摘要:

Novikov has developed a reference system built around radially moving geodesic clocks that allows particle and light signal trajectories to be followed across the Schwarzschild radiusRs. We utilize Novikov’s reference system to demonstrate that in any light cone insideRs, there exists a naturally occurring limiting timelike geodesic that divides the light cone into two parts. The limiting geodesic corresponds to a ‘‘last’’ particle that falls from, or rises to,Rs. It is seen in all coordinate systems that allow trajectories to be followed insideRs. We show how the limiting geodesic appears in Kruskal–Szekeres coordinates and in a geodesic clock analog to Eddington–Finkelstein coordinates. Limitations on the range of validity of the Novikov reference system are also described.

ISSN:0002-9505    

DOI:10.1119/1.17907

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

The exponential decay law is a consequence of the choice of the ‘‘Breit–Wigner’’ energy distribution when the integration over the energy is extended from −∞ to +∞. We explain why the Breit–Wigner function is the natural choice and study by the method of steepest descent and by direct integration how an integration over the physically relevant positive energy spectrum affects the decay law.

ISSN:0002-9505    

DOI:10.1119/1.18091

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

The penetration probability of the quantum harmonic oscillator into the classically forbidden region is examined in the limit of large quantum numbers using analytical methods. An expression is derived for the asymptotic form of the penetration probability, and is shown to be in good agreement with an earlier result obtained by numerical methods. The asymptotic form of the probability density in the region between the classical turning points is also presented and found to have a simple physical interpretation.

ISSN:0002-9505    

DOI:10.1119/1.17908

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

This paper elucidates how many‐particle quantum hydrodynamic equations underlie the virial formula, including its surface pressure term. It shows the relation of the field variables to the particle Wigner function, proposes a many‐particle ‘‘liquid’’ model to approximate these variables, and discusses its application to electrons in semiconductor nanostructures.

ISSN:0002-9505    

DOI:10.1119/1.17909

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

Ideal thermoacoustic heat pumps deliver a maximum heat flux if they operate at 1/3 of the Carnot efficiency CODCar=Tc/(Th−Tc). The best position for the stack is about λ/8 from the closed end.

ISSN:0002-9505    

DOI:10.1119/1.17910

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

The expression for the energy of a system of charges and linear dielectrics is divided into terms arising from the coulomb energy of subsystems of free and bound charges, from their interaction, and from the energy stored in the dielectric in the process of creating the bound charges.

ISSN:0002-9505    

DOI:10.1119/1.18073

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

The electric and magnetic fields of a line charge of finite length uniformly moving along its axis are derived by using retarded field integrals and also by using transformation equations of the special relativity theory. Both derivations yield the same field equations, although the derivation methods are drastically different. In particular, whereas transformation equations generally associated with Lorentz length contraction are crucial for the relativistic derivation, Lorentz contraction is not used in the retarded field derivation. On the other hand, although the retarded field derivation is based on the idea that retardation in the propagation of electromagnetic effects is a fundamental electromagnetic phenomenon, the relativistic derivation does not take retardation into account. An examination of the two solutions indicates that the field equations obtained classically and relativistically are identical because retardation is implicit in relativistic transformations.

ISSN:0002-9505    

DOI:10.1119/1.17911

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

The variational method is used to calculate the ground state energy of the hydrogen atom confined within hard spherical and cylindrical surfaces, for an atomic nucleus which is off the center of symmetry of the confining boundary. It is shown that the wave function for the free hydrogen atom in spherical coordinates (referred to the center of symmetry of the confining geometry) can be used without further assumptions to construct the trial wave function systematically. The latter is assumed to be the product of the free wave function and a simple cutoff function that satisfies the appropriate boundary conditions. We compute the ground state energy for these systems and the results are in good agreement with more sophisticated calculations, thus proving the reliability of the proposed strategy.

ISSN:0002-9505    

DOI:10.1119/1.17912

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

We use reduced density matrix methods of general applicability in many‐body physics to study one‐particle properties of a simple, soluble quantum system, the fermionic anharmonic oscillator. The time evolution of a general initial state of this system is worked out and analyzed in detail from this point of view. We use a canonical transformation of the Bogoliubov type to enhance the power of the one‐particle reduced description and show that the reduced density matrix corresponds in general to a statistical mixture even if the state of the entire many‐body system is described in terms of a state vector (pure state).

ISSN:0002-9505    

DOI:10.1119/1.17913

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.17914

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP