What a beautiful subject. A framework that manages to incorporate the complex numbers, quaternions, and vector algebra - all from a unified perspective. Is there a textbook that uses this framework to present “all of physics,” similarly to what you can find for some other frameworks (e.g. Lie groups/algebras)?
Looks interesting, thanks. (Too bad, as one of the reviewers notes, “author has given up on theoretical physics and now runs a software development company specializing in lighting/shading routines for video games”...)
Chris Doran, while not officially in academia, is still very much actively researching these topics and regularly publishes. (he is also a member of the bivector community, very approachable and happy to help out with questions).
Anthony Lasenby, professor astrophysics and cosmology at Cambridge, is also absolutely still actively researching and publishing, all in the mindset of the GA4Physicists book. (See a recent (feb 2020) lecture of him here : https://www.youtube.com/watch?v=x7eLEtmq6PY&t=7s )
(GA4P is considered one of the few comprehensive and up to date treatments of geometric algebra, not just in physics).
As a school kid (14? 15?), I won a prize to go to Birmingham University (UK) each Saturday morning for a term, to do a maths course. The teachers took turns in taking me and another to the course. One of the things I remember doing was playing with all kinds of geometrical transformations of triangles (e.g. bisect each of the edges to get the circumcentre and then add a circle which had that centre. As you adjusted the shape of the triangle everything updated in real time). It was running on what must have been a mainframe. This was my first (and only?) experience of using a mainframe. I remember being rather unimpressed with the mainframe, since it hung and crashed once. The interface was also a bit crap. As all of the students started doing this work, the mainframe started to struggle and slow down! These libraries look to be able to do similar stuff which is very cool.
I had fond memories of that, and was a reason I got into Computer Science and Maths. I wanted to recreate it, but I've never really tried to do it. These libs look like they could be just the thing.
> As you adjusted the shape of the triangle everything updated in real time). It was running on what must have been a mainframe.
I think it was probably a minicomputer, not a mainframe. Good interactivity was pioneered by minicomputers and traditionally not associated with mainframes.
Grassmann.jl (features on bivector.net)
https://github.com/chakravala/Grassmann.jl