| Tesseract 8-cell (4-cube) | |
|---|---|
| Type | Convex regular 4-polytope |
| Schläfli symbol | {4,3,3} t0,3{4,3,2} or {4,3}×{ } t0,2{4,2,4} or {4}×{4} t0,2,3{4,2,2} or {4}×{ }×{ } t0,1,2,3{2,2,2} or { }×{ }×{ }×{ } |
| Coxeter diagram | ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
| Cells | 8{4,3} |
| Faces | 24{4} |
| Edges | 32 |
| Vertices | 16 |
| Vertex figure | Tetrahedron |
| Petrie polygon | octagon |
| Coxeter group | B4, [3,3,4] |
| Dual | 16-cell |
| Properties | convex,isogonal,isotoxal,isohedral,Hanner polytope |
| Uniform index | 10 |
Ingeometry, atesseract or4-cube is afour-dimensionalhypercube, analogous to a two-dimensionalsquare and a three-dimensionalcube.[1] Just as the perimeter of the square consists of four edges and the surface of the cube consists of six squarefaces, thehypersurface of the tesseract consists of eight cubicalcells, meeting atright angles. The tesseract is one of the sixconvex regular 4-polytopes.
The tesseract is also called an8-cell,C8, (regular)octachoron, orcubic prism. It is the four-dimensionalmeasure polytope, taken as a unit for hypervolume.[2] Coxeter labels it theγ4 polytope.[3] The termhypercube without a dimension reference is frequently treated as a synonym for this specificpolytope.
TheOxford English Dictionary traces the wordtesseract toCharles Howard Hinton's 1888 bookA New Era of Thought. Hinton originally spelled the word astessaract,[4] changing it totesseract in his 1904 bookThe Fourth Dimension. The term derives from the Greektéssara (τέσσαρα 'four') andaktís (ἀκτίς 'ray'), referring to the four edges from each vertex to other vertices.
The construction of a tesseract can be visualized through the analogy of dimensions in the following steps:
For a tesseract, it is bounded by eight cubes that are known as thecells, each pair of which intersects, forming twenty-four square faces. Three cubes and three squares intersect at each edge. Four cubes, six squares, and four edges meet at every vertex. Collectively, the tesseract consists of eight cubes, twenty-four squares, thirty-two edges, and sixteen vertices. The tesseract, as well as both the square and the cube, is a member of thehypercube's family.[5]
An unfolding of apolytope is called anet. There are 261 distinct nets of the tesseract.[6] The unfoldings of the tesseract can be counted by mapping the nets topaired trees (atree together with aperfect matching in itscomplement), which can tile 3-space.[7] TheDali cross is one of the net examples, named after Spanish surrealist artistSalvador Dalí, whose paintingCorpus Hypercubus in 1954. It is constructed from eight cubes, whereby four cubes are stacked vertically, and four others are attached to the second-from-top cube of the stack.[8][9]
The eight cells of a tesseract may be regarded in three different ways as two interlocked rings of four cubes.[10] As aregular polytope with threecubes folded together around every edge, it hasSchläfli symbol {4,3,3} withhyperoctahedral symmetry of order 384. Constructed as a 4Dhyperprism made of two parallel cubes, it can be named as a composite Schläfli symbol {4,3} × { }, with symmetry order 96. As a 4-4duoprism, aCartesian product of twosquares, it can be named by a composite Schläfli symbol {4}×{4}, with symmetry order 64. As anorthotope it can be represented by composite Schläfli symbol { } × { } × { } × { } or { }4, with symmetry order 16.
Since each vertex of a tesseract is adjacent to four edges, thevertex figure of the tesseract is a regulartetrahedron. Thedual polytope of the tesseract is the16-cell with Schläfli symbol {3,3,4}, with which it can be combined to form the compound of tesseract and 16-cell.
Each edge of a regular tesseract is of the same length. This is of interest when using tesseracts as the basis for anetwork topology to link multiple processors inparallel computing: the distance between two nodes is at most 4 and there are many different paths to allow weight balancing.
The tesseract can be decomposed into smaller 4-polytopes. It is the convex hull of the compound of twodemitesseracts (16-cells). It can also betriangulated into 4-dimensionalsimplices (irregular 5-cells) that share their vertices with the tesseract. It is known that there are92487256 such triangulations[11] and that the fewest 4-dimensional simplices in any of them is 16.[12]
The dissection of the tesseract into instances of itscharacteristic simplex (a particularorthoscheme with Coxeter diagram





