  For over four decades, synchrotron-radiating sources have played a series of
pathfinding roles in the study of galaxy clusters and large scale structure.
Such sources are uniquely sensitive to the turbulence and shock structures of
large-scale environments, and their cosmic rays and magnetic fields often play
important dynamic and thermodynamic roles. They provide essential complements
to studies at other wavebands. Over the next decade, they will fill essential
gaps in both cluster astrophysics and the cosmological growth of structure in
the universe, especially where the signatures of shocks and turbulence, or even
the underlying thermal plasma itself, are otherwise undetectable.
Simultaneously, synchrotron studies offer a unique tool for exploring the
fundamental question of the origins of cosmic magnetic fields. This work will
be based on the new generation of m/cm-wave radio telescopes now in
construction, as well as major advances in the sophistication of 3-D MHD
simulations.
