After surveying of the role of symmetry in quantum field theory, I review
how symmetry breaks during phase transitions, when fields relax to a ground
state less symmetric than the physical laws governing them. I show how
topological properties of the symmetry groups --- both gauged and global
--- classify nontrivial configurations that inevitably form in these phase
transitions. Such configurations (called solitons) have notorious consequences,
from enhancing superconductivity to motivating the inflationary universe.
I conclude with consequences investigated in my own work: introduction
of charge-violating interactions by ``Alice'' strings, both gauged and
global, due to Aharonov-Bohm scattering.
Katherine Benson, an assistant professor at Emory University, did her
undergraduate degree in physics at Duke University. She then went to Harvard
to do doctoral work with Sidney Coleman, specializing in quantum field
theory. After graduating in 1991, she completed postdocs at the Institute
for Advanced Study in Princeton, and at UCSD, before visiting Emory in
fall of 1995, and joining Emory's regular faculty this fall.