If you are interested, please send your questions to Borzu or me, or add them to the comments area. We will ask Borzu for another Q&A session in the near future.
And the book suggested by Mohammad: "Fast Light, Slow Light and Left-Handed Light" by P W Milonni, 2005. [Amazon, PDF] In comments use dollar signs and latex to get math formating. For instance $\frac{7}{3}=\det\begin{bmatrix}a&b\\ c&d\end{bmatrix}$.
On the brighter note, here are books that some of our participants might find interesting and that Springer kindly allows you to download as a part of covid-19 "relieve":
The text Christian Rose mentioned (and currently reads) can be downloaded here. (It contains a nice chapter on math of lattices.)
See also the lectures recorded at Oxford. Thanks, Christian.
The lectures on Knot Theory started. Here are recordings of the first four: