  We demonstrate that there is only one physical process required to explain
the spectrum and the variability of the radio source at the dynamical center of
our Galaxy, Sgr A*, in the frequency range from $\approx$1 to $\approx$1000
GHz, namely optically thin synchrotron radiation that is emitted from a
population of relativistic electrons. We attribute the observed variability to
variable energy input from an accretion disk around Sgr A* into the
acceleration of the electrons.
