摘要:

The bound electron self‐energy or Lamb shift is calculated in nonrelativistic quantum electrodynamics. Retardation is retained and also the σ⋅Bradinteraction previously dropped in other nonrelativistic approaches is kept. The results are finite without the introduction of a cutoff, and they lead to a Lamb shift in hydrogen of 1030.9 MHz, which is about 2.5% less than the standard relativistic calculation.

ISSN:0002-9505    

DOI:10.1119/1.12608

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

The Poincaré group, the group of transformations of the plane which preserve the Minkowski distance between points, is derived as compositions of suitably defined reflections in straight lines. It is shown that any such transformation must be one of four types.

ISSN:0002-9505    

DOI:10.1119/1.12609

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

For a ball to roll without slip across the surface of a rotating platform, a frictional force of the formAωd×v is required, whereAis a known constant, ωdis the platform’s angular velocity, and v is the particle’s velocity relative toinertialspace. Since this force is of the same form as that experienced by a charged particle moving through a magnetic field, the ball executes only closed circular orbits. Other similarities to the charged particle problem are easily demonstrated: for example, drift velocities are produced normal to any external force lying in the plane of the disk, and an adiabatic invariant can be defined for the case when the disk changes its spin rate.

ISSN:0002-9505    

DOI:10.1119/1.12610

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

By analyzing the decay of a compound system into two praticles, we show that measurements on particle 1 will define with an arbitrary degree of precision the coordinate and momenta of particle 2 at times large compared with the lifetime of the compound system, i.e., when the two particles no longer interact. Thus we have an example of the Einstein–Podolsky–Rosen argument in which all the requirements of quantum mechanics are met. Criticism of the point of view they present should then center on their epistemological position (such as their definition of physical reality) rather than on their use of the quantum‐mechanical formalism.

ISSN:0002-9505    

DOI:10.1119/1.12611

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

Speed‐of‐light determinations by the principle first used by Römer gain their meaning either from an assumed constancy of this speed for all directions or else from an assumed constancy for all closed paths. The observed result, in either case, evaluates the corresponding constant. It is therefore incorrect to hold that Römer’s methodobjectivelygives a one‐way speed. These circumstances are illustrated by analysis of a laboratory experiment proposed by G. B. Brown.

ISSN:0002-9505    

DOI:10.1119/1.12612

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

We discuss a relativistic particle affected simultaneously by two static potentials, a Lorentz scalar and the time component of a four‐vector. We show that the scalar potential has effects on the motion of a particle that are distinctively different from those of a four‐vector potential. With the aid of an example we show that, in both classical and quantum mechanics, there are two inequivalent but compatible criteria of nonrelativistic behavior: (mean) kinetic energy much smaller than rest energy and nonrelativistic potential energy independent of total energy. The second of these is the correct condition for use of nonrelativistic methods, but it is the first that is usually invoked to justify their use. The two criteria are equivalent only when the scalar potential has a (mean) value much less in magnitude than the particle’s rest energy. If this condition is not satisfied, nonrelativistic formalisms such as ordinary Newtonian mechanics and the Schrödinger equation may be inadequate even ifv/cis small. On the other hand, it is possible that a largeSmay permit relativistic energy relations to be written in a nonrelativistic form even ifv/cis not small. Such an influence of the size of the scalar potential on what is considered nonrelativistic behavior is unfamiliar and is rarely mentioned in textbooks and other publications. In our opinion, it should be better known.

ISSN:0002-9505    

DOI:10.1119/1.12613

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.12615

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.12616

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.12660

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.12662

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP