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Aug 2001

Volume 69, Issue 8, pp. 837-926

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The Thomas rotation

John P. Costella, Bruce H. J. McKellar, Andrew A. Rawlinson, and Gerard J. Stephenson, Jr.

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 837 | Cited 7 times

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We review why the Thomas rotation is a crucial facet of special relativity, that is just as fundamental, and just as “unintuitive” and “paradoxical,” as such traditional effects as length contraction, time dilation, and the ambiguity of simultaneity. We show how this phenomenon can be quite naturally introduced and investigated in the context of a typical introductory course on special relativity, in a way that is appropriate for, and completely accessible to, undergraduate students. We also demonstrate, in a more advanced section aimed at the graduate student studying the Dirac equation and relativistic quantum field theory, that careful consideration of the Thomas rotation will become vital as modern experiments in particle physics continue to move from unpolarized to polarized cross sections. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
03.30.+p Special relativity

Comment on “Nonlocal character of quantum theory,” by Henry P. Stapp [Am. J. Phys. 65 (4), 300–304 (1997)]

Abner Shimony and Howard Stein

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 848 | Cited 10 times

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A 1997 paper by Henry Stapp attempts to achieve a definitive argument for his long-sustained thesis that quantum mechanics implies a nonlocality inconsistent with the locality of relativity theory. His argument assumes both the validity of counterfactual reasoning under certain circumstances and the free choice of performance of experiments, and it specifically refrains from any assumptions about “elements of physical reality” as understood by Einstein, Podolsky, and Rosen. In Sec. I we drastically condense his argument but retain his central principle of inference, called “LOC2,” which he claims is a consequence of relativistic locality. By careful attention to counterfactual reasoning we then throw doubt upon this claim and hence upon his argument as a whole. In Sec. II we answer Stapp’s reply to our critique of the 1997 paper. Section III is a postscript, commenting briefly on Stapp’s answer to Sec. II. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
03.65.Ud Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.)
03.65.Pm Relativistic wave equations
11.10.-z Field theory

Response to “Comment on ‘Nonlocal character of quantum theory,’ ” by Abner Shimony and Howard Stein [Am. J. Phys. 69 (8), 848–853 (2001)]

Henry P. Stapp

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 854 | Cited 3 times

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The question raised by Shimony and Stein is examined and used to explain in more detail a key point of my proof that any theory that conforms to certain general ideas of orthodox relativistic quantum field theory must permit transfers of information over space-like intervals. It is also explained why this result is not a problem for relativistic quantum theory, but, on the contrary, opens the door to a satisfactory realistic relativistic quantum theory based on the ideas of Tomonaga, Schwinger, and von Neumann. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
03.65.Ud Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.)
03.65.Pm Relativistic wave equations
11.10.-z Field theory

Comment on “What quantum mechanics is trying to tell us,” by Ulrich Mohrhoff [Am. J. Phys. 68 (8), 728–745 (2000)]

R. E. Kastner

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 860

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Mohrhoff proposes using the Aharonov–Bergmann–Lebowitz (ABL) rule for time-symmetric “objective” (meaning nonepistemic) probabilities corresponding to the possible outcomes of not-actually-performed measurements between specified pre- and post-selection measurement outcomes. It is emphasized that the ABL rule was formulated on the assumption that such intervening measurements are actually made and that it does not necessarily apply to counterfactual situations. The exact nature of the application of the ABL rule considered by Mohrhoff is made explicit and is shown to fall short of his stated counterfactual claim. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
03.65.Ca Formalism

Objective probabilities, quantum counterfactuals, and the ABL rule—A response to R. E. Kastner

Ulrich Mohrhoff

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 864 | Cited 1 time

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The ABL rule is derived as a tool of standard quantum mechanics. The ontological significance of the existence of objective probabilities is discussed. Objections by Kastner [Am. J. Phys. 69, 860–863 (2001)] and others to counterfactual uses of the ABL rule are refuted. Metaphysical presumptions leading to such views as Kastner is defending in her Comment are examined and shown to be unwarranted. © 2001 American Association of Physics Teachers.
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02.50.Cw Probability theory
03.65.Ta Foundations of quantum mechanics; measurement theory
01.50.-i Educational aids

Carnot cycle for photon gas?