) is the most basic direct construction of the tesseract possible. Thecharacteristic 5-cell of the 4-cube is afundamental region of the tesseract's definingsymmetry group, the group which generates theB4 polytopes. The tesseract's characteristic simplex directlygenerates the tesseract through the actions of the group, by reflecting itself in its own bounding facets (itsmirror walls).
Aunit tesseract has side length1, and is typically taken as the basic unit forhypervolume in 4-dimensional space.The unit tesseract in aCartesian coordinate system for 4-dimensional space has two opposite vertices at coordinates[0, 0, 0, 0] and[1, 1, 1, 1], and other vertices with coordinates at all possible combinations of0s and1s. It is theCartesian product of the closedunit interval[0, 1] in each axis.
Sometimes a unit tesseract is centered at the origin, so that its coordinates are the more symmetrical This is the Cartesian product of the closed interval in each axis.
Another commonly convenient tesseract is the Cartesian product of the closed interval in each axis, with vertices at coordinates. This tesseract has side length 2 and hypervolume.[13]
The radius of ahypersphere circumscribed about a regular polytope is the distance from the polytope's center to one of the vertices, and for the tesseract this radius is equal to its edge length; the diameter of the sphere, the length of the diagonal between opposite vertices of the tesseract, is twice the edge length. Only a few uniformpolytopes have this property, including the four-dimensional tesseract and24-cell, the three-dimensionalcuboctahedron, and the two-dimensionalhexagon. In particular, the tesseract is the only hypercube (other than a zero-dimensional point) that isradially equilateral. The longest vertex-to-vertex diagonal of an-dimensional hypercube of unit edge length is which for the square is for the cube is and only for the tesseract is edge lengths.
An axis-aligned tesseract inscribed in a unit-radius 3-sphere has vertices with coordinates

For a tesseract with side lengths:
Thisconfiguration matrix represents the tesseract. The rows and columns correspond to vertices, edges, faces, and cells. The diagonal numbers say how many of each element occur in the whole tesseract. The diagonal reduces to thef-vector (16,32,24,8).
The nondiagonal numbers say how many of the column's element occur in or at the row's element.[14] For example, the 2 in the first column of the second row indicates that there are 2 vertices in (i.e., at the extremes of) each edge; the 4 in the second column of the first row indicates that 4 edges meet at each vertex.
The bottom row defines they facets, here cubes, have f-vector (8,12,6). The next row left of diagonal is ridge elements (facet of cube), here a square, (4,4).
The upper row is the f-vector of thevertex figure, here tetrahedra, (4,6,4). The next row is vertex figure ridge, here a triangle, (3,3).
It is possible to project tesseracts into three- and two-dimensional spaces, similarly to projecting a cube into two-dimensional space.


Thecell-first parallelprojection of the tesseract into three-dimensional space has acubical envelope. The nearest and farthest cells are projected onto the cube, and the remaining six cells are projected onto the six square faces of the cube.
Theface-first parallel projection of the tesseract into three-dimensional space has acuboidal envelope. Two pairs of cells project to the upper and lower halves of this envelope, and the four remaining cells project to the side faces.
Theedge-first parallel projection of the tesseract into three-dimensional space has an envelope in the shape of ahexagonal prism. Six cells project onto rhombic prisms, which are laid out in the hexagonal prism in a way analogous to how the faces of the 3D cube project onto six rhombs in a hexagonal envelope under vertex-first projection. The two remaining cells project onto the prism bases.
Thevertex-first parallel projection of the tesseract into three-dimensional space has arhombic dodecahedral envelope. Two vertices of the tesseract are projected to the origin. There are exactly two ways ofdissecting a rhombic dodecahedron into four congruentrhombohedra, giving a total of eight possible rhombohedra, each a projectedcube of the tesseract. This projection is also the one with maximal volume. One set of projection vectors areu = (1,1,−1,−1),v = (−1,1,−1,1),w = (1,−1,−1,1).

