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Henry Segerman @henryseg@mathstodon.xyz

In the spirit of getting carried away, here is the Making of "The Making of "Peace for Triple Piano"", which describes the making of "The Making of "Peace for Triple Piano"", which describes the making of "Peace for Triple Piano". youtu.be/PDkbk4OILSw

A non-spherical, circular version of “Peace for Triple Piano”, an exploration of symmetry through time and space, with @vihartvihart. youtu.be/g3X0d5NUjjA

The "Making of" video Vi Hart and I made for our space-time symmetry video, "Peace for Triple Piano". youtube.com/watch?v=x1zJoU6Lus

New video with Vi Hart: an exploration of symmetries through space and time, involving a spherical camera, the map z->z³, a piano, Dona nobis pacem, three copies of Vi and two copies of me.

An optical illusion, made with a spherical ("360") camera. With Alexa Meade and Dan Ariely. youtu.be/EahZSQmcs_s mathstodon.xyz/media/TJODzd57-

I have been playing at generating snowflakes using cellular automata.

Just in time for Christmas (if they're into this kind of thing), a new kind of expanding mechanism! shpws.me/Pi30 . More info: youtu.be/bEVHVzrQ_PM

Sneak preview of a mechanism project I’ve been working on for a while.


Stereographic projection of the latitude/longitude grid on the sphere.

Source code: community.wolfram.com/groups/- mathstodon.xyz/media/6W6BEU7iT

New @numberphile video up with me talking about - you guessed it - juggling: youtube.com/watch?v=7dwgusHjA0 - 45 minutes, over 2k views. Wow!

And finally, the dramatic conclusion to my series on Heesch numbers: does there exist a convex pentagon that can be surrounded, but doesn't tile the plane, and admits a surround that's edge-to-edge? Heesch's original 1968 shape does all of the above except the edge-to-edge part. isohedral.ca/heesch-numbers-pa mathstodon.xyz/media/a0bUlDZY_

The story of Heesch numbers continues in two posts. In isohedral.ca/heesch-numbers-pa, I compute Heesch numbers of polyominoes and polyiamonds in search of interesting new examples; in isohedral.ca/heesch-numbers-pa, I present a new family of simple polygons, all with Heesch number 1.

I had to reconstruct this gif by Bill Gosper in GeoGebra to believe it.
Construct the tangent to a given point on a circle without using a compass.

ggbm.at/GJAkqvTb mathstodon.xyz/media/ekv6ASMGa

Matt Parker made a video about our Brilliant Geometry exhibition in Edinburgh: youtube.com/watch?v=LOVzytir7b


Stereographic projection of 30 congruent spheres centered on equally-spaced points along a trefoil knot in the 3-sphere.

Source code: community.wolfram.com/groups/- mathstodon.xyz/media/WZXefyrbf

Topographical topology at the Arches National Park in Utah! youtu.be/-1_VYcJGvKU

Time to justify my presence here...

The Heesch number of a shape is the maximum number of layers of copies of that shape by which you can surround it. Heesch's Problem asks which positive integers can be Heesch numbers. I'll show a few fun new results over a series of blog posts; today, I offer a basic introduction to the topic. isohedral.ca/heesch-numbers-pa