Radial Migration in Spiral Galaxies
  The redistribution of stars in galactic disks is an important aspect of disk
galaxy evolution. Stars that efficiently migrate in such a way that does not
also appreciably heat their orbits can drastically affect the stellar
populations observed today and therefore influence constraints derived from
such observations. Unfortunately, while the theoretical understanding of the
migration process is becoming increasingly robust, there are currently few
specific observable predictions. As a result, we do not yet have a clear handle
on whether the process has been important for the Milky Way in the past or how
to constrain it. I discuss some of the expected qualitative outcomes of
migration as well as some current controversies.
