Cold

by Bill Streever

  It is February eighth and just below freezing in London. Fat, wet snowflakes fall lazily along the train tracks. Passengers are soaked from the knees down, dark trousers and skirt hems sticking to skinny legs, but the train is well heated. School has been canceled, and kids play in the open spaces between rows of small brick homes. There are few sleds but many snowballs. In a soccer field, a boy defends a pathetic snow fort, its walls melting around him, more slush than snow. Where he has harvested snow for the walls, a moat of still-green grass surrounds the fort. The boy is inexplicably shirtless, with shadows of his ribs showing on pale English skin.

  The trains are running even later than usual. “I couldn’t even get me car up the drive,” a woman tells me.

  Later, I walk through patches of sidewalk slush from Waterloo station to Westminster Abbey. Here, on a summer day in 1620, cold was an issue of some importance. This was two centuries before Frederic Tudor’s ice trade and Thomas Moore’s fur-lined icebox and Jacob Perkins’s refrigerator. King James I — fifty-four years old, barrel-chested but somewhat bent over with rickets, a child of the Little Ice Age — did not do well in the heat. He overdressed, in part because he was a slave to fashion but in part to repel the knives of would-be assassins. Beneath his royal clothes, he tended to sweat. His skin itched. It is said that he became overheated when exposed to the sun.

  When gray-bearded Cornelis Drebbel told King James that he could cool the interior of Westminster Abbey, the king listened. Drebbel, a Dutchman, was part scientist, part alchemist, part showman, part con man. He bragged of being able to change his appearance from one second to the next, of summoning ghosts, and of having created a perpetual motion machine. In Holland, he was known as the pochans or grote ezel, the braggart or big donkey, and he had been imprisoned in Prague for a combination of bad politics and bad debt. Now he lived through the largesse of King James. In exchange, on this day he would cool the interior of Westminster Abbey, the length of a football field with ten stories of open space between ceiling and floor.

  The summer heat would have warmed the abbey’s stone blocks. Even during the day, candles and perhaps lanterns would have burned inside, lighting the shadows and further heating the interior. This would not be an easy space to cool. But even an incremental cooling would impress an audience unaccustomed to air-conditioning. And although the room was tall, its air was still, and Drebbel would have known that the cold air — his cold air — would tend to stay low, near the floor.

  There would be those who would see a change in the temperature as an act of magic, of sorcery, a summoning of winter in the middle of summer. Drebbel would do little to discourage such impressions. This was a time when cold was believed to come from a single source, called a primum frigidum. Aristotle himself believed that the primum frigidum was simply water, and in Drebbel’s time Aristotle and the other ancient thinkers were still considered authoritative. Drebbel worked a hundred years before Fahrenheit and forty-five years before Robert Boyle’s extensive work on cold, heat, and pressure. This was a time when controlled experiments and open communication about those experiments were not expected, when curiosity was by no means a virtue, when Francis Bacon was still formulating and promoting what would come to be called the scientific method. Neither the scientists nor their audiences were interested in sharing knowledge. The interest was in entertaining and being entertained, in amazing and being amazed.

  Flash forward nearly four centuries. A verger shows a group of tourists around the abbey. I tag along asking questions. The verger is olive-skinned, wearing a black robe, his voice musical and his words and sentences made by combining clearly clipped syllables. He uses the word “chaps” in reference to long-dead royalty and even saints. He waves a flag to guide us through the abbey. He tells us that his title, verger, comes from the Latin for staff or rod. A verge is used by the verger to prod common worshippers away, allowing free passage for God’s more important servants, for royalty and clergy and other favored mortals. He is animated, like a nervous little bird trying to stay warm, surrounded by the acid-worn stone figures of kings and queens and writers and artists and scientists. He shows us the verge that he uses, a brass baton, more symbolic than effective, the character of the stick perhaps reflecting the character of the man’s position.

