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24-cell

math Maturity 7-9

Some shapes live in a new way.

24-cell.gif
24-cell.gif
They have many sides. This one has twenty-four parts. It is a very special shape. It helps us learn about space. Can you see its parts move?
24-cell-orig.gif
24-cell-orig.gif

36 words

Imagine a shape with many parts.

24-cell.gif
24-cell.gif
This shape is called a 24-cell. It lives in a space with four parts. It is made of 24 special blocks. Each block is an octahedron.
Octahedron.png
Octahedron.png
An octahedron has eight sides. This big shape has 24 corners. It also has 96 edges. These edges are straight lines. It is a very special shape. It can even fit together like tiles.
Icositetrachoronic tetracomb.png
Icositetrachoronic tetracomb.png
This helps us see how shapes work in space.

79 words

Imagine a shape that lives in four dimensions.

24-cell.gif
24-cell.gif
We call this shape the 24-cell. It is a very special type of object. In math, we call it a regular 4-polytope. This means all its parts are the same.
Octahedron.png
Octahedron.png
The 24-cell is made of 24 small blocks. Each block is an octahedron. An octahedron is a shape with eight sides. The 24-cell has 24 corners and 96 edges. It also has 96 flat faces. These faces are all triangles. This shape is very unique. It is one of only six regular shapes in four dimensions.
Icositetrachoronic tetracomb.png
Icositetrachoronic tetracomb.png
The 24-cell can even fill up space. It can fit together perfectly like tiles on a floor. This is called a honeycomb. When 24-cells join together, they share their sides. This helps math experts study how shapes work in high dimensions. It is a beautiful and complex part of geometry.

148 words

Imagine a shape that lives in four dimensions.

24-cell.gif
24-cell.gif
We call this shape the 24-cell. It is a very special type of object called a regular 4-polytope. This means all its parts are exactly the same. It is a shape that exists beyond the three dimensions we see every day.
Octahedron.png
Octahedron.png
The 24-cell is built from 24 smaller shapes called octahedral cells. An octahedron is a solid shape with eight triangular faces. In this four-dimensional shape, these octahedra join together in a very precise way. It is a beautiful example of how math creates order in high dimensions.

To understand how it works, we can look at its parts. The 24-cell has 24 vertices, which are its corners. It also has 96 edges and 96 triangular faces.

24-cell-6 ring edge center perspective.png
24-cell-6 ring edge center perspective.png
At every vertex, six octahedral cells meet together. At every edge, exactly three cells meet. This specific pattern makes the shape very balanced. It is also self-dual, which is a special math property. This means the shape can be turned into its own twin. This is similar to how a 5-cell works in four dimensions.

Mathematicians use special symbols to describe these complex shapes. The 24-cell has a symbol called {3,4,3}. It also goes by many other names like the icositetrachoron or the octaplex.

OctacCrop.jpg
OctacCrop.jpg
Some people call it the hyper-diamond or the polyoctahedron. It is the fourth shape in a sequence of six regular 4-polytopes. These shapes can be ordered by how much space they fill. The 24-cell is more complex than the tesseract. However, it is smaller and less complex than the 120-cell.

This shape has amazing connections to other parts of math. For example, its 24 vertices can represent something called root vectors.

F4 roots by 24-cell duals.svg
F4 roots by 24-cell duals.svg
These vectors belong to a group called F4. The 24-cell can even be used to build a honeycomb.
Icositetrachoronic tetracomb.png
Icositetrachoronic tetracomb.png
This is a way to tile four-dimensional space perfectly. In this honeycomb, each 24-cell has 24 neighbors. They fit together without leaving any gaps. This makes it a very important tool for studying space.

When the 24-cell rotates, it does something very strange.

24-cell-orig.gif
24-cell-orig.gif
It can perform a double rotation. This means it turns in two different directions at once. In one special kind of rotation, the shape seems to turn inside out. This is called an isoclinic rotation. It can even change its chirality, which is a fancy word for handedness. This is like how a mirror makes your right hand look like a left hand. It is a wonderful way to see how math works in four dimensions.

433 words

{ "text": "The 24-cell is a unique object in four-dimensional geometry. It is classified as a convex regular 4-polytope. This means it is a four-dimensional shape where every part is identical. In three dimensions, we have Platonic solids like the cube. The 24-cell is the four-dimensional analogue of these solids.

24-cell.gif
24-cell.gif
It is often called the icositetrachoron or the octaplex. Other names include the icosatetrahedroid, the octacube, the hyper-diamond, or the polyoctahedron. It is defined by its Schläfli symbol, {3,4,3}. This symbol describes how its components fit together in higher space.\n\nTo understand its structure, we must look at its constituent parts. The 24-cell is composed of 24 octahedral cells. An octahedron is a three-dimensional shape with eight triangular faces.
Octahedron.png
Octahedron.png
These cells connect to form a complex boundary. The shape contains 96 triangular faces and 96 edges. It also has 24 vertices, which are its corner points. At each vertex, exactly six octahedral cells meet. At each edge, three cells meet. The vertex figure, which describes the arrangement around a vertex, is a cube.
24-cell-6 ring edge center perspective.png
24-cell-6 ring edge center perspective.png
\n\nThe 24-cell possesses several rare geometric properties. It is a self-dual polytope. This means its dual shape is identical to itself. Like the 5-cell, it maintains this symmetry. It is also one of only two convex regular 4-polytopes where the edge length equals the radius. The other is the tesseract. Furthermore, the 24-cell is highly inclusive of other geometries. It incorporates the geometries of almost every convex regular polytope in the first four dimensions. It includes all regular polytopes made of triangles and squares, except for the 5-cell. It does not, however, include pentagonal polytopes.\n\nIn the sequence of six convex regular 4-polytopes, the 24-cell holds the fourth position. These shapes can be ordered by their hypervolume, or four-dimensional content, for a given radius. They also nest

304 words
🖼️ Images & Media (16)
File:Octahedron.png
Octahedron.png
File:F4 roots by 24-cell duals.svg
F4 roots by 24-cell duals.svg
File:Binary tetrahedral group elements.png
Binary tetrahedral group elements.png
File:Icositetrachoronic tetracomb.png
Icositetrachoronic tetracomb.png
File:24-cell.gif
24-cell.gif
File:24-cell-orig.gif
24-cell-orig.gif
File:Hopf band wikipedia.png
Hopf band wikipedia.png
File:Regular_star_figure_4(6,1).svg
Regular_star_figure_4(6,1).svg
File:Regular_star_figure_4(3,1).svg
Regular_star_figure_4(3,1).svg
File:Regular_star_figure_2(6,1).svg
Regular_star_figure_2(6,1).svg
File:Regular_polygon_24.svg
Regular_polygon_24.svg
File:Regular_star_figure_12(2,1).svg
Regular_star_figure_12(2,1).svg

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