LOW-TEMPERATURE PHENOMENA

the behaviour of matter at temperatures closer to absolute zero (-273.15 C [-459.67 F]) than to room temperature. At such temperatures the thermal, electric, and magnetic properties of many substances undergo great change, and, indeed, the behaviour of matter may seem strange when compared with that at room temperature. Superconductivity and superfluidity can be cited as two such phenomena that occur below certain critical temperatures; in the former, many chemical elements, compounds, and alloys show no resistance whatsoever to the flow of electricity, and, in the latter, liquid helium can flow through tiny holes impervious to any other liquid. Additional reading F.E. Simon et al., Low Temperature Physics: Four Lectures (1952, reprinted 1961); and K. Mendelssohn, The Quest for Absolute Zero: The Meaning of Low Temperature Physics, 2nd ed. (1977), are excellent nontechnical summaries. Another account is found in Anthony Leggett, Low Temperature Physics, Superconductivity, and Superfluidity, ch. 9 in Paul Davies (ed.), The New Physics (1989), pp. 268288. The Journal of Low Temperature Physics (semiannual) contains useful articles. Also informative are Progress in Low Temperature Physics (irregular), theoretical and experimental research reports and review articles, all with extensive bibliographies; K. Mendelssohn (ed.), Progress in Cryogenics, 4 vol. (195964), which complements the previous work, with more emphasis on applied problems and developments; Fritz London, Superfluids, vol. 1, Macroscopic Theory of Superconductivity, 2nd ed. (1961), and vol. 2, Macroscopic Theory of Superfluid Helium (1954, reprinted 1964), the classic presentation of theory; H.M. Rosenberg, Low Temperature Solid State Physics: Some Selected Topics (1963), fairly elementary; Marshall Sittig, Cryogenics: Research and Applications (1963); two articles from the American Journal of Physics, both by D.M. Ginsberg, Resource Letter Scy-1 on Superconductivity, 32:8589 (1964), and Resource Letter Scy-2 on Superconductivity, 38:949955 (1970), introductory reviews with descriptive bibliographies; P.G. de Gennes, Superconductivity of Metals and Alloys, trans. from French (1966, reprinted 1989), a presentation of the foundations and applications of the theory; Charles G. Kuper, An Introduction to the Theory of Superconductivity (1968); William E. Keller, Helium-3 and Helium-4 (1969), advanced-level summaries of theory; R.D. Parks (ed.), Superconductivity, 2 vol. (1969); W.D. Gregory, W.N. Matthews, Jr., and E.A. Edelsack (eds.), The Science and Technology of Superconductivity, 2 vol. (1973); Michael Tinkham, Introduction to Superconductivity (1975, reprinted 1980), an intermediate introduction; A.C. Roseinnes and E.H. Rhoderick, Introduction to Superconductivity, 2nd ed. (1978), basic, with an emphasis on application; Guy K. White, Experimental Techniques in Low-Temperature Physics, 3rd ed. (1979, reissued 1987), a detailed discussion; David R. Tilley and John Tilley, Superfluidity and Superconductivity, 3rd ed. (1990); and Dieter Vollhardt and Peter Wlfle, The Superfluid Phases of Helium 3 (1990).Authoritative review articles of higher-temperature superconductors can be found in D.M. Ginsberg (ed.), Physical Properties of High Temperature Superconductors, 3 vol. (198992). Other reports include those by M.K. Wu et al., Superconductivity at 93 K in a New Mixed-Phase Y-Ba-Cu-O Compound System at Ambient Pressure, Physical Review Letters, 58(9):908910 (March 2, 1987); Anil Khurana, Superconductivity Seen Above the Boiling Point of Nitrogen, Physics Today, 40(4):1723 (April 1987); K. Alex Mller and J. Georg Bednorz, The Discovery of a Class of High-Temperature Superconductors, Science, 237(4819):113339 (Sept. 4, 1987); and Stuart A. Wolf and Vladimir Z. Kresin, Novel Superconductivity (1987). Anthony James Leggett Donald M. Ginsberg