👉 In physics, a caustic is a type of surface that appears in certain types of optical phenomena. These are regions where light refracts or diffuses differently between two media, such as air and water. When light enters these caustics, it bends or reflects off the surfaces at different angles, causing an interference pattern to appear. This phenomenon is often observed when a beam of light strikes a surface that has a sharp edge or an irregular shape, like a crack in a glass bottle.