| Coxeter plane | B4 | B4 --> A3 | A3 |
|---|---|---|---|
| Graph | |||
| Dihedral symmetry | [8] | [4] | [4] |
| Coxeter plane | Other | B3 / D4 / A2 | B2 / D3 |
| Graph | |||
| Dihedral symmetry | [2] | [6] | [4] |
![]() A 3D projection of a tesseract performing asimple rotation about a plane in 4-dimensional space. The plane bisects the figure from front-left to back-right and top to bottom. | ![]() A 3D projection of a tesseract performing adouble rotation about two orthogonal planes in 4-dimensional space. |
Perspective withhidden volume elimination. The red corner is the nearest in4D and has 4 cubical cells meeting around it. |
Thetetrahedron forms theconvex hull of the tesseract's vertex-centered central projection. Four of 8 cubic cells are shown. The 16th vertex is projected toinfinity and the four edges to it are not shown. | Stereographic projection (Edges are projected onto the3-sphere) |
Stereoscopic 3D projection of a tesseract (parallel view) |
Stereoscopic 3D DisarmedHypercube |
The tesseract, like allhypercubes,tessellatesEuclidean space. The self-dualtesseractic honeycomb consisting of 4 tesseracts around each face hasSchläfli symbol{4,3,3,4}. Hence, the tesseract has adihedral angle of 90°.[15]
The tesseract'sradial equilateral symmetry makes its tessellation theunique regular body-centered cubic lattice of equal-sized spheres, in any number of dimensions.
The tesseract is 4th in a series ofhypercube:
| Line segment | Square | Cube | 4-cube | 5-cube | 6-cube | 7-cube | 8-cube | 9-cube | 10-cube |
The tesseract (8-cell) is the third in the sequence of 6 convex regular 4-polytopes (in order of size and complexity).
| Regular convex 4-polytopes | |||||||
|---|---|---|---|---|---|---|---|
| Symmetry group | A4 | B4 | F4 | H4 | |||
| Name | 5-cell Hyper-tetrahedron | 16-cell Hyper-octahedron | 8-cell Hyper-cube | 24-cell
| 600-cell Hyper-icosahedron | 120-cell Hyper-dodecahedron | |
| Schläfli symbol | {3, 3, 3} | {3, 3, 4} | {4, 3, 3} | {3, 4, 3} | {3, 3, 5} | {5, 3, 3} | |
| Coxeter mirrors | ![]() ![]() ![]() ![]() ![]() ![]() ![]() | ![]() ![]() ![]() ![]() ![]() ![]() ![]() | ![]() ![]() ![]() ![]() ![]() ![]() ![]() | ![]() ![]() ![]() ![]() ![]() ![]() ![]() | ![]() ![]() ![]() ![]() ![]() ![]() ![]() | ![]() ![]() ![]() ![]() ![]() ![]() ![]() | |
| Mirror dihedrals | 𝝅/3𝝅/3𝝅/3𝝅/2𝝅/2𝝅/2 | 𝝅/3𝝅/3𝝅/4𝝅/2𝝅/2𝝅/2 | 𝝅/4𝝅/3𝝅/3𝝅/2𝝅/2𝝅/2 | 𝝅/3𝝅/4𝝅/3𝝅/2𝝅/2𝝅/2 | 𝝅/3𝝅/3𝝅/5𝝅/2𝝅/2𝝅/2 | 𝝅/5𝝅/3𝝅/3𝝅/2𝝅/2𝝅/2 | |
| Graph | |||||||
| Vertices | 5 tetrahedral | 8 octahedral | 16 tetrahedral | 24 cubical | 120 icosahedral | 600 tetrahedral | |
| Edges | 10 triangular | 24 square | 32 triangular | 96 triangular | 720 pentagonal | 1200 triangular | |
| Faces | 10 triangles | 32 triangles | 24 squares | 96 triangles | 1200 triangles | 720 pentagons | |
| Cells | 5 tetrahedra | 16 tetrahedra | 8 cubes | 24 octahedra | 600 tetrahedra | 120 dodecahedra | |
| Tori | 15-tetrahedron | 28-tetrahedron | 24-cube | 46-octahedron | 2030-tetrahedron | 1210-dodecahedron | |
| Inscribed | 120 in 120-cell | 675 in 120-cell | 2 16-cells | 3 8-cells | 25 24-cells | 10 600-cells | |
| Great polygons | 2squares x 3 | 4 rectangles x 4 | 4hexagons x 4 | 12decagons x 6 | 100irregular hexagons x 4 | ||
| Petrie polygons | 1pentagon x 2 | 1octagon x 3 | 2octagons x 4 | 2dodecagons x 4 | 430-gons x 6 | 2030-gons x 4 | |
| Long radius | |||||||
| Edge length | |||||||
| Short radius | |||||||
| Area | |||||||
| Volume | |||||||
| 4-Content | |||||||
As a uniformduoprism, the tesseract exists in asequence of uniform duoprisms: {p}×{4}.
The regular tesseract, along with the16-cell, exists in a set of 15uniform 4-polytopes with the same symmetry. The tesseract {4,3,3} exists in asequence of regular 4-polytopes and honeycombs, {p,3,3} withtetrahedralvertex figures, {3,3}. The tesseract is also in asequence of regular 4-polytope and honeycombs, {4,3,p} withcubiccells.
| Orthogonal | Perspective |
|---|---|
| 4{4}2, with 16 vertices and 8 4-edges, with the 8 4-edges shown here as 4 red and 4 blue squares | |
Theregular complex polytope4{4}2,

, in has a real representation as a tesseract or 4-4duoprism in 4-dimensional space.4{4}2 has 16 vertices, and 8 4-edges. Its symmetry is4[4]2, order 32. It also has a lower symmetry construction,

, or4{}×4{}, with symmetry4[2]4, order 16. This is the symmetry if the red and blue 4-edges are considered distinct.[16]
Since their discovery, four-dimensional hypercubes have been a popular theme in art, architecture, and science fiction. Notable examples include:
The wordtesseract has been adopted for numerous other uses in popular culture, including as a plot device in works of science fiction, often with little or no connection to the four-dimensional hypercube; seeTesseract (disambiguation).
| Line segment | Square | Cube | 4-cube | 5-cube | 6-cube | 7-cube | 8-cube | 9-cube | 10-cube |