The Density Gap Between Supernova Core Bounce and the Neutron-Branch Density Bound

In a core-collapse supernova the infalling iron core halts at nuclear density, rebounds, and launches the shock whose revival remains the central problem of supernova theory. Because the halt is called a bounce, it invites confusion with the turnaround that a spin-torsion density bound would produce. This paper separates the two events numerically. Bounce densities of 2e17 to 5e17 kg per cubic metre lie a factor of about 3.2e+40 below the neutron-branch bound of 9.72e+54 g per cubic centimetre. The free-fall time at bounce density, 1.213e-04 seconds, contrasts with 6.739e-25 seconds at the bound, and adiabatic compression from bounce to the bound would require a temperature near 3.19e+24 K rather than the 1e11 K of a real core. The supernova bounce is a nuclear event, entirely distinct from the density bound. Simulated from stated assumptions, not measured.