Note: All discussion of universal physics is based solely on observations of 'known space'. As the universe is infinite, it is quite possible that these laws do not apply everywhere.
An Introduction to Spelljamming Physics
- As recorded by the venerable Tylinius Stryth,
Imperial Elven historian and sage
The entire prime material plane (the physical universe) may be divided into one of two areas: space that is within the crystal spheres (wildspace) and space that is outside the crystal spheres (phlogiston). Planets, stars, and celestial bodies are located within the spheres. The phlogiston (an incandescent 'rainbow ocean' of some unidentifiable and highly unstable substance), fills the space outside the spheres, coursing in turbulent streams between them. In effect, the spheres 'float' in the phlogiston.
The crystal spheres are opaque and unbreakable barriers which keep the phlogiston (often termed 'the Flow') out and wildspace in. Although they vary in size, even the smallest of the spheres is many trillions of miles in circumferance. Each of the spheres has a star system enclosed within it. A star system is made up of a number of planets, moons, suns, asteroids, and other celestial bodies, all locked in gravitational orbit with each other.
The interior of every known crystal sphere is filled with wildspace (vacuum). Consequently, the spheres are usually very dark inside, illuminated only by the stars that line the inner surface of the crystal shell and any fireworlds (suns) they may contain. In theory, a sphere could exist which possesses neither stars nor fireworlds, making it pitch black within, although there is no documentation of such a sphere in all of known space.
Outside the spheres, illumination is provided by the phlogiston itself, which gives off incandescent multi-colored light. Traveling through the Flow is akin to swimming underwater - one may see, but distances are often deceiving.
It is not possible to discuss spelljamming physics further without a basic study of gravity. Many planet-bound civilizations have deduced (incorrectly) that the amount of gravity is dependant upon the amount of mass an object has. The true nature of gravity, however, is that it is a constant. All objects over one ton in mass have gravity.
All objects that have gravity have the same amount of gravity, no matter the amount of mass involved. The gravity of objects the size of a moon or greater is central, so that it pulls down on anything on the surface of that object. On smaller objectsgravity arranges itself in a two-dimensional plane, which runs through the long axis of the object. This gravity plane is two-directional - were it running through a large wooden board, a person would be able to stand on either the top or the bottom of the board. (Of course, the person would feel as if he were standing on the 'top' of the board no matter which side he stood on.)
Gravity extends to the end of the object's atmosphere. If two objects with gravity pass within range of each other's gravity well, the object with the larger mass retains its gravity, while the smaller object becomes subject to the gravity plane of the larger.
Another misunderstood concept is atmosphere. Most world-bound societies maintain that, because wildspace is a vacuum, anything leaving the atmosphere of a planet would be excposed to vacuum. This would be true if not for the fact that every object carries with it an atmosphere equal to three times the ssize of that object. This means that if a person were to leave the atmosphere of a planet, he would carry breathable air with him (although not enough for him to get very far).
All of this, of course, would be interesting but irrelevant were it not for spelljamming technology, which makes it possible to cross interstellar distances in comparitively short amounts of time. Even the distance between a planet and one of its moons ranges in the hundreds of thousands of miles. Crossing that space using even the fastest conventional methods would take months. Using a spelljammer helm, the journey takes only hours.
A spelljamming helm translates mystical force (magic) into motive power. A ship powered by a spelljammer helm can move at a speed of roughly one million miles per day.
Due to both the vast number of spheres and worlds humans and demihumans inhabit and the enormous amount of time those races have been familiar with spelljamming technology, it is nearly impossible to determine at exactly what point mankind and the various other sentient terrestrial races first left their homeworld (homeworlds?) and reached for the stars.
What is certain is that when mankind finally did gain the starways, there were already other races there. Indeed, there is evidence of over thirteen separate spelljamming cultures which rose to prominence and fell to extinction before humanity ever arrived.
This is not to imply that humanity has yet taken its place among the stars as a full-fledged starfaring race. The vast majority of the human and demihuman races live out their entire lives completely ignorant of spelljamming technology and the starfaring community, or, at best, unmindful of it. To these 'gourndling' worlds speljamming is an irrelevance. There are wars to be won, crops to be farmed, and businesses to be run. Spelljammers and spacefarers are distant, intangible - much like knowledge of other planes of existance. It may be known that they exist, but it has very little to do with the problems of day to day life.
Spacefarers, also, have little truck with the groundling nations. There are, of course, places where trade flourishes between the two societies, but, on the whole, they exist largely independant of each other.
Not all races are so divided, however. Take for example the Arcane, the Giff, the Neogi, or the Dracon, all of which are completely spacefaring races with virtually no groundling populations.
However, even these societies are not as structured as most world-bound nations. The very size of the universe itself is what is makes organization so difficult. The crystal spheres are vast, and distances between spheres are even vaster. Would-be empires falter when trying to control, defend, and communicate across such distances. Conquering a planet is feasible, conquering a sphere possible, but most sages agree that conquering the entire universe would be impossible.
Of course, this has not stopped many races from trying to do so....