Before the modern understanding of physics, how did scientists view heat? Answer: Early scientists subscribed to the Caloric Theory . They believed heat was an invisible, weightless fluid called "caloric" that flowed from hot objects to cold objects. Context: The worksheet usually asks this to set the stage for why early experiments were conducted. It highlights the shift from "flowing fluid" to the modern kinetic theory (atoms in motion).
At this temperature, all molecular motion ceases. You cannot be "colder" than perfectly still atoms. The Race for Liquefaction nova absolute zero worksheet answers part 1
What is "Joule-Thomson effect"?