Gravitational lens effect revisited through membrane waves
International audience ; By means of experiments and curved manifold simulations, we show that wave propagation past a topological deviation on a two-dimensional flat fabric membrane is analogous to gravitational lensing. Using an ultrafast camera,...
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International audience ; By means of experiments and curved manifold simulations, we show that wave propagation past a topological deviation on a two-dimensional flat fabric membrane is analogous to gravitational lensing. Using an ultrafast camera, we track a membrane plane wave as it crosses a local warped depression. Finite difference simulation, based on the scalar wave equation in a Schwarzschild metric, fully describes the experimental wavefront shape. Comparison between the theoretical and experimental deviation of wave geodesics from straight lines shows that (i) the nonlinear behavior of fabrics due to stretching induces second order effects only and (ii) the experimental depression is closely approximated by the Schwarzschild metric of a gravity well. The experiment demonstrates, in a simple way, how wave propagation is influenced by the topology of the transmission medium.
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