-planes typically have easier access to various means of planar travel, as the prime-plane serves as a medium for which entities can interact. Most inner-planes follow similar foundational laws as their prime-plane leading to a consistency between them.
Outer-Plane
Outer-Planes is a concept created as part of the [[#Planar Wheel Model]] as a term to classify planes that existed outside the cosmological structure. While the term has little bearing following the current [[#Open Multiverse Model]], it is still used to describe planes that exist outside of the influence of a prime-plane.
Prime-Plane
Prime-Planes are massive planes that host within them many other planes. They serve as a medium for planar travel, and as bounds for foundational laws of their inner-planes. As of writing no instances have been discovered where a prime-plane exists within the bounds of another, but the Aetheric principles required for such a structure do work in theory.
Cosmological Models
A yearning to understand the multiverse has been with humanity since its inception, but science is a shifting medium and new understandings often replace older ones. Understanding of older working models is important for historical context, and for scholars to work to continue to evolve science toward a more complete understanding.
World Tree Model
The oldest model of our cosmological structure, its first written record was during the Divine Age. The World Tree Model operated on multiple metaphors for it's structure, with the most common being the depiction of an extra-planar structure referred to as the world tree. At the center of the tree was Tharassa and each other plane was a seperate branch of of this tree. Similar models existed that depicted Tharassa as a branch the same as the rest of the multiverse.
This model even at its inception was controversial as it did not account for things such as Asteanos, referred to at the time as the Astral Sea or the Astral Plane. Some of it's supporters more correctly supposed Asteanos as the plane itself.
Planar Wheel Model
The Planar Wheel Model has it's roots in the Divine Age, but due to the difficulty of planar travel during that age, it only took more prevalence during the Age of Dragons when planar travel amongst the [[#Tharassan-Planes]] became more common.
This model suggested that all of the planes existed on a disc or globe with Tharassa and it's mirror-planes at the center, and the elemental planes forming an inner ring, and the other inner-planes forming an outer ring. This was the working model for most scholarly study in history. As explorers pushed the boundaries for planar travel, eventually discovering outer-planes the terms for inner and outer-planes were used to make up for this discrepancy.
Tharassa-Centric Multiverse Model
As outer-planes were discovered, grew an alternative cosmological model called the Multiverse-Model. This model now referred to as Tharassa-Centric took precedence in the scientific model during the early Aetheric Age. The model penned the description of the prime-plane, although incorrectly attributing it as a unique quality of Tharassa. This model believed the multiverse to have an infinite number of planes, with Tharassa and the rest of the inner-planes holding a special purpose as the center of the multiverse to which all life radiates out.
Open Multiverse Model
The most recent and current model of the multiverse, the Open Multiverse Model disregards the concept that Tharassa is any way unique as due to the discovery of distant prime-planes. The understanding of prime-planes is that they are a coalescence of aetheric forces, forming a conglomeration of connected planes. The Open Multiverse model still is not the general consensus of the near-multiverse at the time of writing, and is written by Genos Dunkirk and adapted by the Library as it's working model for all research going forward.
Tharassan-Planes
With the Open Multiverse Model, Asteanos as the prime plane and each of the planes it contains as a classification of planes is referenced as "Tharrasan-Planes".
Planar Travel
Traveling between the planes has been a growing endeavor throughout history, as explorers, researchers, and adventurers yearn to explore ever outwards. There are a multitude of methods for traveling between planes with many notable ones being listed below.
Arcane
Many spells and magical forces are able to influence Asteanos to bend enough to connect physical locations between planes for brief moments, allowing teleportation and interplanar travel between Tharrasan-Planes.
Asteanos
Access to Asteanos exists in many forms, between, spells, stargates, and rifts. Asteanos is a relatively easy to access plane for most adventurers. Asteanos is littered with routes and means to access planes and often works as a bridge for adventurers seeking to travel to harder to reach planes.
Stable arcane doorways, Planar Gates are powerful magical artifacts that can form a connection between planes of any distance. Planar Gates are a staple feature of Asteanos and serve as the primary means of travel between it and other planes. Planar travel between outer-planes is unpredictable and difficult to replicate, powerful mages often will create planar gates to outer planes they discover as a permanent link to outer-planes.
Unstable arcane doorways, the consequence of powerful magic. Planar rifts are temporary spatial or temporal anomalies that rip the Aetheric Field to create connections to other planes. Exceptionally rare and dangerous, planar rifts are often used as one-way travel between planes.
Planar Bridges
Stable physical connections between planes, planar bridges are natural formations along leylines that make hidden connection between planes. Many planar bridges form between Tharassa and Ashveil in deep Tharrasan cave systems, and in upper Ashveil caves. Planar Bridges were the earliest form of interplanar travel and often lead explorers to make convoluted maps and theories to explain the impossible geometry they seem to create.
