Absolute Zero is 0K

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A Damn Interesting read for those of you with some time to kill:

Absolute Zero is 0K
Written by Allen Bellows, DamnInteresting.com

Near the heart of Scotland lies a large morass known as Dullatur Bog. Water seeps from these moistened acres and coalesces into the headwaters of a river which meanders through the countryside for nearly 22 miles until its terminus in Glasgow. In the late 19th century this river adorned the landscape just outside of the laboratory of Sir William Thompson, renowned scientist and president of the Royal Society. The river must have made an impression on Thompson--when Queen Victoria granted him the title of Baron in 1892, he opted to adopt the river’s name as his own. Sir William Thompson was thenceforth known as Lord Kelvin.

Kelvin's contributions to science were vast, but he is perhaps best known today for the temperature scale that bears his name. It is so named in honor of his discovery of the coldest possible temperature in our universe. Thompson had played a major role in developing the Laws of Thermodynamics, and in 1848 he used them to extrapolate that the coldest temperature any matter can become, regardless of the substance, is -273.15°C (-459.67°F). We now know this boundary as zero Kelvin.

Once this absolute zero temperature was decisively identified, prominent Victorian scientists commenced multiple independent efforts to build machines to explore this physical frontier. Their equipment was primitive, and the trappings were treacherous, but they pressed on nonetheless, dangers be damned. There was science to be done.

Prior to this 19th-century cold rush, most European scientists believed that coldness itself was an actual physical substance--made up of atoms of an airborne primordial gas. This explained why water expanded upon freezing--it was taking in a large amount of these cold particles. Physicist Robert Boyle dispelled this notion in 1665 by painstakingly weighing water before and after putting it outdoors on a freezing night, demonstrating that only its volume had changed, not its mass. This helped naturalists to start hypothesizing in the right direction, but in 1783, renowned French chemist Antoine de Lavoisier undid most of this progress by popularizing his own theory that heat is an invisible, weightless, self-repellent vapor called caloric, and that coldness is merely a depletion of the same. This "dark heat" theory was also wrong, but it modeled observations so well that it remained dominant for almost a century.

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?

The rest of the article is after the link, for those of you whom this is of interest to. There's a pretty good audio reading available there, if you'd prefer to listen to it while you work.