Simulation of the general-relativistic light deflection with a plastic lens

One of the most important predictions of the general theory of relativity is the light deflection by gravitating masses. This effect was verified for the first time in 1919 with light rays passing close by our Sun. It is now one of the most important tools for discovering dark matter. Here we explain how the general-relativistic light deflection can be simulated with an appropriately shaped plastic lens and we demonstrate this with a lens made from plexiglass. In this way an important aspect of general relativity can be visualised in a way that makes it accessible to high school students.