At the dawn of the Industrial Revolution, newfangled steam machines began to chuff heat into work, and science into profits. Cracking the true nature of heat would lead to more efficient power plants, so the utmost intellectual and financial assets converged upon the problem. When centuries of “common sense” were finally set aside in favor of the scientific method, theorists and experimenters gradually ascertained that all molecules in nature are restless, agitated things that randomly wiggle and wobble, bumping into neighbors like billiard balls on an overcrowded table. The net effect of these molecular motions is what we observe as heat, and temperature is directly proportional to the speed of these movements. From this, Lord Kelvin inferred that if one were to reduce the heat in a substance sufficiently, one would reach a temperature where the molecules become entirely still--a minimum possible temperature. His calculations correctly indicated -273.15°C as this physical boundary.
This landmark discovery invited even more inquiry than it had quieted. Might it be possible to actually reach absolute zero? What would happen to molecules forced into such stillness? Would they disintegrate? Would they convert to a yet-to-be-observed phase of matter? Who goes there? What is the meaning of this?