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Superconducting bearings promise superior performance in certain scientific and technological applications. One application is in an orbital equivalence principle experiment, where linear bearings of extreme smoothness and small friction are required

In the framework of Rastall's conservative program for the construction of gravitation theory we present a variant of modified classical gravitation theory based on Einstein's energy-mass equivalence principle. We pursue further the special-relativistic arguments and obtain a theory for the static spherically-symmetric gravitation field that is based only on the well-established physical principles and accounts for all experimental tests known in gravitation. Some astrophysical consequences of the modified classical gravitation theory (e.g., the non-existence of black holes, the creation of real particles in a strong gravitation field) are also discussed.

Equations of motion for point-like test masses subjected to Yang-Mills-Lorentz and gravitational forces are derived from geodesic motion in the multidimensional space of a non-Abelian Kaluza-Klein theory with vanishing cosmological constant.

In a previous paper [1] the author proposed a new linear nonmetric theory of gravitation in a plane space by giving the Einstein values for the four effects of the general theory of relativity (GTR). The field and motion equations were constructed on the basis of Lagrangians selected by the Hamilton principle. The gravitational field potential (GF) was a symmetric tensor of the second rank ψμν. A nonlinear extension of the theory is carried out in this paper on the basis of a single Lagrangian of the GF interaction with matter fψμν Tμν + λψT, where Tμν is the energy-momentum tensor of matter including the GF, f and λ are arbitrary constants of the theory. Within the framework of the nonlinear theory which yields the Einstein values for the four GTR effects, an additional condition is obtained which is imposed on the five arbitrary constants of the theory from which the satisfiability of the weak equivalence principle for bulk bodies of electromagnetic structure follows.

We show herein that a formulation of the free-scalar-field theory in an expanding universe, based on the quantum equivalence principle (QEP), leads to a finite creation of particles at the expense of the gravitational field. In this formulation, the mean value of theT00 component of the energy-momentum tensor is divergent.

A set of equations representing the (generalized) laws of electromagnetism in a gravitational field for a class of nonmetric theories of gravity are written down. From these equations we calculate the center-of-mass acceleration of a composite test body, consisting of electromagnetically interacting charged point particles, in an external, spherically symmetric and static (SSS) gravitational field. Demanding that the weak equivalence principle be satisfied, so that contains no composition-dependent terms, puts severe constraints on the form of the original generalized equations. Indeed, the principle demands that the laws of electromagnetism in an (SSS) gravitational field take on a ''metric'' form. The observational constraints on the form of the (generalized) laws of electromagnetism from Eoetvoes experiments are also discussed.

An algebraic proof of the equivalence theorem, to all orders of perturbation theory, is obtained by applying the equations of motion repeatedly in a normal-product algorithm. It is shown that, for certain nonlocal transformations, the equivalence theorem can be maintained by introducing Faddeev-Popov ghosts. (AIP)

It is shown that the general theory of relativity is not satisfactory physical theory, since in it there are no laws of conservation for the matter and gravitational field taken together and it does not satisfy the principle of correspondence with Newton's theory. In the present paper, we construct a new theory of gravitation which possesses conservation laws, can describe all the existing gravitational experiments, satisfies the correspondence principle, and predicts a number of fundamental consequences.

It is attempted to construct a theory of static gravitation in empty space on the basis of only special relativity and equivalence. The derivation contains three steps: fixation of time coordinate, derivation of field equation, and fixation of space coordinates. First, by conservation of energy it is shown that static gravitation is governed by one function, 2χ(r) = log g00. A universal time coordinate is found, and the redshift obtained. The components of the line element are fixed, except for its spatial part. Second, the field equation for χ is derived by equivalence with the accelerated Moller box. These two steps remain in accordance with general relativity. Third, universal spatial coordinates are found by common measurements by all possible test particles, leading to harmonic and isotropic coordinates. The result is in agreement with the Schwarzschild solution to first order beyond Newtonian gravitation. The second-order disagreement with general relativity is discussed.

