DOCSLIB.ORG

Twentieth Century Physics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Twentieth Century Physics Twentieth Century Physics Play the Physics Nobel match game! A B C D E F G H I J K L M N Wolfgang Pauli Pierre Curie Hideki Yukawa Ray Davis, Jr Maria Goeppert-Mayer Murray Gell-Mann Niels Bohr Werner Heisenberg Albert Einstein Max Planck John Bardeen Otto Stern Marie Curie Paul Dirac Twentieth Century Physics Mark Anthony Reynolds Embry-Riddle University ii Copyright °c 2012 by Mark Anthony Reynolds Second printing, January 2013 Text photographs from nobelprize.org iii For Sarah iv v Acknowledgments I am not a modern physicist by trade, but a plasma physicist, so this book has borrowed heavily from many sources. Its originality consists in packaging a course for sophomore physics majors in a manner di®erent than has been done before. I have used what I believe is the best from the standard modern physics texts, but I have also used unique treatments that I have found in unpublished notes, and journals like the American Journal of Physics. When I have borrowed explanations that are unique, I have cited those sources; however, standard treatments of standard concepts I consider to be in the public domain. I learned modern physics from Matt Sands at U.C. Santa Cruz in 1984 where we used the ¯rst edition of Krane's Modern Physics textbook, which I really liked, especially the historical discussions. Now that I have taught the same class from that text, I still like it, but I feel that it su®ers from the same problems that most modern textbooks su®er from, a too-heavy reliance on the historical approach. I learned quantum mechanics from George Gaspari at U.C. Santa Cruz in 1986-87 and from Ernest Abers at U.C.L.A. in 1987-88. Abers has recently produced a wonderful graduate-level textbook based on his lecture notes,1 and I have used some of that material that is accessible to undergraduates. 1Abers, Quantum Mechanics, 2006. vi vii Preface Tomorrow is going to be wonderful because tonight I do not understand anything. | Niels Bohr Introductory physics is usually taught in historical order. The ¯rst course is me- chanics, which was developed in the 17th century, followed by fluids, thermodynamics and electromagnetism, which were developed in the 18th and 19th centuries. The ¯nal piece of the puzzle, modern physics (or 20th century physics), is left until last, and is also usually presented in a historical manner. It starts with special relativity, and then progresses through \old quantum theory" and basic quantum mechanics. Finally, if there is time in the typical one-semester course, a brief overview of nuclear physics, the standard model of particle physics, and possible some cosmology is presented. This standard procedure illustrates the (now discredited) biological dictum, \ontogeny recapitulates phylogeny."2 However, the brief emphasis placed on particle physics does not give the students a sense of the \big picture" of the standard model, which is our current best guess for how things are put together. While a fundamental understanding of the standard model requires advanced relativity and quantum mechanics, I believe that to be truly a course in \modern physics," we must place this modern understanding in a prominent role. Also, after two or three semesters of physics, students deserve to be shown how all the physics that they have learned ¯ts together, rather than simply viewing the Bohr model, the Schrodinger equation, and special relativity, etc., as simply more in a long list of (separate) topics. For this reason, I start this book with a discussion of the most fundamental particles, quarks and leptons, and then I progress outward to larger, composite, objects: nuclei, and then atoms. This is in reverse historical order, but gives the students a coherent picture of our current knowledge. Of course, some ideas from relativity and quantum mechanics are needed to understand these fundamental particles, so I have placed a basic introduction in Chapter 1, and have also introduced physical concepts as needed. Finally, in the latter part of the book, while covering relativity and quantum theory, I am able to prove some statements that I had previously only quoted. Therefore, the endpoint of our study of relativity and quanta is an explanation of our understanding at the most basic level, i.e., the important applications, rather than simply solving the 1D Schrodinger equation for various potentials, for example, with no apparent motivation. It is true that there is much to be learned studying history, and one of the most important results of a study of physics is to understand precisely how we have come to our conclusions, and why we think they are correct. That is, how do we know what we claim to know? What are the experimental clues that lead us to believe that our current 2An idea from developmental biology which states that the embryonic development of an organism (ontogeny) mirrors the evolutionary development of the species (phylogeny). This theory was ¯rst put