  This white paper briefly summarizes the importance of the study of
relativistic cosmic rays, both as a constituent of our Universe, and through
their impact on stellar and galactic evolution. The focus is on what can be
learned over the coming decade through ground-based gamma-ray observations over
the 20 GeV to 300 TeV range. The majority of the material is drawn directly
from "Science with the Cherenkov Telescope Array", which describes the overall
science case for CTA. We request that authors wishing to cite results contained
in this white paper cite the original work.
