|
In geometry, a hypercone (or spherical cone) is the figure in the 4-dimensional Euclidean space represented by the equation : It is a quadric surface, and is one of the possible 3-manifolds which are 4-dimensional equivalents of the conical surface in 3 dimensions. It is also named spherical cone because its intersections with hyperplanes perpendicular to the ''w''-axis are spheres. A four-dimensional right spherical hypercone can be thought of as a sphere which expands with time, starting its expansion from a single point source, such that the center of the expanding sphere remains fixed. An oblique spherical hypercone would be a sphere which expands with time, again starting its expansion from a point source, but such that the center of the expanding sphere moves with a uniform velocity. ==Parametric form== A right spherical hypercone can be described by the function : with vertex at the origin and expansion speed ''s''. An oblique spherical hypercone could then be described by the function : where is the 3-velocity of the center of the expanding sphere. An example of such a cone would be an expanding sound wave as seen from the point of view of a moving reference frame: e.g. the sound wave of a jet aircraft as seen from the jet's own reference frame. Note that the 3D-surfaces above enclose 4D-hypervolumes, which are the 4-cones proper. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Hypercone」の詳細全文を読む スポンサード リンク
|