Editing Singularity theory (section)

==How singularities may arise==
In singularity theory the general phenomenon of points and sets of singularities is studied, as part of the concept that manifolds (spaces without singularities) may acquire special, singular points by a number of routes. [[3D projection|Projection]] is one way, very obvious in visual terms when three-dimensional objects are projected into two dimensions (for example in one of our [[human eye|eye]]s); in looking at classical statuary the folds of drapery are amongst the most obvious features. Singularities of this kind include [[caustic (mathematics)|caustic]]s, very familiar as the light patterns at the bottom of a swimming pool.

Other ways in which singularities occur is by [[Degeneracy (mathematics)|degeneration]] of manifold structure. The presence of [[symmetry]] can be good cause to consider [[orbifold]]s, which are manifolds that have acquired "corners" in a process of folding up, resembling the creasing of a table napkin.