tailieunhanh - The Coming of Materials Science Episode 5

Tham khảo tài liệu 'the coming of materials science episode 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 140 The Coming of Materials Science profound investigation in 1877 of the probabilistic basis of entropy culminating in the relation s k log w where .S is entropy and w is the probability of a microstate this immortal equation is carved on Boltzmann s tomb. It is Boltzmann s work which has really made possible the modern flowering of statistical thermodynamics of solids. The sequence of events is traced with historical precision in a new biography of Boltzmann Cercignani 1998 . An entire chapter 7 is devoted to the Gibbs Boltzmann connection culminating in a section entitled Why is statistical mechanics usually attributed to Gibbs and not to Boltzmann . Cercignani attributes this to the unfamiliarity of many physicists early in this century with Boltzmann s papers partly because of the obscurity of his German style but Gibbs is not easy to read either and partly because the great opinion-formers of early 20th-century physics Bohr and Einstein knew little of Boltzmann s work and were inclined to decry it. The circumstances exemplify how difficult it can be to allocate credit appropriately in the history of science. Magnetism The study of the multifarious magnetic properties of solids followed in due course by the sophisticated control of those properties has for a century been a central concern both of physicists and of materials scientists. The history of magnetism illustrates several features of modern materials science. That precocious Cambridge engineer Alfred Ewing whom we have already met as the adviser of the young Walter Rosenhain was probably the first to reflect seriously Ewing 1890 about the origin of ferromagnetism . the characteristics of strong permanent magnets. He recognised the possibility that the individual magnetic moments presumed to be associated with each constituent atom in a solid somehow kept each other aligned and he undertook a series of experiments with a lattice of magnetised needles that demonstrated that such an interaction .