Today I heard from David Benson that Jack Morava died yesterday. This comes as such a huge shock that I can’t help but hope Benson was somehow misinformed. Morava has been posting comments to the ...

August 2025's Entries (BT) Diversity from (LC) Diversity Jack Morava Random Past Entries TeXnical Issues Sage advice on viewing this blog and posting comments thereon. Categories, Logic and Physics in ...

Announcing the Clowder Project: a wiki and reference work for category theory built using the same general infrastructure and tag system of the Stacks Project.

Note: These pages make extensive use of the latest XHTML and CSS Standards. They ought to look great in any standards-compliant modern browser. Unfortunately, they will probably look horrible in older ...

Quick question. Classically the harmonic oscillator Hamiltonian is often written 1 2 ( p 2 + q 2), while quantum mechanically it gets some extra ‘ground state energy’ making the Hamiltonian ...

guest post by Paolo Perrone On this blog there has been quite a number of posts about the interaction of category theory and probability (for example here, here, here, and here), as well as about ...

In Part 1, I explained my hopes that classical statistical mechanics reduces to thermodynamics in the limit where Boltzmann’s constant k k approaches zero. In Part 2, I explained exactly what I mean ...

For questions 1 and 2, isn’t that true for any group G, not just the fundamental groups of a manifold? And moreover, I think of this as the definition of the profinite completion of a group: as an ...

Last time I reviewed a bit of Bott periodicity. Now I want to start leading up to a question about it. It will take a while. So, this time, I will explain a wonderful one-to-one correspondence between ...

We discuss in this post how these questions led us to possible relations to information geometry. We would love to hear from you: Is magnitude an interesting invariant for information geometry? Is ...

Today we’ll be talking about the theory of universal algebra, and its less well-known counterpart of universal coalgebra. We’ll try to convince you that these two frameworks provide us with suitable ...

Next: Part 2 In this post and the next, I want to try out a new idea and see where it leads. It goes back to where magnitude began, which was the desire to unify elementary counting formulas like the ...