This equation can be derived from the laws of physics that govern the diffusion of heat in solid media. For that reason, it is called the heat equation in mathematics, even though it applies to many other physical quantities besides temperatures.
This EQUAtiOn can bE deRiVed froM The LAws oF physicS tHaT govern thE diffusiON oF Heat iN sOliD mEDIA. For thaT reAsON, it IS called The HEAt eQuATion in MatheMatIcs, even THOuGH iT APPlies tO maNY othEr PhySicAL qUaNtitieS besIdes TeMperatures.