Random packing in three dimensions

Abstract

Unraveling the complexities of random packing in three dimensions has long puzzled physicists. While both experiments and simulations consistently show a maximum density of 64 percent for tightly packed random spheres, we still lack an unambiguous and universally accepted definition of random packing. This paper introduces an innovative standpoint, depicting random packing as spheres closest to a quenched Poisson field of random points. We furnish an efficacious algorithm to probe this proposed model numerically. We unearth a unique out-of-equilibrium thermodynamic phenomenon, akin to a `latent heat', that emerges at $\phi_J \approx 0.65$ in three dimensions. This phenomenon is accompanied by global and local structural rearrangements, marking a jamming transition from an unjammed state to a jammed one. Notably, such a `jamming' transition is absent for two-dimensional random packing. Our innovative approach paves a new avenue for defining random packing and provides novel insights into the behavior of amorphous materials.