Community Event / Creation Ancient alien architecture part 2: 4-dimensional polytopes

This is a followup to my previous post, which was about lattices in 3-dimensional Euclidean space, used as alien artifacts. This one is about "lattices" in 3-dimensional spherical space (sometimes called the 3-sphere), which is the unit sphere in 4-dimensional Euclidean space. A 3-dimensional polyhedron can be drawn like a beach ball on the surface of an ordinary sphere (mathematicians call this the 2-sphere) in 3D space, which gives a "lattice-like" structure on the sphere. Similarly, 4D polytopes (the analogues of the 3-dimensional polyhedra) give a lattice-like structure on the 3-sphere. Then we can draw these things back in 3-dimensional Euclidean space using something called stereographic projection.

Ok anyway, enough theory, what do these look like?

tesseract_montage.jpg


WebGL rotatable model.

This is the hypercube, the 4-dimensional version of the cube. In 3D the cube is one of five regular polyhedra (the others being the tetrahedron, octahedron, dodecahedron and icosahedron, or in this crowd I suspect, the d4, d8, d12 and d20). In 4D there are 6 regular polytopes. Here are a couple of them, the 24-cell and the 120-cell:

24-cell_montage.jpg


WebGL rotatable model.

Here is the 120-cell, which as it's name suggests, has 120 dodecahedral cells:

120-cell_montage.jpg


WebGL rotatable model.

These might be good things to put wormholes or gates etc. at the center of.

Finally, I had to figure out what the 4-dimensional version of the Coriolis station would be. The Coriolis station is in the shape of a cuboctahedron, which in some sense is half way between the cube and the octahedron. The 4-dimensional version of the cube is the hypercube, and the 4-dimensional version of the octahedron is the 16-cell, so the thing that is half way between those two is something called the "bitruncated tesseract":

bitruncated_tesseract_montage.jpg


WebGL rotatable model.

There is however an alternative, something called the "rectified tesseract". This has the advantage of having cuboctahedra inside it!

rectified_tesseract_montage.jpg


WebGL rotatable model.
 
I can hear my graphics card fan spinning up in expectation of rendering those things!

You certainly couldn't have an attack fleet of those things - not for a good few years at least.
 
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