M. Howard Lee

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 874 | Cited 9 times

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The Carnot cycle for a photon gas provides a useful means to illustrate the thermodynamic laws. It is particularly useful in showing the path dependence of thermodynamic functions. Thermodynamic relationships to a neutrino gas are also drawn. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
05.70.Ce Thermodynamic functions and equations of state
05.60.Gg Quantum transport

Poincaré’s 1911–12 proof of quantum discontinuity interpreted as applying to atoms

F. E. Irons

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 879

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As part of a study of Planck’s blackbody radiation theory, H. Poincaré (in 1911–12) advanced a theory which analyzed the partition of energy between “resonators” and the kinetic motion of atoms. Resonators (the objects of Poincaré’s theory) facilitate the exchange of energy between radiation and matter, but otherwise their identity has remained unresolved. Poincaré considered resonators characterized by a particular mean energy ε/[exp(ε/kT)−1], which he showed to necessarily imply quantized energies nε (n=0,1,2,…). We additionally consider resonators characterized by a mean energy ε/[exp(ε/kT)+1], which (using Poincaré’s methodology) we show to necessarily imply quantized energies nε (n=0 and 1). Resonators are here identified with transitions between internal quantum states of atoms. This includes normal electronic atoms characterized by possible energies nε (n=0 and 1), as well as atoms populated by subatomic bosons (such as pions) and characterized by multiple occupancy of quantum states and possible energies nε (n=0,1,2,…). We distinguish between Poincaré’s theory and the closely related analysis by P. Ehrenfest of quantization amongst cavity modes. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
03.65.Ge Solutions of wave equations: bound states
03.65.Sq Semiclassical theories and applications
31.10.+z Theory of electronic structure, electronic transitions, and chemical binding
44.40.+a Thermal radiation
36.10.Gv Mesonic, hyperonic and antiprotonic atoms and molecules

Student understanding of quantum mechanics

Chandralekha Singh

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 885 | Cited 24 times

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We investigate the difficulties of advanced undergraduate students toward the end of a full year upper-level quantum mechanics course with concepts related to quantum measurements and time development. Our analysis is based upon a test administered to 89 students from six universities and interviews with 9 students. Strikingly, most students shared the same difficulties despite variations in background, teaching styles, and textbooks. Concepts related to stationary states, eigenstates, and time dependence of expectation values were found to be particularly difficult. An analysis of written tests and interviews suggests that widespread misconceptions originate from an inability to discriminate between related concepts and a tendency to overgeneralize. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
03.65.-w Quantum mechanics

Measuring and modeling cosmic ray showers with an MBL system: An undergraduate project

David P. Jackson and Matthew T. Welker

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 896 | Cited 2 times

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Following a brief historical introduction, a novel method for inducing and measuring cosmic ray showers using a low-cost microcomputer-based laboratory system is described. This reproduction of Bruno Rossi’s classic experiment uses low counting-rate radiation monitors. The advantage of this is that a simple AND gate can be used to trigger coincidences, which makes the workings of the experiment completely transparent to undergraduate students. The disadvantage is that data must be taken for many days to get reasonably accurate results. A simple theory is presented that models the resulting shower curve quite well. © 2001 American Association of Physics Teachers.
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01.50.Pa Laboratory experiments and apparatus
96.50.sd Extensive air showers
95.55.Vj Neutrino, muon, pion, and other elementary particle detectors; cosmic ray detectors

Materials: An interdisciplinary integrative approach

Robert I. Boughton

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 901 | Cited 2 times

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A full-year survey-of-materials-science course as offered at Bowling Green State University for the past 5 years is described. The course has several unique features, including a modular, team-taught approach with a laboratory component. The laboratory segment is the most demanding portion of the course to set up, and alternatives are discussed in adapting equipment on hand to the course. The feasibility of offering a course in materials science in a nonengineering setting is discussed and some problems associated with offering the course in the “arts and sciences” context are examined. © 2001 American Association of Physics Teachers.
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01.40.Di Course design and evaluation
01.50.-i Educational aids
81.00.00 Materials science

Why bows get stiffer and racquets get softer when the strings are added

Rod Cross

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 907 | Cited 1 time

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The frame of a string instrument is subject to a large tension force when the strings are installed. Intuitively, one might expect that the frame would be stiffened by the strings. Experimental data and a theoretical analysis are presented to show that this is not generally the case. An archer’s bow is much stiffer when it is strung, but a tennis racquet is softened when the strings are added. As a result, the mode frequencies for transverse vibrations increase for a bow and decrease for a racquet when the strings are added. The effect of the strings depends on the extent to which the frame is bent at equilibrium. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
46.25.-y Static elasticity
46.40.-f Vibrations and mechanical waves
01.55.+b General physics

