caloric theory

Caloric theory was an early scientific idea that thought heat was a kind of invisible, weightless fluid called "caloric" that flowed between objects. It suggested that objects contained a certain amount of this caloric, and this flow explained heating and cooling: heat was gained when caloric moved into an object, and lost when it moved out. Although it helped explain some phenomena, caloric theory was eventually replaced by our modern understanding that heat is energy transfer due to particle movement and vibrations. This shift occurred as scientists better understood the microscopic nature of heat and energy transfer.