Re: History of string diagrams

[John Baez <baez@math.ucr.edu>]

HI -

Pavel wrote:

> I would like to ask for comments about the history of string diagrams as
> graphical notation for the arrows of higher and monoidal categories.

There's a lot of history in this paper:

John C. Baez and Aaron D. Lauda, A prehistory of n-categorical physics,
in Deep Beauty: Mathematical Innovation and the Search for an Underlying
Intelligibility of the Quantum World, ed. Hans Halvorson, Cambridge U.
Press,
Cambridge, 2011, pp. 13-128.  Also at https://arxiv.org/abs/0908.2469

The most important people in the early history of string diagrams are
Feynman
and Penrose, and I give references and a discussion of their key papers.
Some
of Penrose's papers are a bit hard to find, but he gave me permission to
put them here:

http://math.ucr.edu/home/baez/penrose/

His approach to constructing space from spin networks (a certain kind of
string
diagrams) later became part of loop quantum gravity, and I give the story of
how that happened, along with the more mathematical side of the story
involving
the Jones polynomial, the work of Joyal and Street, etc.

Best,
jb


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