forth by Ernst Haeckel (1834-1919). As Haeckel himself wrote in his book Riddle of the Universe at the Close of the Nineteenth Century (1899), \I established the opposite view, that this history of the embryo (ontogeny) must be completed by a second, equally valuable, and closely connected branch of thought - the history of race (phylogeny). Both of these branches of evolutionary science, are, in my opinion, in the closest causal connection; this arises from the reciprocal action of the laws of heredity and adaptation ... `ontogenesis is a brief and rapid recapitulation of phylogenesis, determined by the physiological functions of heredity (generation) and adaptation (maintenance).' " viii model is the best one? And what were the previous models that experiments ruled out?3 Understanding these experimental facts and the logic behind them are as important as understanding the theoretical constructs upon which we base our models. As Robert Millikan [Nobel Prize, Physics, 1923] said, \Science walks forward on two feet, namely theory and experi- ment ... Sometimes it is one foot which is put forward ¯rst, sometimes the other, but continuous progress is only made by the use of both { by theorizing and then testing, or by ¯nding new relations in the process of experimenting and then bringing the theoretical foot up and pushing it on beyond, and so on in unending alternations."4 In fact, a thorough investigation into incorrect models, and the experiments that ¯nally re- vised (or perhaps completely overthrew) those models, is extremely useful. Those stories are not the main thrust of this book, however, and have been relegated either to foot- notes, boxed historical asides, or appendices. Several of the appendices should be studied thoroughly, as they comprise a signi¯cant fraction of the text. The main point, though, is to describe our current thinking about how the world is put together, what it is made of, and how the pieces interact. In telling that story the key historical observations and experiments will be delved into, and pointers to the appropriate appendix will be made for further study. This book is divided approximately into three parts. First, Chapter 1 consists of a brief overview, with statements (not proof) of some of the basic principles of relativity and quantum mechanics that are needed as a foundation. Second, Chapters 2-4 are in- troductions to particle physics, nuclear physics, and atomic physics, which bring you up to speed on the current state-of-the-art. Finally, Chapters 5-7 develop the mathematics that explain the results stated previously: Chapter 5 is a development of special rela- tivity; Chapter 6 is a development of \old" quantum theory, and Chapter 7 derives the full-fledged non-relativistic quantum mechanics. 3Epistemological questions such as these tend to be swept under the rug during a study of classical physics, partially because the answers seem so self-evident among familiar surroundings. When you study physics that is further removed from everyday experience, however, such as subatomic particles, these questions come to the fore, unbidden. A careful consideration of such questions clari¯es the role of classical physics and gives us a deeper understanding of the universe and its inner workings. 4Nobel Lecture, May 23, 1924, The electron and the light-quant from the experimental point of view. ix How to Study There are as many study methods as there are students, but a few principles are universal, and there are a few new ones that apply speci¯cally to modern physics. First, do a lot of outside reading. Unlike in your previous physics courses, which mostly covered classical physics, which is \normal" and \intuitive," in modern physics there will be quite a few new concepts, many of them completely unfamiliar and counter-intuitive, along with lots of new jargon. One way to become familiar with the concepts and comfortable with the language is to expose yourself to as many di®erent viewpoints as possible. Not only should you read this text carefully, but you should read other textbooks and popular accounts. Second, true physical understanding comes through familiarity with the mathematics. So, just as in classical physics, problem solving is crucial to building physical intuition. How best to solve problems? Just as with study habits, there many problem solving methods, but Descartes developed a method 400 years ago that still works. Ren¶eDescartes was one of the ¯rst to discuss the so-called \scienti¯c method." Such a method works as well for solving problems as it does for investigating nature | this is because they are the same activity! Descartes said in Discourse on the Method: A multitude of laws often hampers justice, so that a state is best governed when it has only a few laws which are strictly administered; similarly, instead of the large number of laws which make up logic, I was of the opinion that the four following laws were perfectly su±cient for me, provided I took the ¯rm and unwavering resolution to stick to them clearly at all times.