The theoretical setting of the experimental study of gravitation is indicated and a brief account is given of experiments on gravitation from Newton onwards. The main content of the review comprises surveys of three groups of experiment: the investigation of the inverse square law, studies of the weak equivalence principle and determinations of the constant of gravitation. Attention is called to the reasons for the difficulties of carrying out experiments on gravitation. In summary, it is concluded that there is no evidence for deviations from general relativity and that gravitation is mainly a manifestation of the geometry of spacetime.

Pion-exchange contributions to the isoscalar part of the charge operator are studied using the equivalence theorem and time-dependent perturbation theory.

A discussion of the nouniqueness of physical laws and their invariance groups is illustrated by the construction of a physical theory (presented earlier) in which the law of motion of structureless and spinning particles is unified in the geometry of the manifold of the de Sitter groupSO(3,2). The theory has the structure of a non-Abelian Kaluza-Klein theory with very special properties resulting from the topology and noncompactness of the groups. The physical interpretation of the field equation is discussed. The physical requirement of equivalence of the interaction of spinning and orbiting systems, generally unconsidered in related theories, is here taken into account by the structure of the theory. The possibility of deviations from predictions of general relativity exists. Generalizations of the theoretical structure to higher dimensional groups are outlined and open the possibility for observations.

In many situations, because of the great influence of a surface layer on apparent resistivity values, the interpretation of electrical soundings may be very indeterminate, according to the “equivalence principle”. For these situations, an arrangement which includes an underground electrode has been proposed. With this method, the interpretative indeterminatecy may be often eliminated, as may be seen from the diagrams calculated for some typical situations.

A theory is developed describing the electromagnetic radiation from dielectric rods used as terminations to rectangular wave guides. The radiation patterns are computed from the fields due to equivalent magnetic and electric currents on the surfaces of the rods. These equivalent currents are determined by use of Schelkunoff's equivalence principle applied to approximate fields within the dielectric. Specific calculations are carried out for rods whose average dimensions are 0.9″×0.25″ and whose lengths vary from three to ten wave‐lengths. Experimental patterns are obtained for eight polystyrene rods, some of which are variable in length. Agreement with theory is found for rods from three to six wave‐lengths long; differences between experiment and theory are discussed.

This study concerns a non-linear system described by three generalized coordinates, two of which have the same natural frequency. Resonant harmonic excitation acting upon one of the multiple coordinates may cause both to be much larger than the remaining secondary one. The responses of this system are shown to have the same stability behavior as those of a standard non-linear system with two degrees of freedom, provided that the amplitude-frequency relations for both systems are identical.

Mechanical and birefringent properties of plasticized polyvinyl ehloride in the glass transition region were determined by means of quasistatic tests at different temperatures and sinusoidal oscillation tests at room temperature. In the former method, mechanical creep and photocreep tests were conducted at temperatures ranging from −80 to 115°F. The method of reduced variables (temperature‐time equivalence principle) was used to obtain continuous curves for relaxation modulus and stress fringe value corresponding to room temperature and extending up to 24 decades of time. The resulting curves show a broad transition region for the material. The shift function was plotted versus temperature and was found to be about the same for both mechanical and optical properties. Short‐time (dynamic) properties obtained by the temperature‐time equivalence principle were compared with those obtained at room temperature by direct sinusoidal oscillation tests at different frequencies. The complex modulus and complex stress fringe value were determined as functions of frequency and converted to a relaxation modulus and stress fringe value as functions of time by means of an approximate interrelationship. The validity of the temperature‐time equivalence principle in this case was proven by the good agreement between these results and those obtained from creep tests at different temperatures.

The effect of normal pressure and rate dependences of elastomer friction in the glass transition region has been investigated. The results confirm the absence of a maximum on the rate dependence of the friction coefficient and demonstrate the possibility of applying the temperature-time equivalence principle to the description of the rate dependence of the friction coefficient at increased pressures.

A simple derivation of the general relativistic correction to planetary orbits is given, without explicit reference to Einstein’s field equations. The calculation is compared to Schiff’s investigation of the bending of light. Restrictions on the line element of curved space, which follow from the weak and strong equivalence principles are discussed. The weak equivalence principle and the weak field approximation are exploited to give a simple derivation of the correction to planetary motion in the Brans-Dicke theory.

