  These are the third 50 issues of This Week's Finds of Mathematical Physics,
from April 9, 1997 to June 18, 2000. These issues discuss quantum gravity,
topological quantum field theory, n-categories and other topics in mathematics
and physics. They also contain a series of expository mini-articles on homotopy
theory. They were typeset in 2020 by Tim Hosgood. If you see typos or other
problems please report them. (I already know the cover page looks weird; you
can get a better-looking version at https://math.ucr.edu/home/baez/twf_latex/)
