## Video URL

http://pirsa.org/23020056# The Tenfold Way

### APA

Baez, J. (2023). The Tenfold Way. Perimeter Institute for Theoretical Physics. http://pirsa.org/23020056

### MLA

Baez, John. The Tenfold Way. Perimeter Institute for Theoretical Physics, Feb. 15, 2023, http://pirsa.org/23020056

### BibTex

@misc{ scitalks_23020056, doi = {}, url = {http://pirsa.org/23020056}, author = {Baez, John}, keywords = {Other Physics}, language = {en}, title = {The Tenfold Way}, publisher = {Perimeter Institute for Theoretical Physics}, year = {2023}, month = {feb}, note = {Talk #23020056 see, \url{https://scitalks.ca}} }

John Baez University of California System

## Abstract

The importance of the tenfold way in physics was only recognized in this century. Simply put, it implies that there are ten fundamentally different kinds of matter. But it goes back to 1964, when the topologist C. T. C. Wall classified the associative real super division algebras and found ten of them. The three 'purely even' examples were already familiar: the real numbers, complex numbers and quaternions. The rest become important when we classify representations of groups on Z/2-graded Hilbert spaces. We explain this classification, its connection to Clifford algebras, and some of its implications.

Zoom Link: https://pitp.zoom.us/j/96451287888?pwd=dlp2eVhKVTU0L2hqN2UxMy95V21SQT09