Absolute Zero and the Conquest of Cold (37 page)
Read Absolute Zero and the Conquest of Cold Online
Authors: Tom Shachtman
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* Another hundred years would elapse before French physicist and chemist Joseph-Louis Gay-Lussac would definitively refine this notion into the law that at constant pressure, all gases have the same coefficient of expansion.
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* Evans inspired two other attempts at refrigeration. He corresponded with the English inventor Richard Trevithick, who in 1828 also proposed a refrigerating machine based on Evans's work, a machine that was never built; and he exchanged letters with Jacob Perkins, an American expatriate in London, who patented an Evans-type device in 1834 and for a while made ice from a barge that floated on the Thames. Unable to generate much enthusiasm for his product, Perkins failed commercially; as events would later show, the venture was about thirty years ahead of its time.
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*Gorrie also recommended draining the swamps to remove the local cause of malaria, even before the principal transmitter of the disease, the swamp-born mosquito, had been identified as its carrier.
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* Carnot's rejection of caloric in his post-1824 notes was one reason why the Académie des Sciences was eager to publish them in 1878, even though it had ignored Carnot during his lifetime. The second reason was that the notes showed clearly that a Frenchman had preceded all the German and English scientists in coming to understandings of both the first and second laws of thermodynamics.
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*The explanation for this eluded the generation of Seebeck and Peltier and was approached later by Kelvin. See chapter 6,
[>]
.
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*By "imponderable," Mayer meant weightless.
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* The figure for absolute zero was eventually refined toâ273.15°C.
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* Also made forcefully by Helmholtz in 1847.
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* Their initial idea was to test a hypothesis put forth by Mayer, with which both Joule and Thomson disagreed. By this time, Mayer had gained some respect as a theorist, and, after having spent the previous five years doing nothing more mentally strenuous than cultivating his garden in Heilbronn, he had recovered his sanity; he also had won a new champion in Great Britain, John Tyndall of the Royal Institute, who began to tout the insights of Mayer and to belittle the contributions of Joule. Tyndall disliked Joule for having caught and exposed an important error in one of Tyndall's papers, which embarrassed the flamboyant Tyndall. Eventually, this contretemps would provoke a battle over who had been the first to announce the conservation of energy, a battle in which Thomson came galloping to the defense of Joule, to the latter's great satisfaction.
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*It would develop no heat because nothing would resist its passageâresistance is what produces heat in electrically conductive wires, in, for example, the coils of a conventional electric toaster when they are activated. And if there was no heat, no energy would be dissipated.
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* True to his word, Lennox returned to the Royal Institution after Dewar's death in 1923.
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*Liquid helium had to be transferred from the vessel in which it had been collected at the end of the liquefaction process, by means of a specially constructed siphonâcooled and isolated from the environmentâand held in another vessel, one large enough to also contain measuring apparatus for whatever experiment was being conducted and a stirrer to ensure uniformity of temperature in the liquid helium.
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*The theory also had portions that made reference to the vibration of molecular particles; more about this aspect later in the chapter.
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* In the same issue of
Nature
as Kapitsa's first letter about the flow of helium
II
was a similar and equally revelatory letter on the same subject by John Allen and his Cambridge graduate student Donald Misener.
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*The Fermi surface is not a real surface but a geometric description of the behavior of conducting electrons in a solid. A "surface" of constant energy, it separates energy states filled with certain kinds of electrons from those that are unfilled. At absolute zero, those particles with a certain spin would fill all the available energy levels up to the Fermi surface, but none above that. The absence of these particles is a characteristic of a substance in the superconducting state; in contrast, a substance in a normal conducting state has plenty of electrons of several kinds, which are the basis of normal resistivity.
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*A similar notion occurred independently and simultaneously to physicist Herbert Frölich while on a sabbatical year at Purdue University. Frölich's theory also predicted the isotope effect before it was discovered.
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*Perhaps the most important of these was the 1995 discovery of the "top quark." Decades earlier theorists had predicted six different kinds of quarks. Five "flavors" had been found and identified in the 1970s: the pairs up and down, strangeness and charm, and the single one called bottom. Thus the last to be discovered was the other half of the third pair, called the top quark.
