Universes by shape and size

This classification organizes universes by their shape and size. Universes can have different shapes based on the curvature of their dimensions as well as their own topology.

## Information

Some shapes allow for an infinite sized universe while others force it to be necessarily finite, unless the properties of such a universe breaks the laws of geometry as we know them. A dimension can be so extremely curved that it just folds over itself or multiple dimensions can be folded into each other. Curvatures also need not be constant through the entire dimension which opens up a new infinity of more complex options. It can also become a little trickier when dealing with universes with different types of infinite sizes though.

All this results in extremely many different possible shapes for the actual universe, and to that one must still add its own topology.

## By Shape

Each dimension of the universe can have a different curvature and the dimensions can relate to each other in different ways, being perpendicular, angled in other ways or even parallel. What angles do they make in relation to each other. It could be any angle at all. Usually they are seen as forming 90º angles between each other but that is not always necessarily the case and the difference can be meaningful in some types of geometries while under other types they can form angles that would otherwise be considered impossible.

If their curvature allows it or their topology calls for it, each dimension can either be open or closed forming some kind of loop structure where it links back to its origin or to some other point along its length. These loops can be simple, equivalent to circles, or much more complex, more akin to knots of some kind. Open dimensions never return to a previous point and go on until they end or forever if they are infinite.

Examples:

* A Flat Universe is a universe that, as the name implies, its space has no curvature, being entirely flat.
* Open universe - A universe with constant negative curvature, and is in the shape of a hyperbolic space.
* Closed universe - A universe with constant positive curvature, and is in the shape of a hypersphere.
* Irregular universe is a universe which has space without a constant curvature. It can have positive curvature in some parts and negative in others and even be flat in other parts. The degrees of curvature, positive or negative, can also vary from place to place. The more it varies and the sharper the variations the more irregular the universe is. A low irregularity universe would be one with some curvature that decreases slowly over distance tending to some limit but never actually reaching it.
* Uncertainly shaped universe is a universe where the curvature of space is subject to the uncertainty principle and the observer effect. It is not possible to both measure precisely the curvature of space and some other property at the same time.
* Observer based irregular universe is a universe with a curvature that changes over distance based on the observer position. At the observer position it has a certain constant curvature but at distance that curvature either decreases or increases regularly as a factor of distance of the observed point. If the curvature approaches 0 with distance it is possible that it just flats out at the distance or it can continue to change and start to curve in the other direction. If it gets more and more curved with distance it can just tend to a certain limit that it never reaches or it can continue to curve without a limit up to infinite curvature at infinite distance.
* Universe with a constant positive curvature but is still infinite in size. This would normally be impossible but can happen in one of two ways: either the universe has an impossible shape or it follows different laws of geometry which allows for such situation. Such universes that follow different laws of geometry can also allow for other equally impossible topologies.
* Universe with a variable shape and/or topology. It changes constantly either regularly following some kind of pattern or formula or in a more random way. The change can be cyclical or never repeat. It can be a one time event with the shape stabilizing after some period or it can continue changing permanently. It is possible that its spacetime fabric is malleable and/or unstable, existing somewhat like a fluid or gas, never finding a fully static position. Maybe the changes are not an inherent property but are a consequence of external forces applying pressure on it.
* Universe that has a global frame of reference which means that it is possible to identify individual locations inside it in an objective way instead of needing to refer to them in relation to something else. Some of these universes can have a well defined center position, possibly sometimes occupied by a specific star or planet, probably fixed in that position. For that to remain constant, whatever exists on that position would be static in space. Also, if space in such an universe is expanding, the space in that point is not and remains static. Space would expand only in relation to that point and based on how distant it is from that point. The more distant the more it would expand.
* Universe which is just a projection of an higher dimension universe into a space with the same number of dimensions it appears to have. So a universe with 3 spacial dimensions could actually be a 4 spacial dimensions universe being projected into a 3d space.
* A universe with any finite size and well defined positions due to a quantized space, such that each particle can only be on one of those positions but not in between them. Due to its finite size such universe will also have a finite amount of such positions. Such universes has been named subverse on this wiki.
* A partial subverse is a universe with some discrete dimensions (like a subverse) and other continuous ones (that work more like the normal notion of a mathematical space).

## By Size

Each dimension of the universe can have its own size, from a limited well defined size to any type of infinite size.

Examples:

* A Protoverse is a universe so small that it only has the space for a single unique position, corresponding to a single point. It is considered to be of infinitely small size, actually having 0 dimensions.
* A Nullverse is an even smaller universe without any size at all. There are no positions or locations inside it, not even a single point. It is considered as having -1 dimensions.
* An infinite subverse is just like a subverse in that it is made of quantized discrete space but contains an infinite number of such positions inside it.
* A universe which is much smaller than normal is called a Microverse. These structures usually exist at a lower cosmological level than the normal one when possible, like a micro-multiverse existing at the level of a universe.
* A universe with a relatively "small" finite size is usually called a Pocket universe. Usually this classification would be reserved for universes containing not much more than a single star and some small planet orbiting it but sometimes the name is also used for universes as large as the size of an entire galaxy. When it is small enough that not even a single planet fits inside it, and it still contains a recognizable place, possibly habitable, it is usually named as a pocket plane instead for at that point it is clearly not following any recognizable laws of physics and its nature is very different. They can be seen as special cases of Microverses that are self-contained.
* A universe which is much larger than normal is called a Macroverse. These structures usually exist at a higher cosmological level than the normal one, like at the level of a multiverse all up to the level of an omniverse.