摘要:

The oversimplification of issues in the history of science leads to a misunderstanding of the nature of scientific progress. For instance, most texts and many histories of science have perpetuated the myth that the distinction between Newton's theory of light and that of Huygens was clear cut and simple. They have compounded their error by indicating that Foucault's experiment in 1850, where he found the speed of light to be slower in water than in air, was “crucial” evidence in favor of Huygens's theory, thereby “disproving” the corpuscular theory of Newton. The position is defended that the theories of Newton and Huygens did not represent simple opposites; Newton's theories on light have been frequently misrepresented; and Foucault's experiment was not a crucial one.

ISSN:0002-9505    

DOI:10.1119/1.1973004

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

A critical analysis is made of Descartes's ideas concerning the nature of light and its refraction in order to ascertain the logic of his conclusion that light travels with a greater velocity in water than in air. The conclusions are (1) that Descartes was not an adherent of an emission theory but conceived of light as a pressure in a transparent medium, (2) that he believed this pressure was transmitted from the light source at an incredibly rapid but nevertheless finite velocity, and (3) that he was led to his erroneous conclusion concerning the velocity of light in rare and dense media by confusing the pressure and the velocity of the light propagation in the explanation of his experimental results.

ISSN:0002-9505    

DOI:10.1119/1.1973005

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

Whaples's highly abstract proof that the zeroth law of thermodynamics leads to the existence of empirical temperature functions is paraphrased so as to make it more accessible to physicists. An understanding of Whaples's work is all the more important if one recognizes that it may be the only correct proof.

ISSN:0002-9505    

DOI:10.1119/1.1973006

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

A new method of introducing nonholonomic constraints into the Lagrangian formulation of mechanics is presented and compared with the conventional approach. An example is given using the new formulation. The example falls outside the scope of the conventional approach, but is easily solvable by the new method. Several generalizations of the new method outside the domain of Newtonian mechanics are mentioned.

ISSN:0002-9505    

DOI:10.1119/1.1973007

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

Data in the 1962 National Register of Scientific and Technical Personnel reveal that 42% of all physicists in the United States are employed outside the academic community and do not have Ph.D.'s. When the characteristics and needs of industrial research laboratories are examined against a backdrop of typical physics curricula, serious deviations between the two are discernible. When it is further realized that 46% of all U. S. physicists are working in the classical fields of electronics, electromagnetism, optics, acoustics, fluids, and mechanics, further doubts about course emphasis arise. It is proposed that an academic option be introduced which emphasizes classical physics at an advanced level, while providing a general grasp of the quantum and statistical base. A continuous and unified laboratory program is also recommended. Modifications would extend through the master's degree. The result could be a curriculum capable of efficiently producing the applied physicists which industry clearly needs.

ISSN:0002-9505    

DOI:10.1119/1.1973008

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

In order to illustrate some of the basic principles of statistical mechanics, a study is made of the nonequilibrium behavior of a one-dimensional particle confined to a finite box with perfectly reflecting walls. The statistical aspects of the analysis are due to the incompleteness of the initial information. Liouville's equation is solved exactly and completely, and it is shown that this finite, isolated, reversible system exhibits irreversible statistical behavior. By applying information theory to the results obtained, it is shown that the irreversibility exhibited by this system consists in the information becoming less relevant to the experiments which can be performed on the system.

ISSN:0002-9505    

DOI:10.1119/1.1973009

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

This paper describes a family of oval curves first studied by Maxwell and which may be called generalized ellipses. Their equation may be written as follows:aS + bS′ = K, whereaandbare certain integral values,Kany value constant, andSandS′the distances of a current point from the two foci. The simplest oval results froma = 1,b = 2. Other values ofaandbgenerate similar ovals which are described. If in certain of these ovals the inside and outside regions are filled with material of a definite refractive index, then light proceeding from one focus to the other, will refract stigmatically at the oval surface.

ISSN:0002-9505    

DOI:10.1119/1.1973010

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

If a meter bar of lengthland of rectangular cross-section is to be compared with a line standard of typicallyHcross-section, then it is necessary to support the rectangular bar in such a way that the distance between the engravings will not be altered by deflections due to the weight of the bar. This is achieved by supporting the bar on two half-circular cylinders located at the Airy Points which are, actually, two parallel, symmetrically spaced lines separated by the distancel/3. This problem is both interesting in itself and suitable for use in an undergraduate course in mechanics. It is presented here for its pedagogical value since it is apparently unknown to most professors of physics of the present generation.

ISSN:0002-9505    

DOI:10.1119/1.1973011

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

A basic time asymmetry is said to exist in the conventional quantum theory of measurement because the initial state, determined by the initial measurement, suffers a reduction of the wave packet when a succeeding measurement is made. It is shown, completely within the conventional framework, that the sense of this time asymmetry can be reversed and a retroductive formalism introduced which is based upon the fact that only the final state is known. Moreover, if both the initial and final states of a set of measurements are fixed, a completely time symmetric formalism can be constructed for the time interval between these given states. The selection of the predictive scheme can be made with the help of macroscopic considerations and consequently it appears that the basic time asymmetry is not a consequence of conventional quantum physics including measurement.

ISSN:0002-9505    

DOI:10.1119/1.1973012

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP

摘要:

The electromagnetic field transforms as an antisymmetric second-rank tensor under Lorentz transformations. Starting with the electric field and relativity, what assumptions are required to obtain this result are considered, as well as how the existence of the magnetic field and some of its properties follow from the transformation law.

ISSN:0002-9505    

DOI:10.1119/1.1973013

出版商:American Association of Physics Teachers    

年代:1966

数据来源: AIP