Load more

Recommended publications
  • Belated Decision in the Hilbert-Einstein Priority Dispute
    (10). As described above, the severely opis- Dinosauria (Univ. of California Press, Berkeley, CA, However, the overall similarity of the pelvis of Archae- 1990). opteryx to those of the enantiornithine birds, espe- thopubic condition of their pelvis is consis- 10. L. Hou, L. D. Martin, Z. Zhou, A. Feduccia, Science cially the presence of the hypopubic cup, as well as tent with the notion that these birds roost- 274, 1164 (1996). the morphology of the London and Berlin Archae- ed in trees. In contrast, based primarily on 11. Q. Ji and S. Ji, Chin. Geol. 10, 30 (1996); see also V. opteryx specimens, offer support for our interpreta- disputed measurements of claw curvature, Morell, Audubon 99, 36 (1997). tion of the pelvic structure of these early birds [L. D. 12. Rather than representing primitive archosaurian Martin, in Origin of the Higher Groups of Tetrapods, Archaeopteryx has been interpreted as structures, it is probable that the hepatic-piston dia- H. P. Schultze and L. Trueb, Eds. (Cornell Univ. adapted primarily for a terrestrial rather phragm systems in crocodilians and theropods are Press, Ithaca, NY, 1991), pp. 485–540. than an arboreal existence (18). However, convergently derived. Pelvic anatomy in early “pro- 18. D. S. Peters and E. Go¨ rgner, in Proceedings of the II todinosaurs” such as Lagosuchus, as well as in all International Symposium of Avian Paleontology, K. as in the enantiornithines, the morphology ornithischian dinosaurs, shows no evidence of the Campbell, Ed. (Los Angeles Museum of Natural His- of Archaeopteryx’s pelvis is best interpreted pubis having served as a site of origin for similar tory Press, Los Angeles, CA, 1992), pp.
    [Show full text]
  • Conference on the History of Quantum Physics Max-Planck-Institut Für Wissenschaftsgeschichte Berlin, 2–6 July 2007 Abstract
    Conference on the history of quantum physics Max-Planck-Institut für Wissenschaftsgeschichte Berlin, 2–6 July 2007 Abstract Title: Walther Nernst, Albert Einstein, Otto Stern, Adriaan Fokker, and the rotational specific heat of hydrogen Author: Clayton A. Gearhart (St. John’s University, Minnesota, USA) In 1911, the German physical chemist Walther Nernst argued that the new quantum theory promised to clear up long-standing puzzles in kinetic theory, particularly in understanding the discrepancies between the predictions of the equipartition theorem and the measured specific heats of gases. Nernst noted that hydrogen gas would be a good test case. The first measurements were published by his assistant Arnold Euken in 1912, and showed a sharp drop in the specific heat at low temperatures, corresponding to rotational degrees of freedom “freezing out.” In his 1911 paper, Nernst also developed a theory for a quantum rotator (a tiny rotating dumbbell representing a diatomic gas). Remarkably, he did not quantize rotational energies. Instead, the specific heat fell off because the gas reached equilibrium by exchanging harmonic oscillator quanta with quantized Planck resonators. Nernst’s theory was flawed. But Einstein adopted a corrected version at the 1911 Solvay Conference, and in 1913, he and Otto Stern published a detailed treatment. Following Nernst, Einstein and Stern did not quantize the rotators. But they did explore the new zero- point energy that Max Planck had introduced in his “second quantum theory” in 1911. Einstein and Stern calculated the specific heat of hydrogen for two cases, one that assumed a zero-point energy for a rotator and one that did not.
