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Vi Hart has 3D printed a hypercube made of monkeys that has the symmetries of the Quaternion group

Group theorists, often interested principally in the abstract, have been known to neglect the vital importance of producing funky gizmos that exhibit the symmetries they have theorized about. Internet maths celeb Vi Hart, working with mathematician Henry Segerman, has addressed this absence in the case of $Q_8$, the quaternion group. The object they’ve designed is four-dimensional and made of monkeys, and they’ve done the closest thing possible to making one, which is to 3D-print an embedding of it into our three-dimensional universe, also made of monkeys. Their ArXiv preprint (pdf) is well worth a read, and when you get to the photos of the resulting sculpture (entitled “More fun than a hypercube of monkeys”), you’ll fall off your chair.

Further reading

The Quaternion Group as a Symmetry Group by Vi Hart and Henry Segerman, on the ArXiv.

Nothing Is More Fun than a Hypercube of Monkeys at Roots of Unity, including an animated gif of a virtual version of the sculpture rotating through 4D-space.

Henry Segerman’s homepage

Vi Hart’s home page

3D-printed mathematical objects roundup

3D printers are ace. People are using them to make all sorts of cool things. If you can describe a shape to a computer, it’s very easy to send that description to a 3D printer, which will happily smoosh some substrates together to make a real model of your shape. Mathematicians are able to describe all sorts of crazy shapes, in exactly the amount of detail computers need, so they’ve taken to 3D printing like ducks to water.

Thingiverse is just a repository for designs, so if you see something you like you’ll have to find your own 3D printer. Shapeways makes the objects and posts them to you; prices can vary from just a few euros to hundreds, depending on the size of the object and the materials used.

As with all other kinds of mathematical art, there’s a huge amount of repetition of the same few ideas, but also a few really interesting and unique designs. I’ve picked a couple of representatives from each of the popular topics, but do search around if you want a version with slightly different parameters; you’re bound to find something suitable.

For the past few months I’ve been quietly compiling a list of interesting mathematical objects I’ve found on the main 3D printing catalogues, Thingiverse and Shapeways. With Christmas approaching, I thought now would be as good a time as any to share what I’ve found.

Henry Segerman’s 30-cell puzzle

Henry Segerman is a mathematician at the University of Melbourne with a keen interest in 3d-printing mathematical shapes. He’s just uploaded a video showing off his latest creation, a 30-cell burr puzzle created in collaboration with Saul Schleimer:

[youtube url=https://www.youtube.com/watch?v=FJwqT_sbB_A]

Pretty cool, eh?

As well as providing a PDF describing the puzzle, Henry’s uploaded the design to Shapeways so you can have your very own copy to play with.

Earlier this year, Henry and Saul’s half 120- and 600-cells won the “Best Use of Mathematics” award at the 2012 Bridges Conference.