D&D: Nature of the Planes

I've often wondered about how a plane can be infinite and size and yet bounded such that it is coterminus with another plane. I prefer to think of a plane as just that - a surface. Wrap that surface on a sphere and voila, seemingly infinite in size but having defined beginning and end. Move one way long enough and you arrive back where you were. The same could be said for the inside of a sphere.

I've pondered how I would like to see a planar structure in B/X D&D and I believe I finally have a solution - BUBBLES!

Imagine a large bubble of some thickness - this is the Prime Material Plane. The bubble is so large that it seems infinite. The interior of this bubble is filled with Ether which separates the Prime plane from the other Inner Planes. The Ether also permeates the Prime Plane and all the Inner Planes. At the core of the Ether is a large bubble split into six chambers - like bubbles blown into a single bubble. The upper bubble is Positive Energy, the lower bubble is Negative Energy, and the middle ring comprises the Elemental Planes of Air, Water, Earth, and Fire. The Positive and Negative Energy planes have vortexes that erupt out from their central surfaces, piercing the Ether and Prime Material Planes and continuing beyond. Like a giant electromagnet, the Positive Energy plane spews forth energy into the multiverse and the Negative Energy plane sucks in the energy (again, think of the magnetic lines of force around a planet with the Energy planes functioning as poles of the magnet) They function as the Planar Axis (Axis Mundi?) and all rotates slowly around this axis.

Outside the Prime Plane Bubble is a vast expanse of nothingness filled with stars and a staggeringly large variety of planets and asteroids. This is the Astral Plane. Nothing can exist physically within the Astral Plane - there is no air to breathe, no gravity, no pressure, and nothing to draw sustenance from. From the Astral Plane, the Inner Planes can be seen through the Prime Material Membrane as a swirling galaxy of various colors with a brilliantly glowing top and dark, shadowy bottom.

The Astral Plane contains bits of matter left over from the creation of the Prime Material, or portions of the Prime Material Plane that have been lost to the void of the Astral Plane over the millennia. These form planets (more spherical "planes") of various sizes and qualities. Those that are vibrant spheres filled with positive energy and conducive to life are considered to be Planes of Law; those that are filled with negative energy or cannot support life are considered to be Planes of Chaos. Others might be Neutral Planes with a mix of both energies.

Planes in AD&D are said to be made up of layers. These layers could be planets in a single star system. So the Seven Heavens could be represented by seven planets, each with its own unique environments and perhaps all joined together by a network of gates. The Abyss in AD&D is said to be made up of 666 layers. This could be presented by an asteroid field, the remains of a planet of demons which they destroyed in a great war but still inhabited by them. The River Styx could be a wormhole vortex joining all the negative energy Outer Planes, and only Charon knows how to navigate it safely - all others who fall into the vortex are lost and may end up sucked back to the Negative Energy Plane.

Travel through the Astral Plane is done as a disembodied spirit or soul. Mental energy thus determines the speed of travel here. Most travelers only move through the Astral Plane to get to another destination on the Outer Planes. Some few decide to remain in the Astral Plane and explore the place. The Gith reside in the Astral as disembodied psychic images, and may decide to attack those who invade their realms. Many outer planar creatures can move through the Astral Plane as well, and may be encountered here in non-corporeal forms. A new body is created by the soul or spirit when they arrive on an outer plane out of the native materials. This body resembles the one the soul or spirit had on the Prime Material Plane, but may have some strange alterations based on the plane they travel to (like glowing eyes, mineralized flesh, or what have you). When the body is destroyed, the soul/spirit is sent back to its home plane where it may die from the shock (saving throw or Constitution check, not sure which should apply). A silver cord connects a traveler to its home plane so long as it is still alive. A dead traveler without a cord is lost unless it worshipped some Immortal in an outer plane. Such a traveler is then reeled in to the outer plane where that Immortal dwells. Thus, a living being has not only a silver cord but also a connection to whatever faith they follow in the Afterlife. Such souls/spirits are used by the Outer Planar Immortals in some way to empower them.

The Astral Plane is nearly infinite in size, but may be just another bubble. The Astral space is the void within the bubble between its furthest boundary and the Prime Material Plane, sparsely filled with Outer Planes. Each "multiverse" could thus be a system of these nested bubbles. Related planes are all connected by a network of gates. A Manual of the Planes could list all the gates, how they are activated, and where they lead - a most potent artifact if found! The Ether Cyclone and Psychic Wind defined in the AD&D rules could be places where the Ethereal plane touches the Astral Void via vortexes through the Prime Material Plane. Within the Prime these are invisible and have no effect, but they are openings through the bubble membrane that resemble violent tornadoes in reverse within the Ether and violent blowing nebulae in the Astral - in essence these are locations where Inner Plane materials are being fed into the Astral Void to help populate it with matter and energy. Obviously, these vortexes meander over the surface of the Prime Plane Bubble and their position might be detectable to those with the proper spells. Such an alignment of a vortex through a homeworld on the Prime could portend dire times for that world, but can only be seen by those with the proper sight (some magical detection, ability to see into the ethereal or astral planes, etc.).

When Outer Planar creatures are slain on the Prime Material Plane, they are returned to their home plane, more or less intact (but they may lose the ability to travel astrally for a while, thus trapping them on their home plane). Inner Planar creatures are essentially disembodied spirits that have no Outer Planar connections. They are immortal for all intents and purposes. They cannot freely enter the Prime Material Plane without a gate or magical summons. When they are destroyed on the Prime Material, they reform in their native Inner Plane. This explains why magic-users need such large volumes of pure elements to summon forth an elemental creature - they need it to form their bodies!

I'm sure there are some nuances that I'm forgetting, but that structure should be enough to provide challenges for planar adventures for some time to come. I need to determine the nature of Immortals and better define which creatures should be considered immortal. I see demons as evil spirits existing in the Outer Planes - they have no material forms of their own but instead form bodies from their environment when necessary. This explains their varied appearances since they can alter what form they take based on their power.

What exists beyond the Astral Plane? Perhaps a Dimension of Madness where the Old Ones dwell, constantly trying to invade the multiverse and infest it with their powers. Or perhaps demons are natives of that place and have begun an invasion into this reality. Every campaign has an ultimate evil that all the mortals and immortals should fear and be wary of....