    [Show full text]
  • Samuel Goudsmit
    NATIONAL ACADEMY OF SCIENCES SAMUEL ABRAHAM GOUDSMIT 1 9 0 2 — 1 9 7 8 A Biographical Memoir by BENJAMIN BEDERSON Any opinions expressed in this memoir are those of the author and do not necessarily reflect the views of the National Academy of Sciences. Biographical Memoir COPYRIGHT 2008 NATIONAL ACADEMY OF SCIENCES WASHINGTON, D.C. Photograph courtesy Brookhaven National Laboratory. SAMUEL ABRAHAM GOUDSMIT July 11, 1902–December 4, 1978 BY BENJAMIN BEDERSON AM GOUDSMIT LED A CAREER that touched many aspects of S20th-century physics and its impact on society. He started his professional life in Holland during the earliest days of quantum mechanics as a student of Paul Ehrenfest. In 1925 together with his fellow graduate student George Uhlenbeck he postulated that in addition to mass and charge the electron possessed a further intrinsic property, internal angular mo- mentum, that is, spin. This inspiration furnished the missing link that explained the existence of multiple spectroscopic lines in atomic spectra, resulting in the final triumph of the then struggling birth of quantum mechanics. In 1927 he and Uhlenbeck together moved to the United States where they continued their physics careers until death. In a rough way Goudsmit’s career can be divided into several separate parts: first in Holland, strictly as a theorist, where he achieved very early success, and then at the University of Michigan, where he worked in the thriving field of preci- sion spectroscopy, concerning himself with the influence of nuclear magnetism on atomic spectra. In 1944 he became the scientific leader of the Alsos Mission, whose aim was to determine the progress Germans had made in the development of nuclear weapons during World War II.
    [Show full text]
  • The Physical Tourist Physics and New York City
    Phys. perspect. 5 (2003) 87–121 © Birkha¨user Verlag, Basel, 2003 1422–6944/05/010087–35 The Physical Tourist Physics and New York City Benjamin Bederson* I discuss the contributions of physicists who have lived and worked in New York City within the context of the high schools, colleges, universities, and other institutions with which they were and are associated. I close with a walking tour of major sites of interest in Manhattan. Key words: Thomas A. Edison; Nikola Tesla; Michael I. Pupin; Hall of Fame for GreatAmericans;AlbertEinstein;OttoStern;HenryGoldman;J.RobertOppenheimer; Richard P. Feynman; Julian Schwinger; Isidor I. Rabi; Bronx High School of Science; StuyvesantHighSchool;TownsendHarrisHighSchool;NewYorkAcademyofSciences; Andrei Sakharov; Fordham University; Victor F. Hess; Cooper Union; Peter Cooper; City University of New York; City College; Brooklyn College; Melba Phillips; Hunter College; Rosalyn Yalow; Queens College; Lehman College; New York University; Courant Institute of Mathematical Sciences; Samuel F.B. Morse; John W. Draper; Columbia University; Polytechnic University; Manhattan Project; American Museum of Natural History; Rockefeller University; New York Public Library. Introduction When I was approached by the editors of Physics in Perspecti6e to prepare an article on New York City for The Physical Tourist section, I was happy to do so. I have been a New Yorker all my life, except for short-term stays elsewhere on sabbatical leaves and other visits. My professional life developed in New York, and I married and raised my family in New York and its environs. Accordingly, writing such an article seemed a natural thing to do. About halfway through its preparation, however, the attack on the World Trade Center took place.
    [Show full text]
  • Einstein's Life and Legacy
    Reflections Einstein's Life and Legacy Introduction Albert Einstein is the most luminous scientist of the past century, and ranks with Isaac Newton as one among the greatest physicists of all time. There is an enormous amount of material to choose from in talking about Einstein. He is without doubt also the most written about scientist of the past century, may be of all time. The Einstein Archives contain about 43,000 documents, and so far as I know the "Collected Papers of Albert Einstein" have only come upto 1917 with Volume 8 in English translation; another 32 volumes remain to be produced. In the face of all this, this account must be severely selective, and coherent as well. Einstein's life was incredibly rich and intense in the intellectual sense. This will become clear as I go along. In any case let me begin by presenting in Box 1 a brieflisting of a few important dates in his life, howsoever inadequate it may be. He was scientifically active essentially from 1902 upto 1935 at the highest imaginable levels, thus for more than three decades. The Miraculous Year Now let us turn to technical matters. First, a brief mention of his creative outburst of 1905, whose centenary we are celebrating this year. There were four fundamental papers, and the doctoral thesis, all in the six months from March to September. The first paper on the light quantum concept and explanation of the photo electric effect was submitted to Annalen der Physik in March; the second on Brownian Motion in May; and the third setting out the Special Theory of Relativity in June.