The present paper deals with the analysis of the meaning and of the role of space-time quanta. A consistent mathematical description of the non-transitive binary ‘equivalence’ is obtained. In connection with the existence of certain threshold velocities some peculiarities of the high-energy behaviour of scattered nucleons are explained.

The concepts of inverse and left inverse systems, weakly equivalent and strongly equivalent systems, and discretetime and finite memory systems are examined. Various relations between these concepts are found, and the role of the decomposition property of the system input-output state relation is investigated. Among the results obtained are 1) under suitable controllability assumptions, left inverse systems are inverse systems, 2) weakly equivalent finite memory systems with the decomposition property are strongly equivalent, and 3) finite-state systems with the decomposition property have finite memory.

Harvey has argued that within the framework of the Nordstrom theory a spinning top falls with the wrong gravitational acceleration, and concludes from this that the “weak equivalence principle” does not define an interesting or significant class of gravitational theories. It is shown that Harvey's spinning top is not physically realizable, and it is proved that physically realizable bodies, if isolated and sufficiently small, fall with the same gravitational acceleration in the Nordstrom theory.

An equivalence relation which extends, and incorporates into the rational approximation, the basic ideas of some Russian workers is derived. This equivalence relation takes accurate account of the dependence on the Dancoff correction. The narrow resonance approximation is assumed throughout.

It is shown that the invariance of the S -matrix under the addition of a 4-divergence to the Lagrangian density of a system of interacting fields allows one to derive various equivalence theorems in a very simple manner. A simple illustration of this method is followed by a discussion of a class of derivative couplings for which equivalence theorems can be proved. Applications of some exact equivalence theorems are then made to a renormalizability problem and to the question of the generation of vector fields from local gauge invariance. Finally, the same invariance property is employed to prove the theorem that point transformations of the fields leave the S -matrix unchanged.

The Hole-Equivalence Principle for partly filled shells in which 2p electrons can be placed is discussed. Conjugated functions in corresponding configurations are classified according to the irreducible representations of the symplectic group Sp2p of order 2p. It is shown that the concept of seniority is related to the irreducible representations of this group, independent of the one-electron states determining the partly filled shell. In addition the parity of the half-closed shell states is discussed.

A theory of the gravitation field is proposed in connection with a new spinorial formulation of EINSTEIN'S equivalence principle and HEISENBERG'S unified quantum theory of fields. In the gravitation theory the gravitational field is given by the coefficients hAi (xl) of the matrix of the anholonomic non-Lorentzian transformations from the Lorentzian metric ηAB to the physical metric gik (xl) of the Riemannian space-time V4. The field equations and the commutation rules for the hAi are working in the Lorentzian space. The metric of the Riemannian V4 is given by the average gik = 〈|hAi, hBk|〉ηAB. For all matter fields (and for HEISENBERG's “Urfeld”) the field equations are equations in this Riemannian V4. The interaction between the gravitational field hAi and the matter-tensor is given by a potential-like coupling-term. We prove that this new theory of gravitation gives for makroscopic matter the same linear approximation equations like general relativity and that a perihel-motion δφ ≈ 76 δφ EINSTEIN results in the second approximation. But, we are finding essential differences to general relativity for the theory of gravitation radiation and for the theory of interaction of matter with strong gravitation fields.

The authors attempt to prove the equivalence theorem for S-matrix elements. The dynamical aspect-which ensures that the dynamics is coordinate independent, and requires care in preservation of the order of non-commuting operators-and the kinematical aspect, which ensures that asymptotic fields are unchanged are distinguished. It is the latter condition which causes difficulty; whilst trivial for the free field the authors give non-trivial examples which violate it.

We define a derivation operation working on hybrid objects which are tensors under theEinstein group of coordinate transformations and under theLorentz group of transformations of reference systems. With these general covariant derivations we formulate the principle of the equivalence of theEinstein- and of theLorentz-covariant representations of the physical laws. This principle means the general covariant constance of the metric tetradsh i A (Weyl's lemma).

