New Developments in Spiral Structure Theory

Progress in the theory of spiral structure has stalled for many years largely because no observational data existed that could discriminate between the various mechanisms proposed to account for the phenomenon. This situation changed dramatically with the publication of the Geneva-Copenhagen Survey, which provides full phase-space information for a large, and unbiased, sample of nearby F & G stars. I will present an extensive review of the current state of spiral structure theory before showing how data from the GCS impinge on the generating mechanism for spirals.