  We show that the excellent optical and gamma-ray data available for GRB
080319B rule out the internal shock model for the prompt emission. The data
instead point to a model in which the observed radiation was produced close to
the deceleration radius ($\sim10^{17}$ cm) by a turbulent source with random
Lorentz factors $\sim10$ in the comoving frame. The optical radiation was
produced by synchrotron emission from relativistic electrons, and the
gamma-rays by inverse Compton scattering of the synchrotron photons. The
gamma-ray emission originated both in eddies and in an inter-eddy medium,
whereas the optical radiation was mostly from the latter. Therefore, the
gamma-ray emission was highly variable whereas the optical was much less
variable. The model explains all the observed features in the prompt optical
and gamma-ray data of GRB 080319B. We are unable to determine with confidence
whether the energy of the explosion was carried outward primarily by particles
(kinetic energy) or magnetic fields. Consequently, we cannot tell whether the
turbulent medium was located in the reverse shock (we can rule out the forward
shock) or in a Poynting-dominated jet.