A comparative study of the expressions for radiation pattern of a circular dielectric rod aerial excited in the HE11 mode as obtained1 by the Schelkunoff's equivalence principle and by the application of Huyghen's principle over the whole rod2 shows that in the Φ = 0° and Φ = 90° planes, the beamwidth of the major lobe and the structure of the radiation pattern differ in the former case but are the same in the latter case. It is also shown that Halliday and Kiely's theory,3 also based on Huyghen's ray theory, does not indicate any variation in these factors in the two planes. This is justified due to the vector nature of the Schelkunoff's principle and the scalar nature of the original Huyghen's principle.

The paper presents results of shape optimization of underground structure. First, the objective function is proposed based on the energetic equivalence principle. The excavation is replaced, within the approach proposed, by an artificial very compliant material and the optimal shape of the excavation is postulated as the one that minimizes the energy of volumetric strain cumulated in it. The solution is looked for using the stochastic optimization approach, namely the simulated annealing (SA) procedure. A soil-steel bridge structure with different loads and boundary conditions is investigated. The results representing the optimized shapes of the structures examined are presented.

Based on data from the supernova SN 1987A it is shown that the Einstein equivalence principle is confirmed for electron neutrinos and their antiparticles to one part per million provided at least one of the events is due to ${\ensuremath{\nu}}_{e}$e scattering. Bounds on the strengths of new galactic-range forces coupling to neutrinos (of nonzero mass) and to matter are also deduced.

By considering the relationship between a freely falling frame and a local Lorentz frame, we propose a new expression of Einstein's equivalence principle (EEP). According to it, some feasible experiments should be done to test EEP. We point out that the effect of the magnetic-type gravitational counterpart of the Aharonov-Bohm experiment is too small to be detected now.

The equivalence between direct-interaction theories and non-linear field theories is discussed on a classical (non-quantum) basis. It is shown that to have such an equivalence three-body forces must be introduced, if there is not coupling between different interactions, in the action-at-a-distance framework. Finally a new type of Poincare-invariant theory containing three-body forces is proposed.

One reason the Lagrangian density for the gravitational field must contain both the co- and contra-variant field variables is because the part for the «free» gravitational field √−g R contains both of these variables. The same situation does not occur in general for the matter fields because Λ contains besides the matter-field variables the gravitational-field variables.

Mach's principle as frequently described may be illusory, but attempts at deeper formulations are difficult to interpret.

Applying the method of change of variable to the differential equation governing nonuniform transmission lines (NUTL's), an equivalence principle for NUTL's is given, which may be considered as a generalization of the one previously described by Hellstrom [1] and which includes three methods of equivalent transformation for NUTL's.

The serendipitous observation of neutrinos and light from the recent supernova in the Large Magellanic Cloud has provided a wealth of new information about stellar collapse and about neutrinos. It is pointed out that, in addition, the nearly simultaneous arrival of the photons and neutrinos after a journey of some 160 000 yr provides a new, stringent test of the Einstein equivalence principle on intergalactic distance scales. The relativistic time delays of the photons and neutrinos from SN1987A caused by the gravitational field of our Galaxy are compared, and it is shown that they are equal, to an accuracy of approximately 0.2% of the predicted delay.

In order to attempt a global description of gravitation, one has to consider the entire cosmos, rather than infinitesimal space—time regions. Unfortunately, our experience from nongravitational physics is in the first instance of no use in this approach, as the physics in question has a local, field-theoretical, character. We are left with only one possibility : Start with a global formulation of gravitational law, and afterwards attempt to relate it to local, gravitational as well as nongravitational, physics.

On 20 March 1916, Albert Einstein’s paper on ‘The foundations of the theory of general relativity’ arrived at the Annalen der Physik.165 A long paper of more than fifty printed pages, it established the theory of gravitation within the framework of general relativity, and gave a complete account of the fundamental principles and the most important consequences.

This article summarizes the results obtained from several studies conducted by the author, concerning the calculation of doses received at moving radiation fields generated by photon-emitting radiation sources. An attempt is made to provide a methodology for the aforementioned calculation, in those cases where simple geometries are involved, using what is described as the "duality principle" and the concept known as "equivalent static system" (EES), so as to be able to draw upon the wealth of data available in reference material relating to static systems.