|“||Mr Frog told me once that the universe is like a floating soap bubble, and that Parasol, Ballpoint and Eris are like tiny bubbles stuck to the outside of it. ... smaller soap bubbles can be inside the main one, floating there by themselves, moving about with little effort..."||”|
Bubble Dimensions (also known as "Bubble Universes", "sub-dimensions" and "sub-universes") are artificial dimensions that act as miniature, self-contained universes. These universes can be quite small, such as the size of a room, to quite large, encompassing a planet or more. As they do not actually exist within their Parent Universe, they can move about with almost no effort at all. Switching parent universes is somewhat more difficult, and very resource-consuming. Thus, bubble dimensions are often used as permanent outposts, such as the ones Ballpoint creates.
A bubble dimension does not have a fixed size relative to the universe it is contained within. For example, one could contain a bubble dimension the size of a city within the space an apple occupies in the parent universe. This can lead to rooms looking "bigger on the inside".
There are three different types of bubble dimensions, each with different statistics between size, energy expenditure, maneuverability and so forth. A single dimension can, with the appropriate equipment, switch types. This cannot happen naturally and is entirely artificial.
Anchored bubbles are anchored to either a parent universe, orbital bubble, or solitary bubble, by one or more "access points". Creatures and objects may enter and exit the dimension through one of these points. In addition to being capable of being anchored to parent universes, it is also possible to anchor them to a floating or solitary bubble. Anchored bubbles do not take up any physical space in the parent dimension, and one can actually walk in a circle around the access point without ever entering the anchored bubble.
Anchored bubbles are the simplest and easiest to maintain, requiring the least energy. They are also often the smallest of the three types, sometimes only containing a space the size of a single room, or a set of rooms.
With the appropriate equipment, an anchored bubble can temporarily shut off its access points, essentially turning it into an orbital bubble. They are, however, permanently attached to their parent dimension.
A well-known anchored bubble is Mr Frog's Laboratory.
Orbital bubbles "orbit" either a parent universe or a solitary bubble, although they do not actually contact them at any point. The only possible methods of traveling from a orbital bubble to its parent dimension is either via portal, or by exiting the orbital bubble through one of the bubble's edges, which will place the object or creature in a seemingly random point in the parent dimension. The exact mathematics behind this have not yet been worked out.
Orbital bubbles are the second simplest type of dimension to create and maintain. They require a decent amount of energy, however, to keep them attached to their parent dimension - more than either anchored bubbles or solitary bubbles. Fortunately, it is nearly as simple and cost-efficient to create a large dimension of this type as it is a small one, and for this reason it is logical to opt for as large a dimension as possible when creating one.
If it is deemed necessary, it is possible to remove an orbital bubble from its parent dimension entirely, converting it to a solitary, or roaming, bubble. This process requires an incredible amount of energy, and is not often attempted.
Solitary bubbles are not attached to any other type of universe or dimension, and are completely self-maintained. It is theorized that an essentially infinite quantity of solitary dimensions exist outside the normal realm of space and time - any one of these can be accessed with a megaportal, provided you know the appropriate coordinate code. Because of this, there is essentially no cost in keeping a solitary bubble in existence.
It is extremely difficult to get portals to function in between solitary bubbles and other non-connected dimensions, and doing so requires a very large amount of energy. For this reason they are often put into "orbit" around a parent universe, and converted into orbital bubbles. This process is analogous to putting a vehicle in orbit around a large mass such as a star, and can actually provide additional energy if executed properly.
A well-known solitary bubble is Eris.