  The collision of two clouds of Fermi gas at unitarity (UFG) has been recently
observed to lead to shock waves whose regularization mechanism, dissipative or
dispersive, is being debated. While classical, dissipative shocks, as in gas
dynamics, develop a steep, localized shock front that translates at a
well-defined speed, dispersively regularized shocks are distinguished by an
expanding region of short wavelength oscillations with two speeds, those of the
leading and trailing edges. For typical UFG experimental conditions, the
theoretical oscillation length scale is smaller than the resolution of present
imaging systems so it is unclear how to determine the shock type from its
structure alone. Two experimental methods to determine the appropriate
regularization mechanism are proposed: measurement of the shock speed and
observation of a one-dimensional collision experiment with sufficiently tight
radial confinement.
