Visualizing a Black Hole Event Horizon using a Light-Sensitive Reaction-Diffusion System

We are using chemical reaction-diffusion waves to visualize a black hole event horizon. The event horizon of a black hole is the radius from its center of gravity at which not even light can escape its gravitational pull, but light is able to enter this region. In our table-top analog, we employ the chemical Belousov-Zhabotinsky (BZ) reaction to create easily visible fronts moving in a quasi-two-dimensional system. The black hole is created through a radially symmetrical light gradient with increasing intensity going outward until it reaches a maximal radius, at which the light intensity become zero again – as in the central region. BZ waves created outside our circular light gradient can pass the sharp intensity jump and enter the center regions. BZ waves created at, for example, the center, propagate outward – up the light intensity gradient – but die before reaching the maximal radius. Our experiments are supported by Python simulations using light-sensitive reaction-diffusion waves, replicating our experimental observations.