Comment on “On the general relativistic framework of the Sagnac effect” EPJC 79:187

Abstract The Sagnac effect is usually considered as being a relativistic effect produced in an interferometer when the device is rotating. General relativistic explanations are known and already widely explained in many papers. Such general relativistic approaches are founded on Einstein’s equivalence principle (EEP), which states the equivalence between the gravitational “force” and the pseudo-force experienced by an observer in a non-inertial frame of reference, included a rotating observer. Typically, the authors consider the so-called Langevin-Landau-Lifschitz metric and the path of light is determined by null geodesics. This approach partially hides the physical meaning of the effect. It seems indeed that the light speed varies by $$c\pm \omega r$$ c ± ω r in one or the other direction around the disk. In this paper, a slightly different general relativistic approach will be used. The different “gravitational field” acting on the beam splitter and on the two rays of light is analyzed. This different approach permits a better understanding of the physical meaning of the Sagnac effect.

Download Full-text

Erratum to: Comment on “On the general relativistic framework of the Sagnac effect” EPJC 79:187

The European Physical Journal Plus ◽

10.1140/epjp/s13360-020-00590-7 ◽

2020 ◽

Vol 135 (8) ◽

Author(s):

H. Ramezani-Avala

Keyword(s):

Sagnac Effect ◽

General Relativistic ◽

Relativistic Framework

Download Full-text

Hermann Weyl's Analysis of the “Problem of Space” and the Origin of Gauge Structures

Science in Context ◽

10.1017/s0269889704000080 ◽

2004 ◽

Vol 17 (1-2) ◽

pp. 165-197 ◽

Cited By ~ 21

Author(s):

Erhard Scholz

Keyword(s):

General Relativity ◽

Dirac Equation ◽

A Priori ◽

Group Extension ◽

Central Idea ◽

German Word ◽

General Relativistic ◽

Empirical Turn ◽

Relativistic Framework ◽

Internal Symmetries

Hermann Weyl (1885–1955) was one of the early contributors to the mathematics of general relativity. This article argues that in 1929, for the formulation of a general relativistic framework of the Dirac equation, he both abolished and preserved in modified form the conceptual perspective that he had developed earlier in his “analysis of the problem of space.” The ideas of infinitesimal congruence from the early 1920s were aufgehoben (in all senses of the German word) in the general relativistic framework for the Dirac equation. He preserved the central idea of gauge as a “purely infinitesimal” aspect of (internal) symmetries in a group extension schema. With respect to methodology, however, Weyl gave up his earlier preferences for relatively a-priori arguments and tried to incorporate as much empiricism as he could. This signified a clearly expressed empirical turn for him. Moreover, in this step he emphasized that the mathematical objects used for the representation of matter structures stood at the center of the construction, rather than interaction fields which, in the early 1920s, he had considered as more or less derivable from geometrico-philosophical considerations.

Download Full-text

Relativistic Models for a GAIA-Like Astrometry Mission

International Astronomical Union Colloquium ◽

10.1017/s0252921100000452 ◽

2000 ◽

Vol 180 ◽

pp. 314-319 ◽

Cited By ~ 4

Author(s):

F. de Felice ◽

A. Vecchiato ◽

B. Bucciarelli ◽

M.G. Lattanzi ◽

M. Crosta

Keyword(s):

Reference Frame ◽

Fundamental Physics ◽

Accurate Knowledge ◽

Adopted Model ◽

Relativistic Approach ◽

General Relativistic ◽

Relativistic Models ◽

Relativistic Parameter ◽

Relativistic Framework ◽

Better Than

A non-perturbative general relativistic approach to global astrometry was developed by de Felice et al. (1998) to handle satellite astrometry data in a genuine relativistic framework. In this contribution, the framework above has been further exploited to account for stellar motions and parallax. Because of the relevance that accurate knowledge (to 10−5 or better) of the relativistic parameter γ has to fundamental physics, a Parametrized Post-Newtonian (PPN) model has also been implemented, which allows the direct estimation of γ along with the astrometric parameters. These models have been tested on end-to-end simulations of the mission GAIA. The results show that, within the limitation of the simulation and the assumptions of the adopted model, measurements accurate to 100 μarcsec of large arcs among stars repeated over a few years can be modelled to establish a dense reference frame with a precision of a few tens of μarcseconds. Moreover, our experiments indicate that γ can be estimated to better than 10−6.

Download Full-text

Anisotropic fermionic matter in a general relativistic framework and dynamic stability of anisotropic systems

The Fourteenth Marcel Grossmann Meeting ◽

10.1142/9789813226609_0294 ◽

2017 ◽

Author(s):

Giuseppe Alberti ◽

Marco Merafina

Keyword(s):

Dynamic Stability ◽

General Relativistic ◽

Anisotropic Systems ◽

Relativistic Framework

Download Full-text

Vortex pinning in the superfluid core of relativistic neutron stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab606 ◽

2021 ◽

Vol 503 (1) ◽

pp. 1407-1417

Author(s):

Aurélien Sourie ◽

Nicolas Chamel

Keyword(s):

Neutron Stars ◽

Outer Core ◽

Vortex Pinning ◽

Global Dynamics ◽

Mutual Friction ◽

Dynamical Equations ◽

General Relativistic ◽

Superfluid Core ◽

Relativistic Framework

ABSTRACT Our recent Newtonian treatment of the smooth-averaged mutual-friction force acting on the neutron superfluid and locally induced by the pinning of quantized neutron vortices to proton fluxoids in the outer core of superfluid neutron stars is here adapted to the general-relativistic framework. We show how the local non-relativistic motion of individual vortices can be matched to the global dynamics of the star using the fully 4D covariant Newtonian formalism of Carter & Chamel. We derive all the necessary dynamical equations for carrying out realistic simulations of superfluid rotating neutron stars in full general relativity, as required for the interpretation of pulsar frequency glitches. The role of vortex pinning on the global dynamics appears to be non-trivial.

Download Full-text

Shear-free conditions of a Chaplygin-gas-dominated universe

International Journal of Geometric Methods in Modern Physics ◽

10.1142/s0219887821501929 ◽

2021 ◽

pp. 2150192

Author(s):

Amare Abebe ◽

Mudhahir Al Ajmi ◽

Maye Elmardi ◽

Hemwati Nandan ◽

Noor ul Sabah

Keyword(s):

General Relativity ◽

Perfect Fluid ◽

Chaplygin Gas ◽

Current Investigation ◽

Free Condition ◽

General Relativistic ◽

Relativistic Framework ◽

Fluid Spacetimes

In this work, we revisit the shear-free conjecture of general relativity and study the well-known shear-free condition in the context of the Chaplygin-gas cosmology. It had been shown in previous investigations that, in the general relativistic framework, the matter congruences of shear-free perfect fluid spacetimes should be either expansion-free or rotation-free. Our current investigation, however, indicates that a universe dominated by a Chaplygin-gas can allow a simultaneous expansion and rotation of the fluid provided that certain non-trivial conditions, which we derive and describe in what follows, are met. We also show that, in the appropriate limiting cases, our results reduce to the expected results of dust spacetimes which can only expand or rotate, but not both, at the same time.

Download Full-text