Page-curve-like entropy dynamics in a classical elastic bit lattice

Classical nonlinear lattices can be engineered to reproduce information-theoretic phenomena usually reserved for quantum systems. Here, we show that four elastically coupled steel spheres—configured as two epoxy-bonded dumbbells—reproduce the characteristic rise-and-fall “Page curve” of bipartite entanglement entropy. Each dumbbell forms an elastic bit, classical analogous to a qubit, whose normal modes act as the classical counterpart of a qubit's basis states. By exciting the lattice with harmonic driving, recording the granules’ velocities with a laser-Doppler vibrometer, and monitoring its time-resolved normal-mode amplitudes, we map the system's state into a four-dimensional Hilbert space and define a classical entanglement entropy from the reduced modal density matrix. This entropy rises and falls cyclically, tracing a profile that mirrors the Page curve predicted for unitary black-hole evaporation at the level of bipartite entropy evolution, while remaining as a classical analog of subsystem correlation dynamics rather than a model of Hawking radiation or quantum gravity. The observed dynamics arise entirely from nonlinear mode coupling and are tunable through the driver frequency, amplitude, and phase. Our results extend entanglement-based diagnostics into tabletop mechanics, demonstrating that carefully designed classical platforms can emulate key features of quantum information flow and offering a new, accessible avenue for probing foundational questions at the intersection of dynamics and information theory.