(n.) The doctrine or science of light, explaining its nature and phenomena; optics.

Newtonian physics acoustics actinology actinometry aerophysics applied physics astrophysics basic conductor physics biophysics catoptrics chemical physics cryogenics crystallography cytophysics dioptrics electron optics electron physics electronics electrophysics geometrical optics geophysics heliography heliology heliometry infrared spectroscopy macrophysics mathematical physics mechanics medicophysics microphysics microscopics microscopy natural philosophy natural science nuclear physics optical physics optometry philosophy photics photography photology photometry physic physical chemistry physical optics physical science physicochemistry physicomathematics physics psychophysics radiation physics radionics solar physics solid-state physics spectrometry spectrophotometry spectroscopy statics stereophysics stereoscopy telescopy theoretical physics thermodynamics zoophysics