    [Show full text]
  • Wolfgang Pauli Niels Bohr Paul Dirac Max Planck Richard Feynman
    Wolfgang Pauli Niels Bohr Paul Dirac Max Planck Richard Feynman Louis de Broglie Norman Ramsey Willis Lamb Otto Stern Werner Heisenberg Walther Gerlach Ernest Rutherford Satyendranath Bose Max Born Erwin Schrödinger Eugene Wigner Arnold Sommerfeld Julian Schwinger David Bohm Enrico Fermi Albert Einstein Where discovery meets practice Center for Integrated Quantum Science and Technology IQ ST in Baden-Württemberg . Introduction “But I do not wish to be forced into abandoning strict These two quotes by Albert Einstein not only express his well­ more securely, develop new types of computer or construct highly causality without having defended it quite differently known aversion to quantum theory, they also come from two quite accurate measuring equipment. than I have so far. The idea that an electron exposed to a different periods of his life. The first is from a letter dated 19 April Thus quantum theory extends beyond the field of physics into other 1924 to Max Born regarding the latter’s statistical interpretation of areas, e.g. mathematics, engineering, chemistry, and even biology. beam freely chooses the moment and direction in which quantum mechanics. The second is from Einstein’s last lecture as Let us look at a few examples which illustrate this. The field of crypt­ it wants to move is unbearable to me. If that is the case, part of a series of classes by the American physicist John Archibald ography uses number theory, which constitutes a subdiscipline of then I would rather be a cobbler or a casino employee Wheeler in 1954 at Princeton. pure mathematics. Producing a quantum computer with new types than a physicist.” The realization that, in the quantum world, objects only exist when of gates on the basis of the superposition principle from quantum they are measured – and this is what is behind the moon/mouse mechanics requires the involvement of engineering.
    [Show full text]
  • I. I. Rabi Papers [Finding Aid]. Library of Congress. [PDF Rendered Tue Apr
    I. I. Rabi Papers A Finding Aid to the Collection in the Library of Congress Manuscript Division, Library of Congress Washington, D.C. 1992 Revised 2010 March Contact information: http://hdl.loc.gov/loc.mss/mss.contact Additional search options available at: http://hdl.loc.gov/loc.mss/eadmss.ms998009 LC Online Catalog record: http://lccn.loc.gov/mm89076467 Prepared by Joseph Sullivan with the assistance of Kathleen A. Kelly and John R. Monagle Collection Summary Title: I. I. Rabi Papers Span Dates: 1899-1989 Bulk Dates: (bulk 1945-1968) ID No.: MSS76467 Creator: Rabi, I. I. (Isador Isaac), 1898- Extent: 41,500 items ; 105 cartons plus 1 oversize plus 4 classified ; 42 linear feet Language: Collection material in English Location: Manuscript Division, Library of Congress, Washington, D.C. Summary: Physicist and educator. The collection documents Rabi's research in physics, particularly in the fields of radar and nuclear energy, leading to the development of lasers, atomic clocks, and magnetic resonance imaging (MRI) and to his 1944 Nobel Prize in physics; his work as a consultant to the atomic bomb project at Los Alamos Scientific Laboratory and as an advisor on science policy to the United States government, the United Nations, and the North Atlantic Treaty Organization during and after World War II; and his studies, research, and professorships in physics chiefly at Columbia University and also at Massachusetts Institute of Technology. Selected Search Terms The following terms have been used to index the description of this collection in the Library's online catalog. They are grouped by name of person or organization, by subject or location, and by occupation and listed alphabetically therein.