  King James, no longer in need of air-conditioning, lies buried under the floor, the spot marked by a memorial tile. Laurence Olivier’s ashes reside here, too. Chaucer, or the body of someone believed to have been Chaucer, rests here, along with Dickens. Shakespeare did not want to be buried here but is honored by a stone figure. Close to Shakespeare’s memorial, a wall tile mentions Mary Shelley. There is a tile, too, for Lord Kelvin, whose temperature scale went to absolute zero. And here is one for Faraday, a man who showed that melting ice absorbed heat — that the change from solid to liquid, and by extension from liquid to gas, absorbed heat in a way that could not be explained by the temperature change alone. Mix a pound of boiling water with a pound of water just above the freezing point, and you get two pounds of water at about 120 degrees. But mix a pound of boiling water with a pound of ice, and you get two pounds of water at something like 50 degrees. The change in state from ice to water — the breaking up of the molecular rows and columns that give ice its structure — accounts for seventy degrees of temperature change.

  Viewed from above, Westminster Abbey has the shape of a cross. Drebbel likely emptied his bag of tricks in and around the Abbey’s sacrarium, near the top of the cross. The walls and ceilings at that time would have been stained with soot and candle grease. Against these walls, Drebbel would have laid out casks or troughs. He had access to snow and ice stored in pits beneath nearby estates. He could find reasonably cool water just outside, in the Thames. And, importantly, he had potassium nitrate, also called saltpeter or niter. Drebbel knew, possibly from work first published in 1558 by Giambattista della Porta under the title Natural Magick, that mixing snow with niter resulted in sudden cooling. He was too secretive to leave written records, but Francis Bacon, who was not present that day in 1620, heard of the events. Bacon wrote that in “the late experiment of artificial freezing, salt is discovered to have great powers of condensing,” and that “nitre (or rather its spirit) is very cold, and hence nitre or salt when added to snow or ice intensifies the cold of the latter, the nitre by adding to its own cold, but the salt by supplying activity to the cold of the snow.” In short, niter mixed with ice yields an endothermic reaction. More commonly experienced exothermic reactions — such as the burning of wood or coal or gunpowder — generate heat, but endothermic reactions — such as the mixing of niter and ice — absorb heat.

  King James and his entourage would have marched into the abbey, their gowns damp with sweat. They would have chilled quickly. Drebbel very probably added certain theatrical effects. The royal personage was entertained. His entourage was entertained. Some in the king’s company may have feared this unseasonable cold. The king, who himself had once authored a book on witchcraft titled Daemonologie, likely exchanged clever comments with those standing nearby. And then they left.

  The verger has never heard of Drebbel. Westminster Abbey remains today without air-conditioning. “It gets quite hot in the summer,” the verger tells me. “Quite hot indeed. The stone walls themselves get hot, you see, so it doesn’t cool off much in the evening.” Outside, the sun hangs low in the overcast sky. Here in the city, most of the snow is gone, but the sidewalks remain slushy. London is dreary and cold, King James I is long dead, and the Dutchman Cornelis Drebbel is all but forgotten.

  Seventeen years before Daniel Fahrenheit came up with his temperature scale, at a time when neither molecular motion nor the atomic notion of matter were well understood, Guillaume Amontons reasoned that cold must bottom out. His reasoning was based on thoughts about changes in pressure and volume, then known to be affected by temperature. As it grew colder, pressure and volume decreased. Taken far enough, pressure and volume would have to reach into negative values, but neg
ative pressure and negative volume made no sense, so temperature, he believed, must have a bottom limit, an absolute zero. His thoughts made others realize that they lived in a very warm world, a world that hovered around the freezing point of water but that could be much colder. William Thomson, who would be knighted and known to posterity as Lord Kelvin, developed the Kelvin scale in 1848. The Kelvin scale used the same increments promoted by Anders Celsius, but it started with zero as the coldest possible temperature and put the freezing of water at a balmy 273 K.

  Two centuries after Drebbel, before Kelvin developed his scale, scientists were reaching for this zero, turning their creative and intellectual talents toward what became at times an ugly competition for extreme cold. They took risks. They used chemicals that could burn one’s skin and worked at temperatures that would crack both glass and metal. Things exploded. It was not uncommon for scientists to task their assistants with the hands-on work of the more dangerous experiments. Michael Faraday was the first to liquefy chlorine gas, in 1823, at a temperature of 130 degrees below zero. That same year, in the course of a single month, he was on the receiving end of three laboratory explosions, each of them causing minor eye injuries. Charles Saint-Ange Thilorier, the first to freeze carbon dioxide into dry ice, ran an experiment that resulted in an assistant losing both legs. In 1886, James Dewar’s laboratory went up. Dewar himself, who had invented the vacuum bottle that was originally used in the laboratory and only later adapted for drinks, was nearly killed.

  The scientists did not share the commercial interests of the Ice King, Frederic Tudor. Instead, they saw themselves engaged in a search for “the cold pole” and as surveyors working on “the map of Frigor.” They saw their quest as equivalent to those of geographical explorers, of Columbus and Magellan and Cook, and of their contemporaries, the polar explorers Franklin and Greely and Scott. Medieval mapmakers had once labeled unknown lands in the far north “ultima Thule,” and the scientists adopted the phrase. Heike Kamerlingh Onnes, who would liquefy helium in 1908, wrote, “The arctic regions in physics incite the experimenter as the extreme north and south incite the discoverer.” He was right in this assessment.

  Like the Arctic explorers, the scientists were men obsessed. They often invested their own wealth. They gave up opportunities for personal financial gain in exchange for opportunities to explore the frontiers of Frigor. They seemed to worry more about an experiment failing than about the safety risk posed by laboratory explosions and fires. Onnes, in a letter to Dewar, was concerned that “the bursting of the vacuum glasses during the experiment would not only be a most unpleasant incident, but might at the same time annihilate the work of many months.” They had bitter rivalries, arguing over who reached the record low temperatures first, who was first to liquefy this gas or that gas. Frustrated when he realized that Onnes had won the race to liquefy helium, Dewar dressed down a senior assistant, blaming him for delays. The assistant vowed that he would never set foot in the Royal Institution as long as Dewar lived and then held true to his word.

  These men, these explorers of Frigor, worked brutally long hours, conducting single experiments that could run from before dawn to late into the night, with laboratory assistants scurrying about, checking gauges, turning wheels that in turn spun threaded bars that in turn compressed gases. They opened valves, and — when things went well, when nothing broke or jammed or exploded — they transferred fluids such as liquid nitrogen, liquid oxygen, and liquid hydrogen from one vessel to another.

  They were not above theatrics. In 1899, celebrating the hundredth anniversary of the Royal Institution, Dewar lectured to an audience of dignitaries and scientists. The men wore frock coats, and the women wore formal dresses. Dewar played with liquid oxygen. The men and women watched thermometers scream downward. Dewar liquefied oxygen before their eyes, turning a clear gas into a blue liquid. He showed them how electrical resistance decreased as metals were cooled. There were lots of tricks to be played near ultima Thule. Mercuric oxide went from scarlet to light orange. Rubber, ivory, feathers, and sponges phosphoresced with their own bluish glow.

  The scientists expected even stranger phenomena as temperatures dropped further. Dewar himself, speaking of absolute zero, said that “molecular motion would probably cease, and what might be called the death of matter would ensue.”

  But absolute zero was unattainable. Reaching absolute zero can be likened to reaching the speed of light: as one approaches light speed, acceleration becomes increasingly difficult, and as one approaches absolute zero, further cooling becomes increasingly difficult. A simpleminded and not altogether wrong explanation: at very low temperatures, any attempt to remove more heat generates heat. But science is closer to absolute zero than to the speed of light. Science is within billionths of a degree of absolute zero, within spitting distance of ultima Thule. Things have become increasingly difficult and increasingly frustrating, and the death of matter, in a sense, has ensued.

