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If you’re wanting to learn some applied category theory, register for the tutorials that are taking place on July 5, 2020 as part of ACT2020! Applied category theory offers a rigorous mathema… | Continue reading
Due to the coronavirus outbreak, many universities are moving activities online. This is a great opportunity to open up ACT2020 to a broader audience, with speakers from around the world. The confe… | Continue reading
Here’s a fun challenge for people confined due to coronavirus. The E8 lattice is a thing of beauty, taking full advantage of the magic properties of the number 8. The octahedron has 8 sides. … | Continue reading
If you click on this picture, you’ll see a zoomable image of the Milky Way with 84 million stars: But stars contribute only a tiny fraction of the total entropy in the observable Universe. If… | Continue reading
A slightly different version of this article I wrote first appeared in Nautilus on November 28, 2019. Water rushes into Venice’s city council chamber just minutes after the local government rejects… | Continue reading
Schrödinger and Einstein helped invent quantum mechanics. But they didn’t really believe in its implications for the structure of reality, so in their later years they couldn’t … | Continue reading
You probably that planets go around the sun in elliptical orbits. But do you know why? In fact, they’re moving in circles in 4 dimensions. But when these circles are projected down to 3-dimen… | Continue reading
Here’s the first of a series of blog articles on how technology can help address climate change: • Adam Marblestone, Climate technology primer (1/3): basics. Adam Marblestone is a research sc… | Continue reading
I wrote something for the Spanish newspaper El País, which has a column on mathematics called “Café y Teoremas”. Ágata Timón helped me a lot with writing this, and she also translated i… | Continue reading
About 1/3 of the meteorites hitting Earth today come from one source: the L chondrite parent body, an asteroid 100–150 kilometers across that was smashed in an impact 468 million years ago. T… | Continue reading
Izabella Łaba is a mathematician at the University of British Columbia. She works on harmonic analysis, geometric measure theory and additive combinatorics. But this talk is on a different topic: •… | Continue reading
I’m going to try to post more short news items. For example, here’s a new book I haven’t read yet: • Naomi Klein, On Fire: The (Burning) Case for a Green New Deal, Simon and Schus… | Continue reading
The complex numbers together with infinity form a sphere called the Riemann sphere. The 6 simplest numbers on this sphere lie at points we could call the north pole, the south pole, the east pole, … | Continue reading
This is part 4 of an intermittent yet always enjoyable series: • Part 1: the rise of the ancient Puebloan civilization in the American Southwest from 10,000 BC to 750 AD. • Part 2: the rise and col… | Continue reading
Check out the video of Christian Williams’’s talk in the Applied Category Theory Seminar here at U. C. Riverside. It was nicely edited by Paola Fernandez and uploaded by Joe Moeller. A… | Continue reading
If you take the entries Pascal’s triangle mod 2 and draw black for 1 and white for 0, you get a pleasing pattern: The $latex 2^n$th row consists of all 1’s. If you look at the triangle … | Continue reading
Yay! David Spivak and Brendan Fong are teaching a course on applied category theory based on their book, and the lectures are on YouTube! Here are the first two videos: Their book is free here: &bu… | Continue reading
Abstract. The global warming crisis is part of a bigger transformation in which humanity realizes that the Earth is a finite system and that our population, energy usage, and the like cannot contin… | Continue reading
In this century, progress in fundamental physics has been slow. The Large Hadron Collider hasn’t yet found any surprises, attempts to directly detect dark matter have been unsuccessful, strin… | Continue reading
We’re going to have a seminar on applied category theory here at U. C. Riverside! My students have been thinking hard about category theory for a few years, but they’ve decided it’… | Continue reading
I have predicted for a while that as the issue of climate change becomes ever more urgent, the public attitude regarding geoengineering will at some point undergo a phase transition. For a long tim… | Continue reading
Here’s a draft of a little thing I’m writing for the Newsletter of the London Mathematical Society. The regular icosahedron is connected to many ‘exceptional objects’ in mat… | Continue reading
I’m teaching a course on category theory at U.C. Riverside, and since my website is still suffering from reduced functionality I’ll put the course notes here for now. I taught an introd… | Continue reading
This is a well-known, easy group theory result that I just learned. I would like to explain it more slowly and gently, and I hope memorably, than I’ve seen it done. It’s called the 5/8 … | Continue reading
Sometimes patterns can lead you astray. For example, it’s known that $latex \displaystyle{ \mathrm{li}(x) = \int_0^x \frac{dt}{\ln t} }$ is a good approximation to $latex \pi(x),$ the number … | Continue reading
Jade Master and I have just finished a paper on open Petri nets: • John Baez and Jade Master, Open Petri nets. Abstract. The reachability semantics for Petri nets can be studied using open Pet… | Continue reading
Last time we saw that if you randomly choose two points on the unit sphere in 1-, 2- or 4-dimensional space and look at the probability distribution of their distances, then the even moments of thi… | Continue reading
John D. Cook, Greg Egan, Dan Piponi and I had a fun mathematical adventure on Twitter. It started when John Cook wrote a program to compute the probability distribution of distances $latex |xy R… | Continue reading
Big news! An experiment called MiniBooNE at Fermilab in Chicago has found more evidence that neutrinos are not acting as the Standard Model says they should: • The MiniBooNE Collaboration, Obs… | Continue reading
guest post by Christian Williams Mike Stay has been doing some really cool stuff since earning his doctorate. He’s been collaborating with Greg Meredith, who studied the π-calculus wi… | Continue reading
guest post by Matteo Polettini Suppose you receive an email from someone who claims “here is the project of a machine that runs forever and ever and produces energy for free!” Obviously… | Continue reading