  The nuclear pasta -- a novel state of matter having nucleons arranged in a
variety of complex shapes -- is expected to be found in the crust of neutron
stars and in core-collapse supernovae at subnuclear densities of about
$10^{14}$ g/cm$^3$. Due to frustration, a phenomenon that emerges from the
competition between short-range nuclear attraction and long-range Coulomb
repulsion, the nuclear pasta displays a preponderance of unique low-energy
excitations. These excitations could have a strong impact on many transport
properties, such as neutrino propagation through stellar environments. The
excitation spectrum of the nuclear pasta is computed via a molecular-dynamics
simulation involving up to 100,000 nucleons. The dynamic response of the pasta
displays a classical plasma oscillation in the 1-2 MeV region. In addition,
substantial strength is found at low energies. Yet this low-energy strength is
missing from a simple ion model containing a single-representative heavy
nucleus. The low-energy strength observed in the dynamic response of the pasta
is likely to be a density wave involving the internal degrees of freedom of the
clusters.