  If one ignores Drebbel’s stunt at Westminster Abbey, the race toward absolute zero started in earnest in 1748, when the Scottish medical professor William Cullen used a vacuum pump to suck down the pressure of one vessel, cooling it sufficiently to freeze the water in a surrounding, outer vessel. He published the work in a Scottish journal under the title “Of the Cold Produced by Evaporating Fluids and of Some Other Means of Producing Cold,” but he took it no further. Almost a hundred years later, cascading was developed, in which vaporization of one liquid cools another gas sufficiently to create a second liquid, which is in turn vaporized to cool another gas into a liquid state, and so forth and so on. Another trick involved the expansion of gas through a valve, allowing gas molecules to spread out without performing work and therefore to cool, taking advantage of what physicists know as the Joule-Thomson effect. At this point, still well above absolute zero, the men exploring toward ultima Thule were working at dangerously low temperatures, in a realm that left metal brittle and instantly froze flesh.

  Helium was an important prize. In July 1908, starting before dawn, Heike Kamerlingh Onnes cascaded chloromethane to liquefy ethylene, liquid ethylene to liquefy oxygen, liquid oxygen to liquefy air, and liquid air to liquefy hydrogen. It had taken him seven years to prepare for the experiment. At seven o’clock in the evening, thirteen hours after the experiment began, Onnes became the first human being to see liquid helium. “It was a wonderful moment,” he later recalled. Helium goes from gas to liquid at 452 degrees below zero Fahrenheit, less than seven degrees above absolute zero.

  Below the temperature of liquid helium, cascading and the Joule-Thomson effect are of little value. Things become increasingly peculiar. For Onnes and his colleagues, trained in classical physics, the properties of matter no longer made sense. Even calling liquid helium a liquid is not quite right. It is more of a superfluid, a phase of matter that behaves something like a liquid but that has almost no viscosity.

  Albert Einstein weighed in. Working with the Indian physicist Satyendra Nath Bose, Einstein realized that quantum physics was at play. In the quantum world, atomic motion occurs in incremental steps: it is as though you can travel at one mile per hour, five miles per hour, or ten miles per hour, but not at three miles per hour or four and a half miles per hour or seven and a quarter miles per hour. Bose and Einstein realized that at extremely low temperatures, the wave functions that described individual atoms would overlap. The wave functions would then merge, and groups of atoms would behave as one. In 1924, Bose and Einstein proposed that a new state of matter would exist at extremely low temperatures. This state of matter — not gas, not liquid, not solid — became known as the Bose-Einstein condensate.

  It took sixty years to develop the technology to knock off those last couple of degrees on the road to the Bose-Einstein condensate. By then, both Bose and Einstein were dead. In the quest for ultima Thule, new tricks had been discovered. When light hits an object and is absorbed, the object is warmed, but when light hits an object and is reflected, it is cooled. With lasers,
pure wavelengths can be generated and reflected off a packet of atoms. In 1995, Eric Cornell and Carl Wieman used lasers to cool a packet of rubidium atoms to ten-thousandths of a degree above absolute zero, to the point at which molecular motion almost stops. “It’s like running in a hail storm so that no matter what direction you run the hail is always hitting you in the face,” Wieman said. “So you stop.” It was still too hot for a Bose-Einstein condensate. To cool their rubidium atoms further, they used what in principle is the same trick used by their nineteenth-century forebears — a form of evaporative cooling, allowing the most energetic atoms to escape and leaving only the less energetic and cooler atoms behind. “It’s the exact same physics as how a cup of coffee cools,” Wieman explained during a 2001 press conference. “The steam coming off is the most energetic coffee atoms. The ones left behind get colder.” In the end, the rubidium had cooled to something like fifty-billionths of a degree above absolute zero, or just shy of 460 degrees below zero Fahrenheit. And the atoms were no longer a gas or a liquid or a solid. In a brand of alchemy that would have made the likes of Cornelis Drebbel cackle in glee, the kind of matter known to men such as Dewar and Onnes and Boyle had died, and what was left was a Bose-Einstein condensate — a thick glob of about two thousand atoms condensed into a single super atom surrounded by warmer atoms, reportedly looking something like the pit inside a translucent cherry made of a glowing cloud of very cold rubidium.