  We discuss future directions in the development of classical hadrodynamics
for extended nucleons, corresponding to nucleons of finite size interacting
with massive meson fields. This new theory provides a natural covariant
microscopic approach to relativistic nucleus-nucleus collisions that includes
automatically spacetime nonlocality and retardation, nonequilibrium phenomena,
interactions among all nucleons, and particle production. The present version
of our theory includes only the neutral scalar ($\sigma$) and neutral vector
($\omega$) meson fields. In the future, additional isovector pseudoscalar
($\pi^+$,~$\pi^-$,~$\pi^0$), isovector vector ($\rho^+$,~$\rho^-$,~$\rho^0$),
and neutral pseudoscalar ($\eta$) meson fields should be incorporated. Quantum
size effects should be included in the equations of motion by use of the
spreading function of Moniz and Sharp, which generates an effective nucleon
mass density smeared out over a Compton wavelength. However, unlike the
situation in electrodynamics, the Compton wavelength of the nucleon is small
compared to its radius, so that effects due to the intrinsic size of the
nucleon dominate.
