Fiction:Spatial anomaly

A spatial anomaly or spacetime anomaly is a region of spacetime where the geometry of space becomes obviously non-Euclidean, and gravitational effects cannot be treated as a force between, or acceleration produced by, massive objects. The term is not a technical one and as such lacks a rigorous definition, but many starfleets' scientific departments define a spatial anomaly as being a region where gravitational effects exist that cannot be described using the formalism of gravitoelectromagnetism either qualitatively, or quantitatively with some higher-order corrections. Colloquially, gravitational lensing and gravitational waves may even be referred to as "anomalies", although these are in fact ubiquitous phenomena.

While spatial anomalies typically involve temporal disturbances, they are not to be confused with temporal anomalies, timeline discontinuities and intersections, although temporal anomalies are often classified as a category of spatial anomaly.

Black holes
Even in the simplest nonrelativistic description of gravitation, Newtonian gravity, "dark stars" exist where the gravitational pull is so great that even light cannot escape. A key part of this is the concept that a certain amount of kinetic energy is required for an object to escape a celestial body's gravity, and if this energy were put into the object at once, it would have a particular speed known as the "escape velocity". For a dark star, this escape velocity is greather than or equal to the speed of light. However, it would still be possible to leave the dark star by continuous acceleration, in the same way that spacecraft can leave planetary orbit without reaching the planet's escape velocity.

The same is not true for their real-world equivalents, black holes. For these, the dark star's escape velocity corresponds to the existence of an event horizon, in which the arrow of time itself is bent so much that time and space effectively swap places, such that travel into the future is identical to movement towards the centre of mass. Escape really does require the ability to travel faster than light, or more generally backwards in time. This feature marks the black hole, an otherwise simple (albeit extreme) gravitating object, as a naturally-occuring spatial anomaly.

Topology changes


A more drastic departure from gravitoelectromagnetism is where not only the geometry but also the topology of spacetime is altered, connecting otherwise seperate parts of spacetime together. This is a very large group of phenomena, and many different schemes of subdividing it exist.

By far the most relevant topology changes to a spacefaring society are those that allow for faster-than-light and interuniversal travel, particularly wormholes (phenomena that are purely restricted to hyperspatial are, in general, not counted amongst the spatial anomalies). Although far less common, wormholes and similar structures also allow for travel backwards and forwards in time, to pocket universes, and to other. Uncontrolled topology of this type can be highly risky, both as a result of leading to dangerous locations and due to the possibility of destructive collapse.

Some topological defects in scalar fields also impact the topology of space via gravity, particularly cosmic strings which have a total angle less than 360 degress around them. These are no more harmful than any other celestial object unless collided with, although they can emit gravitational radiation and decay (especially if they form loops).

Dark matter
One of the key features of gravitation is that every change in geometry can be traced back to a source, and depends purely on the source's energy, momentum, and stress (in gravitoelectromagnetism, the effect of stress is negligible, while Newtonian gravity also ignores the effect of momentum). This leads to a set of spatial anomalies which involve gravitational effects (potentially including other anomalies such as topology changes) that seem to lack an appropriate source. The undetected source is known as "dark matter", and while many varieties exist, most of it is caused by hypermatter, while some localised occurancies are the result of.