caustici

Caustici is a term used in multiple disciplines to denote distinct but related concepts, typically grouped under the English term caustics. In chemistry and materials science, caustic substances are highly corrosive and capable of burning organic tissue or causing severe chemical burns. Common examples include sodium hydroxide (caustic soda) and potassium hydroxide (caustic potash). These materials are widely used in cleaning, manufacturing, and various industrial processes, and they require careful handling and protective equipment.

In optics and geometry, caustics refer to the envelopes of light rays reflected or refracted by a curved surface or object. They manifest as bright curves or surfaces, such as the shimmering lines at the bottom of a coffee cup or the patterns seen on the bottom of a swimming pool. The main forms are catacaustics, produced by reflection, and diacaustics, produced by refraction. Caustics can be analyzed with ray tracing and differential geometry, and they give rise to well-known curves such as the cardioid caustic of a circle and the nephroid caustic of certain configurations.

Caustics also appear in mathematics and computer graphics, where they are studied as envelope surfaces and as objects in singularity theory and catastrophes. Their study connects geometric optics, symplectic geometry, and algebraic geometry, illustrating how light rays interact with curved boundaries to produce concentrated intensity along specific curves.

Etymology and usage: the term derives from Latin causticus, from Greek kaustikos, meaning burning. In everyday language, caustic may also describe corrosive substances or figuratively sharp, biting humor.