In mathematics, an '''eigenplane''' is a two-dimensional invariant subspace in a given vector space. By analogy with the term ''eigenvector'' for a vector which, when operated on by a linear transformationlinear operator is another vector which is a scalar multiple of itself, the term '''''eigenplane''''' can be used to describe a two-dimensional plane (mathematics)plane (a ''2-plane''), such that the operation of a linear transformationlinear operator on a vector in the 2-plane always yields another vector in the same 2-plane.
A particular case that has been studied is that in which the linear operator is an isometry ''M'' of the hypersphere (written ''S3'') represented within four-dimensional Euclidean space:
:
where '''s''' and '''t''' are four-dimensional column vectors and Λθ is a two-dimensional '''eigenrotation''' within the '''eigenplane'''.
In the usual eigenvector problem, there is freedom to multiply an eigenvector by an arbitrary scalar; in this case there is freedom to multiply by an arbitrary non-zero rotation.
This case is potentially physically interesting in the case that the shape of the universe is a multiply connected3-manifold, since finding the angles of the eigenrotations of a candidate isometry for shape of the universetopological lensing is a way to scientific methodfalsify such hypotheses.
[The article Eigenplane is based on the the dictionary Wikipedia, the free encyklopedia. There you will find a list of all editors and the possibility to edit the original text of the article Eigenplane.
The texts from Wikipedia and this site follow the GNU Free Documentation License.]