Elastic Mimicry of Gravitational Waves

We design a new mechanical metamaterial for a series of experiments to mimic the characteristics of gravitational waves. In a multi-layer lattice consisting of bars, sliders, and elastic springs, we observe tensor-polarized elastic waves, where the stable and harmonic propagation of the strain tensor resembles the spacetime metric tensor perturbed by gravitational waves. Experimental results show that this simple design is a fertile platform to realize the rich physics of novel elastic strain waves with spin-2 rotational symmetry. The phase difference between the "+" polarization and "x" polarization of the gravitational wave is simulated by controlling two coordinated components in our design. The frequency and amplitude of the gravitational wave are simulated by the slider motion. Our demonstrations may potentially lead to unprecedented capabilities to bridge the field of mechanical metamaterials to studies in general relativity and cosmology.