HistoryNEWSLETTER Physics A FORUM OF THE AMERICAN PHYSICALof SOCIETY • VOLUME XI • NO. 2 • WINTER 2011 The Laser: Its History and Impact on Precision Measurements (joint session with the FIAP) at the 2010 “April” meeting, Washington D.C. By Daniel Kleppner, Forum Chair At the “April” 2010 meeting (held in February to be joint with the American Association of Physics Teachers),the FHP and the Forum on Industrial and Applied Physics sponsored “The Laser: Its History and Impact on Precision Measurement” (Ses- sion X4). The speakers were Joseph Giordmaine, Frederico Capas- so, and John Hall. Dr. Giordmaine, completed his Ph.D. with Charles Townes at Columbia University, on the use of the maser amplifier in planetary astronomy. Later at Bell Labs he worked with ruby lasers, harmonic generation, and nonlinear optics, and is now retired vice president of physical science research at NEC Labs. Dr. Capasso pioneered band structure engineering through molecular beam epitaxy, resulting in electronic and photonic devices dominated by mesoscopic scale quantum effects, includ- ing the quantum cascade laser. Dr. Hall, currently a NIST Senior Fellow Emeritus and Fellow at the Joint Institute for Laboratory Astrophysics (JILA), won the 2005 Nobel Prize in physics (with Theodor W. Hnsh) for his work on laser-based precision spectros- copy and the optical comb technique. oseph Giordmaine traced the pioneering advances made in the laser during the years 1960-1964, in his Jtalk “The Laser: Historical Perspectives and Impact on Precision Measurements.” The seminal concept, stimu- Fig. 1. Charles Townes (left) and J. P. Gordon standing with the lated emission, introduced by Albert Einstein in 1917, took second ammonia beam maser at Columbia University, 1955. AIP nearly forty years to bear fruit. In the mid 1920s, media Emilio Segre Visual Archives, Physics Today Collection. with an inverted population had been considered by Hendrik A. Kramers, John H. Van Vleck, and Richard C. Tolman, and in the 1930s Hans Kopfermann and Ernst A. Lautenberg saw effects of population inversion on disper- In This Issue sion. Valentin A. Fabrikant in 1939 searched for negative absorption (viz., amplification, excessive stimulated radia- 2011 Pais Prize Winner 2 tion compared to absorbed radiation). Willis Lamb and Ernest Rutherford, Edward M. Purcell, and Joseph Weber all considered implications of negative absorption. How- Editor’s Corner 3 ever, nobody visualized applications for negative absorp- tion and the matter was not pursued. Upcoming FHP Sessions 4 The crucial idea, using an inverted population to sus- tain oscillations, was conceived by Charles H. Townes (Fig. 1). In a famous incident while he was sitting alone early on March Meeting Reports 6 a bench in Franklin Park, Washington, Townes suddenly realized that if excited atoms were surrounded by a cavity, New Books of Note 14 Continues on page 2 News of the Forum: 2011 Abraham Pais Prize for History of Physics Citation: “For his sophisticated, techni- extensively on Charles Darwin and cally masterful historical studies of the 19th century evolutionary theories, emergence of quantum field theory and and since the mid 1980s on the history quantum electrodynamics, and broadly of physics during the 20thcentury. He insightful biographical writing on several is the author of QED and the Men of the most influential physicists of the Who Made It, Bethe and Oppen- 20th century: Einstein, Oppenheimer, and heimer and the Moral Responsibil- Bethe.” ity of Scientists, and of Einstein and Oppenheimer: The Meaning of Genius. ilvan (Sam) Schweber was He has just finished Volume 1 of Faith born in Strasbourg, France in in Reason, a biography of Hans Bethe. S1928. He came to the United He helped establish the Dibner Insti- States in July 1942. He attended the tute for the History of Science and City College of NY and graduated as Technology at MIT in 1988 and was a chemistry and physics major in 1947. its first director. In 2005 he retired He thereafter obtained a MS in Phys- from Brandeis University as the Koret ics from the University of Pennsylva- Professor of the History of Ideas and Silvan Schweber nia in 1949 and a PhD from Princeton Professor of Physics, emeritus. Since Brandeis University, Emeritus University in 1952 working with Pro- 1981 he has been a Faculty Associate fessor Arthur Wightman. From 1952 in the Department of the History of to 1954 he was an NSF post doctoral Science at Harvard. He is a fellow of fellow at Cornell University. In 1955 the APS, the American Association he accepted a faculty appointment at for the Advancement of Science and Brandeis University. of the American Academy of Arts and Dr. Schweber is the author with Sciences. Hans Bethe and Fred de Hoff- Dr. Schweber will present the 2011 The Forum on History of Phys- man of Volume I of Mesons and Pais Prize Lecture, entitled “Shelter ics of the American Physical Fields (1955) and of an Introduc- Island 1947 Revisited,” in the “Solvay Society publishes this Newsletter tion to Relativistic Quantum at 100” session of the April meeting semiannually. Nonmembers