A pulsed jumping ring apparatus for demonstration of Lenz’s law

Paul Tanner, Jeff Loebach, James Cook, and H. D. Hallen

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 911 | Cited 6 times

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Lenz’s law is often demonstrated in classrooms by the use of Elihu Thomson’s jumping ring. However, it is ironic that a thorough analysis of the physics of the ac jumping ring reveals that the operation is due mainly to a phase difference, not Lenz’s law. A complete analysis of the physics behind the ac jumping ring is difficult for the introductory student. We present a design for a pulsed jumping ring which can be fully described by the application of Lenz’s law. Other advantages of this system are that it lends itself to a rigorous analysis of the force balances and energy flow. The simple jumping ring apparatus closely resembles Thomson’s, but is powered by a capacitor bank. The jump heights were measured for several rings as a function of energy stored in the capacitors. A simple model describes the data well. Currents in both the drive coil and ring are measured and that of the drive coil modeled to illuminate some properties of the capacitors. An analysis of the energy flow in the system explains the higher jump heights, to 2 m, when the ring is cooled. © 2001 American Association of Physics Teachers.
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01.50.-i Educational aids
84.32.Tt Capacitors
84.60.Ve Energy storage systems, including capacitor banks
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A simple interference scanner

P. F. Hinrichsen

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 917

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An inexpensive device for measuring interference and diffraction patterns, based on a linear potentiometer for position determination, is described. The linearity, resolution, and reproducibility are discussed. © 2001 American Association of Physics Teachers.
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01.50.Pa Laboratory experiments and apparatus
42.79.Ls Scanners, image intensifiers, and image converters
42.25.Hz Interference
42.25.Fx Diffraction and scattering
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
06.20.F- Units and standards

A simple experiment for measuring the surface tension of soap solutions

F. L. Román, J. Faro, and S. Velasco

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 920 | Cited 7 times

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A simple experimental method for measuring the surface tension of a soap solution is proposed. In the experiment, a soap solution bubble is inflated by a syringe that is also connected to a precision manometer. By measuring the pressure change inside the bubble the surface tension can be calculated using the Young–Laplace equation. Experimental results for both toilet and dishwasher soap solutions are obtained. © 2001 American Association of Physics Teachers.
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01.50.Pa Laboratory experiments and apparatus
68.03.Cd Surface tension and related phenomena
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Comparative Review. The Physics of Oscillations and Waves: With Applications in Electricity and Mechanics

Ingram Bloch, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves

Oscillations and Waves

R. Buckley, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves

Physics of Waves

William C. Elmore, Author, Mark A. Heald, Author, and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves

Vibrations and Waves

A. P. French, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves

The Physics of Waves

Howard Georgi, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves

Vibrations and Waves, 2nd ed.

W. Gough, Author, J. P. G. Richards, Author, R. P. Williams, Author, and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves

Fundamentals of Waves and Oscillations

K. U. Ingard, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves

Oscillations and Waves

Fritz K. Kneubühl, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves

Vibrations and Waves in Physics, 3rd ed.

Iain G. Main, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
43.00.00 Acoustics
46.40.-f Vibrations and mechanical waves

Wave Physics: Oscillations, Solitons, Chaos, 2nd ed.

S. Nettel, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
45.00.00 Classical mechanics of discrete systems
46.40.-f Vibrations and mechanical waves
05.45.-a Nonlinear dynamics and chaos

The Physics of Vibrations and Waves, 5th ed.

H. J. Pain, Author and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
43.00.00 Acoustics
46.40.-f Vibrations and mechanical waves

Principles of Vibration and Sound

Thomas D. Rossing, Author, Neville H. Fletcher, Author, and Lyle Roelofs, Reviewer

American Journal of Physics -- August 2001 -- Volume 69, Issue 8, pp. 922

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Abstract Unavailable
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01.50.-i Educational aids
01.30.Vv Book reviews
41.20.-q Applied classical electromagnetism
43.00.00 Acoustics
46.40.-f Vibrations and mechanical waves
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