    [Show full text]
  • Einstein and Hilbert: the Creation of General Relativity
    EINSTEIN AND HILBERT: THE CREATION OF GENERAL RELATIVITY ∗ Ivan T. Todorov Institut f¨ur Theoretische Physik, Universit¨at G¨ottingen, Friedrich-Hund-Platz 1 D-37077 G¨ottingen, Germany; e-mail: [email protected] and Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences Tsarigradsko Chaussee 72, BG-1784 Sofia, Bulgaria;∗∗e-mail: [email protected] ABSTRACT It took eight years after Einstein announced the basic physical ideas behind the relativistic gravity theory before the proper mathematical formulation of general relativity was mastered. The efforts of the greatest physicist and of the greatest mathematician of the time were involved and reached a breathtaking concentration during the last month of the work. Recent controversy, raised by a much publicized 1997 reading of Hilbert’s proof- sheets of his article of November 1915, is also discussed. arXiv:physics/0504179v1 [physics.hist-ph] 25 Apr 2005 ∗ Expanded version of a Colloquium lecture held at the International Centre for Theoretical Physics, Trieste, 9 December 1992 and (updated) at the International University Bremen, 15 March 2005. ∗∗ Permanent address. Introduction Since the supergravity fashion and especially since the birth of superstrings a new science emerged which may be called “high energy mathematical physics”. One fad changes the other each going further away from accessible experiments and into mathe- matical models, ending up, at best, with the solution of an interesting problem in pure mathematics. The realization of the grand original design seems to be, decades later, nowhere in sight. For quite some time, though, the temptation for mathematical physi- cists (including leading mathematicians) was hard to resist.
    [Show full text]
  • Otto Stern Annalen 4.11.11
    (To be published by Annalen der Physik in December 2011) Otto Stern (1888-1969): The founding father of experimental atomic physics J. Peter Toennies,1 Horst Schmidt-Böcking,2 Bretislav Friedrich,3 Julian C.A. Lower2 1Max-Planck-Institut für Dynamik und Selbstorganisation Bunsenstrasse 10, 37073 Göttingen 2Institut für Kernphysik, Goethe Universität Frankfurt Max-von-Laue-Strasse 1, 60438 Frankfurt 3Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6, 14195 Berlin Keywords History of Science, Atomic Physics, Quantum Physics, Stern- Gerlach experiment, molecular beams, space quantization, magnetic dipole moments of nucleons, diffraction of matter waves, Nobel Prizes, University of Zurich, University of Frankfurt, University of Rostock, University of Hamburg, Carnegie Institute. We review the work and life of Otto Stern who developed the molecular beam technique and with its aid laid the foundations of experimental atomic physics. Among the key results of his research are: the experimental test of the Maxwell-Boltzmann distribution of molecular velocities (1920), experimental demonstration of space quantization of angular momentum (1922), diffraction of matter waves comprised of atoms and molecules by crystals (1931) and the determination of the magnetic dipole moments of the proton and deuteron (1933). 1 Introduction Short lists of the pioneers of quantum mechanics featured in textbooks and historical accounts alike typically include the names of Max Planck, Albert Einstein, Arnold Sommerfeld, Niels Bohr, Max von Laue, Werner Heisenberg, Erwin Schrödinger, Paul Dirac, Max Born, and Wolfgang Pauli on the theory side, and of Wilhelm Conrad Röntgen, Ernest Rutherford, Arthur Compton, and James Franck on the experimental side. However, the records in the Archive of the Nobel Foundation as well as scientific correspondence, oral-history accounts and scientometric evidence suggest that at least one more name should be added to the list: that of the “experimenting theorist” Otto Stern.
    [Show full text]
  • Theory and Experiment in the Quantum-Relativity Revolution
    Theory and Experiment in the Quantum-Relativity Revolution expanded version of lecture presented at American Physical Society meeting, 2/14/10 (Abraham Pais History of Physics Prize for 2009) by Stephen G. Brush* Abstract Does new scientific knowledge come from theory (whose predictions are confirmed by experiment) or from experiment (whose results are explained by theory)? Either can happen, depending on whether theory is ahead of experiment or experiment is ahead of theory at a particular time. In the first case, new theoretical hypotheses are made and their predictions are tested by experiments. But even when the predictions are successful, we can’t be sure that some other hypothesis might not have produced the same prediction. In the second case, as in a detective story, there are already enough facts, but several theories have failed to explain them. When a new hypothesis plausibly explains all of the facts, it may be quickly accepted before any further experiments are done. In the quantum-relativity revolution there are examples of both situations. Because of the two-stage development of both relativity (“special,” then “general”) and quantum theory (“old,” then “quantum mechanics”) in the period 1905-1930, we can make a double comparison of acceptance by prediction and by explanation. A curious anti- symmetry is revealed and discussed. _____________ *Distinguished University Professor (Emeritus) of the History of Science, University of Maryland. Home address: 108 Meadowlark Terrace, Glen Mills, PA 19342. Comments welcome. 1 “Science walks forward on two feet, namely theory and experiment. ... Sometimes it is only one foot which is put forward first, sometimes the other, but continuous progress is only made by the use of both – by theorizing and then testing, or by finding new relations in the process of experimenting and then bringing the theoretical foot up and pushing it on beyond, and so on in unending alterations.” Robert A.