who Field Theory (1961). In the mid- (Anaheim, CA, April 30). We congratu- wish to receive the Newsletter 1970s his research interests shifted to late Dr. Schweber as the recipient of should make a donation to the the history of science. He has written the 2011 Pais Prize. ■ Forum of $5 per year (+ $3 addi- tional for airmail). Each 3-year volume consists of six issues. Laser History The articles in this issue repre- sent the views of their authors Continued from cover and are not necessarily those of the Forum or APS. the radiated energy could build up a After extended success with ammonia Editor field that would sustain the emission. masers at various laboratories, a ruby His molecular oscillator consisted of maser was constructed at Columbia. Dwight E. Neuenschwander nothing more than a state-selected In 1964 Arno A. Penzias and Robert W. Department of Physics beam of molecules passing through a Wilson used a ruby maser amplifier Southern Nazarene University microwave resonator. In 1954, maser in their discovery of the cosmic back- Bethany, OK 73008 oscillation was demonstrated in his ground radiation. [email protected] group by Jim Gordon and Herb Zei- During the summer of 1957 (405) 491-6361 ger (the term “maser” was coined that Townes started working with Arthur year by Townes). Shortly after, Niko- Schawlow at Bell Labs on the theory Associate Editor lay Basov and Alexander Prokhorov and details of an optical maser. That Don Lemons demonstrated maser operation at the September he had Giordmaine, then a Department of Physics Lebedev Institute. In the summer of graduate student, witness a notebook Bethel College 1956, Nicolaas Bloembergen intro- entry laying out the general principles. North Newton, KS 67117 duced the concept of a 3-level solid Their proposal, using a potassium [email protected] state maser, opening the way to the creation of practical maser amplifiers. Continues on page 5 2 Volume XI, No. 2 • Winter 2011 • History of Physics Newsletter Editors’ Corner The philosopher of scence Imre Lakatos happened, we know how easy it is, with treatment by strict and unchangeable rules.”[4] argued that revisionist accounts of sci- our advantage of hindsight, to introduce Students of science are “brainwashed” ence were acceptable, provided they were special relativity or quantum mechanics in different ways at different ages. Around supplemented with footnotes to preserve by describing how they could have been the time of middle school, they are brain- historical facts. In an imagined dialogue neatly cut from whole cloth in their present washed though a checklist “Scientific between Lakatos andPaul Feyerabend, their forms, made to appear complete and whole Method” that presents science as catechism, editor had Lakatos uttering these lines: in a kind of spontaneous creation. with rigid rules to be memorized for a quiz. “…I might agree that methods in science Of course, arranging a network of A few years later in university physics (and mathematics) change and can be expected physics concepts into a pattern of logi- courses it is oh-so-easy to brainwash them to change. The important thing is to try and cal coherence is necessary for genuine again with smooth “rational reconstruc- ensure that such methodological changes are for understanding. Thus on the first day of tions” of science history. the better. However, we can take charge of this electrodynamics class we are justified While a personal logical reconstruction only if we succeed in rationally reconstruct- in asserting that “Electrostatics consists in each learner’s mind forms a creative task ing change in standards as we reconstruct essentially of Coulomb’s law along with whose completion is essential to content change in scientific theories. From this point the superposition principle.” In so saying mastery, teaching only such pre-edited of view my ‘Changing Logic’ [a book Lakatos we are emphasizing the discipline’s logical reconstructions creates an impression of planned but never finished] aims at grasping structure. But although the mastery of a how science is done that is as misleading the ‘unfolding of reason’ and presenting it ‘cut paradigm’s logic is essential, to stop there as the sixth-grade checklist. (One wonders and dry,’ after its process of formation has been deprives the appreciator of a richer expe- if such experiences were the stimuli that led completed. rience. Every physics concept, like every the logical positivists astray, with their rigid “…And my exhortation towards a rational person, object, or community, has a story. rules about how science was supposed to reconstruction of individual historical cases In the adventure of seeking knowledge, if be done). should be taken as a historicographical pro- we nail the paradigm’s logic but neglect its A contribution to my own education gramme, an encouragement towards defining story, how deeply can we claim to know that has come with my role as editor of the reasons and strategies which have produced it? Samuel Crothers illustrated the point in this newsletter, is seeing first-hand the pas- new ideas.