On the geometrization of electrodynamicsVargas, Jose
doi: 10.1007/BF00733354pmid: N/A
This paper develops the conjecture that the electromagnetic interaction is the manifestation of the torsion Ωμ of spacetime. This conjecture is made feasible by the natural separation of the connection ω
μ
v
into “gravitational” and “electromagnetic” parts α
μ
v
and β
μ
v
, respectively, related to the metric and to the torsion. When α
μ
v
is neglected in front of β
μ
v
, the affine geodesics are shown to become the equations of motion of charged particles with Lorentz force, for an appropriate choice of Ωμ. Since β
μ
v
contains the factor q/m, neutral particles do not see the torsional part of the connection and behave as if Ωμ were zero, i.e., as in Einstein's theory of gravity (the same effect is obviously obtained for charged particles when β
μ
v
《 α
μ
v
).
An empirical, purely spatial criterion for the planes ofF-simultaneityColeman, Robert; Korte, Herbert
doi: 10.1007/BF00733356pmid: N/A
The claim that distant simultaneity with respect to an inertial observer is conventional arose in the context of a space-and-time rather than a spacetime ontology. Reformulating this problem in terms of a spacetime ontology merely trivializes it. In the context of flat space, flat time, and a linear inertial structure (a purely space-and-time formalism), we prove that the hyperplanes of space for a given inertial observer are determined by a purely spatial criterion that depends for its validity only on the two-way light principle, which is universally regarded as empirically verified. All (empirically determined) “spacetime” entities, such as the conformal structure or light surface equation, are used in a purely mathematical manner that is independent of and hence isneutral with respect to the ontological status that is ascribed to them. In this regard, our criterion is significantly stronger than thespacetime criterion recently advanced by D. Malament, which appeals explicitly to the conformal orthogonality of spacetime vectors and to the invariance of the conformal-orthogonal structure of spacetime under the causal automorphisms of spacetime. Once the hyperplanes of space for a given inertial observer have been determined by our empirical and purely spatial criterion, the following holds: there exists one and only one
$$\vec \varepsilon $$
-synchronization procedure, namely the standard procedure proposed by Einstein, such that the planes of common time are thesame as the nonconventional hyperplanes of space for the inertial observer. It follows that our criterion provides an empirical even if indirect method for determining that the one-way speed of light is the same as the average two-way speed of light. In addition, two inertial observers that are not at rest with respect to each other necessarily havedifferent hyperplanes of space, and consequently their respective spatial views cannot be encompassed in a single three-dimensional space. Hence, our purely spatial criterion provides an empirical motivation for adopting the more comprehensive spacetime ontology.
On the indistinguishability of classical particlesFujita, S.
doi: 10.1007/BF00733357pmid: N/A
If no property of a system of many particles discriminates among the particles, they are said to be indistinguishable. This indistinguishability is equivalent to the requirement that the many-particle distribution function and all of the dynamic functions for the system be symmetric. The indistinguishability defined in terms of the discrete symmetry of many-particle functions cannot change in the continuous classical statistical limit in which the number density n and the reciprocal temperature β become small. Thus, microscopic particles like electrons must remain indistinguishable in the classical statistical limit although their behavior can be calculated as if they move following the classical laws of motion. In the classical mechanical limit in which quantum cells of volume (2πħ)3 are reduced to points in the phase space, the partition functionTr{exp(−βĤ) for N identical bosons (fermions) approaches (2πħ)−3N(N!) ∫ ... ∫ d3r1 d3p1 ... d3rN d3pN
exp(−βH). The two factors, (2πħ)−3N and (N!)−1, which are often added in anad hoc manner in many books on statistical mechanics, are thus derived from the first principles. The criterion of the classical statistical approximation is that the thermal de Broglie wavelength be much shorter than the interparticle distance irrespective of any translation-invariant interparticle interaction. A new derivation of the Maxwell velocity distribution from Boltzmann's principle is given with the assumption of indistinguishable classical particles.
Can one have a universal time in general relativity?Rosen, Nathan
doi: 10.1007/BF00733358pmid: N/A
The rest-frame of the universe determines a universal, or absolute time, that given by a clock at rest in it. The question is raised whether one can have a satisfactory universal time in general relativity if a gravitational field is present, i.e., whether there are coordinates such that the coordinate time is the time given everywhere by a clock at rest and they provide the correct description of our everyday experience. Several attempts are made to find such coordinates, but the results are unsatisfactory. The question is still open, but it may be that there is no significance to such a universal time in general relativity, because to have a clock at rest in a gravitational field requires nongravitational forces.
Gravitation theory in the spacetimeR×S 3Zet, G.; Pasnicu, C.; Agop, M.
doi: 10.1007/BF00733359pmid: N/A
A geometric formulation of the gravitation theory in the spacetime R × S
3
is given. A linear connection is introduced on the tangent bundle T(R × S
3
) and then the connection coefficients and the Riemann curvature tensor are calculated. It is shown that their expressions differ from those of Carmeli and Malin [Found. Phys.17, 407 (1987)] by supplementary terms due to the noncommutativity of derivatives used on the spacetime R × S
3
. The Einstein field equations are written as usually and a comparison with other results is given. Finally, some observations about a possible gauge theory of gravitation in the spacetime R × S
3
are made.
Quantum logics with the existence propertySchindler, Christian
doi: 10.1007/BF00733360pmid: N/A
Aquantum logic (σ-orthocomplete orthomodular poset L with a convex, unital, and separating set Δ of states) is said to have theexistence property if the expectation functionals onlin(Δ) associated with the bounded observables of L form a vector space. Classical quantum logics as well as the Hilbert space logics of traditional quantum mechanics have this property. We show that, if a quantum logic satisfies certain conditions in addition to having property E, then the number of its blocks (maximal classical subsystems) must either be one (classical logics) or uncountable (as in Hilbert space logics).