摘要:

Editor’sNote: The substance of this article was delivered at the dedication of the Schenectady Archives of Science and Technology, Schaffer Library, Union College, in Schenectady, New York, in 1976. It presents, for both students and teachers of physics, a picture of the kind of atmosphere in which discoveries are really made and the sophistication with which one must search the archives in order to reconstruct this atmosphere. The original version was published by arrangement with the Friends of the Union College Library, and copies of it may be obtained, on request, from the Schaffer Library, Union College, Schenectady, NY 12308.

ISSN:0002-9505    

DOI:10.1119/1.11049

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

A novel method of teaching advanced physics laboratories has been developed. The method simulates research conditions by creating a student‐written literature and requiring students to make researchlike decisions.

ISSN:0002-9505    

DOI:10.1119/1.11050

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The optics, mechanics, and mathematics workshops for ’’The Age of Newton’’ are described in detail. These workshops can be used separately and are of particular interest to an institution developing a curriculum in the history of science, or a new approach to the education of nonscience students, as they involve extensive laboratory experience as well as the customary readings. Although the core of the material covered is Newtonian, use is made of appropriate modern concepts and equipment.

ISSN:0002-9505    

DOI:10.1119/1.11051

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The purpose of this article is to outline a nonrigorous and highly intuitive introductory approach to the sort of group representation theory used in molecular and solid state physics. We examine the real three‐space spanned by orthonormal polar basis vectors {‖i〉, i=1,2,3}; first it is shown that the familiar block diagonal ’’rotation matrix’’ is simply the {‖i〉} representation of the geometric transformation operator ?φwhich causes a counterclockwise rotation of any three‐space polar vector by the angle φ about the ‖3〉 axis. By applying this argument to thegroupof symmetry operators of the ammonia molecule, it becomes self‐evident that the two irreducible representations obtainable from the {‖i〉} representation ofC3vcorrespond to subspaces of real‐space invariant relative to the six operators of that group. And the basis vectors which span these invariant subspaces (and which produce the corresponding irreducible representations) have clearly defined symmetry (A1andE) properties under the operations ofC3v. This idea is further illustrated in consideration of the representation produced by the in‐plane normal modes of vibration of the three hydrogen atoms in ammonia. Finally, it is shown that the approach can readily be extended into function space.

ISSN:0002-9505    

DOI:10.1119/1.11052

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

This continuation of the English rendition of Einstein’s 1907 essay on relativity, of which the first part appeared in the June 1977 issue of this Journal, is devote to Parts II‐IV of the essay, dealing with the relativistic treatments of electrodynamics, optics, mechanics, and thermodynamics. The original text of these parts covers 27 printed pages. However, owing to the nature of the subject matter and the character of the original exposition, it was possible to reproduce here the essential content of the original text intact in terms of a free rendition, using modern notation, and retaining all the original formulas with their numbering, and also including direct translations of all passages of possible historical interest. Mathematical amplifications of a few of the key derivations in the original text are presented in added footnotes.

ISSN:0002-9505    

DOI:10.1119/1.11053

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

From letters, personal reminiscences, and the published works of the authors involved, we describe the historical development of the Bhabha system of first‐order relativistic wave equations for arbitrary spin. The simplest special cases of these equations reduce to the Dirac and DKP (Duffin–Kemmer–Petiau) equations for spin‐1/2 and spins 0 and 1, respectively.

ISSN:0002-9505    

DOI:10.1119/1.11054

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The notion of self‐adjointness as distinct from Hermiticity is usually avoided in elementary quantum mechanics courses due to a feeling that it has nothing to do with physics or else is too mathematical. This is definitely not the case, and we use the model of a free particle restricted to motion on a line over a finite interval, to demonstrate this. For such a particle, there is one‐parameter infinity of self‐adjoint extensions of the momentum operator. We use one of these, corresponding to ’’antiperiodic’’ boundary conditions, to show that physical phenomena different from the usual case (periodic boundary conditions) occur. In fact, in this case, we have a model displaying many of the properties of spontaneously broken symmetry.

ISSN:0002-9505    

DOI:10.1119/1.11055

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The classical scattering equation for a charged particle moving in a plane perpendicular to the axis of inverse first‐ (cylindrical), second‐ (spherical), and third‐power central fields has been solved by a general computer program for the experimental case of a bounded field. The particle enters with a known energy and impact parameter through a hole in a grounded electrode having a large but finite radius, and exits at the same radius after passing by a very small central electrode having a given potential. Results were computed and plots are given for the distances of closest approach of the particle to the scattering center, and the exit angles for the three cases for a large range of impact parameters and ratios of applied potential to initial energy. Our computer results for the spherical field check analytic solutions for Rutherford α particle scattering.

ISSN:0002-9505    

DOI:10.1119/1.11056

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

We consider the general relativity field equations in two‐ and three‐dimensional space–times. We find that in a two‐dimensional space–time we can have curvature but not matter. In a three‐dimensional space–time we find that empty space must be flat, that a de Sitter solution exists, and that finite mass distributions with constant surface density must have zero ’’surface tension.’’ Finally, an expanding dust‐filled universe turns out to be like Milne’s model.

ISSN:0002-9505    

DOI:10.1119/1.11057

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

Quasiclassical quantization of a spherical pendulum in which the moving point mass and the center have electric and magnetic charge, respectively, is discussed. It is shown that for this system quantum conditions do not simply select between classical orbits. The requirement of spherical symmetry leads to the quantization condition of Dirac for the product of the charges and the total angular momentum may be either an integer or a half‐integer multiple of h/.

ISSN:0002-9505    

DOI:10.1119/1.11058

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP