Quaternion Algebras

One of perks of PhD of quantum physics is that quaternions get mundane, vide https://en.wikipedia.org/wiki/Pauli_matrices. SU(2) is everywhere (normalized quaternions). These are are more common than regular rotations of 3D space, O(3).

Because SU(2) we get a lot of interesting phenomena, including that there are two types of particles, bosons and fermions. We get some interesting phenomena that only rotating by 720deg (two full rotations) bring back to the initial state. And I am not talking only about USB-A, but about spinors (https://en.wikipedia.org/wiki/Spinor) - there are some party tricks around that (vide https://www.reddit.com/r/physicsmemes/comments/181oldw/a_ger...).

I like quaternions as much as the next guy (I’ve used them in numerical computations etc), but what is it about them that makes them show up on the front page every few weeks?

the late Doug Sweetser had in the 90s a website where he used quaternions (and quaternion analysis) for describing physics from his viewpoint. it was quit interesting. he had several github repositories [0] where he described his ideas. worth a look [0] https://github.com/dougsweetser?tab=repositories

average period between quaternion posts what about kalman filters?