Al-Farabi, Beruni and Ibn Sina on heat phenomena
Abu Nasr al-Farabi (873–950) was born near Otrar (Farab) on the Syr Darya and worked in many fields of science, writing on the structure of matter, heat, motion, sound and optics. In his view a body’s high or low temperature depends on the motion of the particles it consists of — close to the modern molecular-kinetic picture. Ibn Sina (980–1037) explained convection thus: a heated body expands, its density falls and it rises; on cooling its density grows and it sinks. Beruni (973–1048) asked Ibn Sina: if bodies expand with heat and contract with cold, why does a vessel with freezing water crack and why does ice float on water? Ibn Sina answered that bubbles of air are trapped in the ice; Beruni objected, saying he had observed the vessel break outward. This shows that knowledge rests on observation. Beruni and Ibn Sina correctly linked climate change to the slant at which sunlight falls on the Earth. Ibn Sina named the sources of heat as a nearby hot body, motion and friction, and an illuminated body.
“Talk with a scholar”: one pupil plays Beruni, another Ibn Sina and they act out the question-and-answer about freezing water; the class discusses the objection based on observation. Safety: for a freezing experiment use a plastic cup, not glass, fill it only 3/4 and place it in the freezer with an adult.