We started off with two great plenary talks at Bridges: George Hart on AI and math art, and @ayliean.bsky.social on time. I especially loved her musing about the act of making art being the point—illustrated by her many varied ways of drawing an identical grid of squares.

More math tourism: the library at Trinity College Dublin. Now with busts of female scholars, like Ada Lovelace (2023).

Math tourism: Broome Bridge in Dublin, Ireland, where Hamilton discovered the quaternions!

The font was small, I was lazy, and I didn't want to count all the 1s. I copied and pasted into Google: "What is the number 1111111111?" Not the reply I expected.

Benefit of having tenure and being at this stage in my career: spending days working on a problem, forming conjectures, finding connections, making discoveries, and proving results, all while not ruining the fun by doing a literature search to see if it is new. (If not, bummer, but it was worth it!)

Lovely article in the NY Times. Too bad there was no mention of Euler's polyhedron formula. 😀 www.nytimes.com/2026/07/17/s...

A Mathematical Tribute to the Soccer Ball

As the World Cup final approaches, take a moment to appreciate the beautiful symmetries of humanity’s favorite truncated icosahedron.

nytimes.com

@courtneygibbons.phd I just saw in a Hamilton College social media post that you were promoted to full professor. Congratulations!!

I created this logic/grid deduction puzzle several months ago just to try out vibe coding. I created it for myself and have been enjoying playing it, so I thought I'd share it more widely. I call it Daedalus' Labyrinth. divisbyzero.github.io/Daedalus-Lab... Each segment in the grid must either

Who says AI is not useful? Here's today's use case. 🤣🤣🤣 This was my Facebook memory from 15 years ago. (I still think it is funny!) "We just bought this juice today. I don't understand what the '100%' refers to. 100% cranberry juice: no. 100% juice: no. All I can figure is 100% blend. But isn't

I made these card suits using curved origami techniques.

It is definitely worth watching this entire video! My friend and colleague, @allthingsphysics.bsky.social shows how you can "hear light"! (It is also fun to see cameo appearances of other friends, colleagues, and students who are wowed by this effect!) www.youtube.com/watch?v=tthv...

How to hear light!

YouTube video by All Things Physics

youtube.com

Over 5,500 mathematical artworks can now be browsed in an attractive new gallery-wall layout on the Bridges website, thanks to the efforts of Nathan Selikoff: gallery.bridgesmathart.org/gallery?seed...

Happy Fourth of July! This is Old West on the campus of Dickinson College lit up for the 250th birthday celebration.

While watching the World Cup: Making a curved origami fish and cat.

I folded this star shape. Is this a known origami pattern?

On a whim, I asked Claude to make one of those D&D alignment charts filled with historical math figures. Here's what it gave me. I then asked it to redo the activity, but to add some diversity—women, non-Europeans, etc. What do you think?

I got 18/20. I got one of the constitutional amendment questions wrong, and I thought the Statue of Liberty question was a trick question (LOL!). www.washingtonpost.com/nation/inter...

Can you pass this quiz on American history and government?

As we celebrate the nation’s 250th birthday, test your civics knowledge and see how your score compares to others.

washingtonpost.com

fixed your headline

Nick (derogatory) ✨@slothropsmap.bsky.social · last mo.

They’re calling it the least comprehensible achievement of all time.

Serious question: Is "parabolic" now being used in this way in everyday language, like "exponential" is traditionally, to mean rapid growth? Being a New Yorker comic, I suspect it passed by competent editors and wasn't an error that slipped through.

The proceedings for the Bridges 2026 conference in Galway (August 4-8) are out! I'm very excited to go. My article in this volume is an update of an older article I wrote: "A New Method for Creating Impossible Cylinders" archive.bridgesmathart.org/2026/

The proceedings of the Bridges Math Art conference were published online a couple of days ago: https://archive.bridgesmathart.org/2026/ This is always a highlight of the year for me; but especially so this year, because they contain a paper that I co-wrote! So I thought I would say a bit about […]

We were in an Uber at about 11:00 last night at a stoplight and saw a drunk driver take a turn so sharp that they were 100% on the opposite sidewalk, hit this light post, and kept driving. No brake lights before, during, or after the collision. Terrifying. It was too dark and too far away for us

Here are a few more curved origami pieces I made. Technically, I made them so the crease lies in the same plane. But if I make the strips narrow enough relative to the object's size, you can get the over-and-under behavior to work pretty well. I could have made all of these except the 5₁ knot

Today I learned that John Milnor was a college freshman (17 years old?) when he proved that every nontrivial knot must have total curvature greater than 4π. It was published in the Annals of Math. It is now known as the Fáry-Milnor theorem (since it was proved independently by Fáry).

I just started listening to the audiobook for A Beautiful Mind. I'm hoping John von Neumann is a relatively minor character, because I can't take too many of these "von Newman" pronunciations.

Two different figure-eight knots made with curved origami. The blue one has a fold angle of 90°, and the purple has a fold angle of 60°. The latter can be made with one strip of paper. The former required two.

This is a big deal. It’s been an open question whether even billiards in a triangle always has a periodic orbit. Not surprised that all polygons would fall at once, however. The methods don’t even look too intimidating. Need to study this more carefully!

arxiv math.DS@arxiv-math-ds.bsky.social · 2mo ago

Giovanni Forni Existence of a Periodic Orbit for Billiards in Polygons https://arxiv.org/abs/2606.10102

Here are a few more curved origami pieces. I've been reading _Curved-Folding Origami Design_ by Jun Mitani. The treble clef is his design. The trefoil is mine. I made the others, but they were based on photos in his book.

Today I was reading about and playing with curved origami. Here's what I designed and made. It is cool how folding along the curve changes the shape of the object (like the M → ❤️).

Borromean carabiners and Borromean paper clips.