    [Show full text]
  • The Value of Vague Ideas in the Development of the Periodic System of Chemical Elements
    The Value of Vague Ideas in the Development of the Periodic System of Chemical Elements. Thomas Vogt Departments of Chemistry & Biochemistry and Philosophy University of South Carolina Abstract The exploration of chemical periodicity over the past 250 years led to the development of the Periodic System of Elements and demonstrates the value of vague ideas that ignored early scientific anomalies and instead allowed for extended periods of normal science where new methodologies and concepts are developed. The basic chemical element provides this exploration with direction and explanation and has shown to be a central and historically adaptable concept for a theory of matter far from the reductionist frontier. This is explored in the histories of Prout’s hypothesis, Döbereiner Triads, element inversions necessary when ordering chemical elements by atomic weights, and van den Broeck’s ad-hoc proposal to switch to nuclear charges instead. The development of more accurate methods to determine atomic weights, Rayleigh and Ramsey’s gas separation and analytical techniques, Moseley’s x-ray spectroscopy to identify chemical elements, and more recent accelerator-based cold fusion methods to create new elements at the end of the Periodic Table point to the importance of methodological development complementing conceptual advances. I propose to frame the crossover from physics to chemistry not as a loss of accuracy and precision but as an increased application of vague concepts such as similarity which permit classification. This approach provides epistemic flexibility to adapt to scientific anomalies and the continued growth of chemical compound space and rejects the Procrustean philosophy of reductionist physics. Furthermore, it establishes chemistry with its explanatory and operational autonomy epitomized by the periodic system of elements as a gateway to other experimental sciences.
    [Show full text]
  • Ginling College, the University of Michigan and the Barbour Scholarship
    Ginling College, the University of Michigan and the Barbour Scholarship Rosalinda Xiong United World College of Southeast Asia Singapore, 528704 Abstract Ginling College (“Ginling”) was the first institution of higher learning in China to grant bachelor’s degrees to women. Located in Nanking (now Nanjing) and founded in 1915 by western missionaries, Ginling had already graduated nearly 1,000 women when it merged with the University of Nanking in 1951 to become National Ginling University. The University of Michigan (“Michigan”) has had a long history of exchange with Ginling. During Ginling’s first 36 years of operation, Michigan graduates and faculty taught Chinese women at Ginling, and Ginlingers furthered their studies at Michigan through the Barbour Scholarship. This paper highlights the connection between Ginling and Michigan by profiling some of the significant people and events that shaped this unique relationship. It begins by introducing six Michigan graduates and faculty who taught at Ginling. Next we look at the 21 Ginlingers who studied at Michigan through the Barbour Scholarship (including 8 Barbour Scholars from Ginling who were awarded doctorate degrees), and their status after returning to China. Finally, we consider the lives of prominent Chinese women scholars from Ginling who changed China, such as Dr. Wu Yi-fang, a member of Ginling’s first graduating class and, later, its second president; and Miss Wu Ching-yi, who witnessed the brutality of the Rape of Nanking and later worked with Miss Minnie Vautrin to help refugees in Ginling Refugee Camp. Between 2015 and 2017, Ginling College celebrates the centennial anniversary of its founding; and the University of Michigan marks both its bicentennial and the hundredth anniversary of the Barbour Gift, the source of the Barbour Scholarship.
    [Show full text]