  The magnetic flux noise induced by vortices in thin superconducting films is
studied. Rigid vortices in thin films as well as pancake vortices in the
pancake gas regime are addressed. The vortex dynamics is described by a Feynman
path integral which fully accounts for the balance between vortex entropy and
vortex energetics. We find that vortex pair creation (annihilation) in the
presence of pinning is a natural source for noise with a 1/f spectrum.
