arXiv subjects

Matteo Luca Ruggiero

Publications and source records attributed to Matteo Luca Ruggiero.

At least 19 recordsLinked to original sources

arXiv2026

Non-trivial boundary conditions in general-relativistic models

We propose an alternative interpretation of dark matter effects within the framework of General Relativity. In particular, we suggest that, in astrophysical and cosmological contexts, different initial assumptions about a system inevitably lead to different interpretations of the same phenomena. As a concrete example, we examine self-gravitating systems composed of an axially symmetric rotating dust fluid and show that effects typically attributed to the presence of additional matter, can instead be reproduced through an appropriate choice of initial and boundary conditions for the equations governing the system.

gr-qc↗

arXiv2025

Physics is simple only when analyzed locally

The definition of a reference frame in General Relativity is achieved through the construction of a congruence of time-like world-lines. In this framework, splitting techniques enable us to express physical phenomena in analogy with Special Relativity, thereby realizing the local description in terms of Minkowski spacetime in accordance with the equivalence principle. This approach holds promise for elucidating the foundational principles of relativistic gravitational physics, as it illustrates how its 4-dimensional mathematical model manifests in practical measurement processes conducted in both space and time. In addition, we show how, within this framework, the Newtonian gravitational force naturally emerges as an effect of the non-geodesic path of the reference frame.

physics.gen-ph↗

arXiv2025

Some geometrical aspects of gravitational waves using continuum mechanics analogy: State of the art and potential consequences

In this study, the authors employ the analogy between continuum mechanics and general relativity to investigate, from the perspective of elasticity and crystal plasticity, the deformations of space measured by LIGO/VIRGO interferometers during the passage of gravitational waves over Earth. The results of different innovative or existing mechanical models are compared with each other and compared with the observations in the framework of general relativity and Einstein-Cartan theory. Despite limitations, there is a convergence of results: the polarizations of gravitational waves can be viewed as expressions of an equivalent elastic media deformation tensor. Additionally, an anisotropy of space properties is unavoidable at the measurement point of the gravitational wave if we rely on the current first-order general relativity, which predict that gravitational waves generate deformations only in transverse planes. It is demonstrated that the classical polarizations of general relativity can be associated with a state of pure torsion in the analogous elastic medium and acted upon by the rotation of massive bodies such as black holes. This approach involves a transverse isotropic medium composed of independent sheets that deform perpendicularly to the direction of propagation of these waves. Considering geometric torsion in general relativity, associated with plastic crystallography, allows for the examination of complementary polarizations in the direction of wave propagation. This makes it possible to connect these sheets and reconstruct a complete, coherent 3D environment.

gr-qc↗

arXiv2025

Gravitational lensing observables in stationary and axisymmetric solutions in general relativity

We investigate light propagation in self-gravitating systems composed of an axially symmetric, stationary, rotating dust fluid. These configurations are intrinsically relativistic, sustained entirely by their rotation, since no compact or finite dust distribution can exist under the same symmetry conditions in Newtonian gravity. In such systems, rotational effects arise from off-diagonal components of the spacetime metric, which are not negligible compared to their Newtonian counterparts. We analyze how these components affect the deflection angle of light, showing that they can be interpreted as contributing an additional effective mass. Moreover, their presence can, in principle, be detected through the characteristic asymmetry they induce in the images of background sources.

gr-qc↗

arXiv2025

Einstein's elevator and the principle of equivalence

We outline here the design, execution, and educational outcomes of an intervention inspired by Einstein's elevator thought experiment, intended to introduce secondary school students to the principle of equivalence, which is at the basis of the theory of General Relativity. We build an experimental version of Einstein's elevator, which simulated the effects of free-fall in an accelerated reference frame: a detailed description of the experimental apparatus and its construction is provided, highlighting the challenges and innovations in creating a simple yet functional setup using everyday materials.

physics.ed-ph↗

arXiv2024

On the low-energy limit of stationary and axisymmetric solutions in General Relativity

We study the low-energy limit of General Relativity in the presence of stationarity and axial symmetry, coupled to dust. Specifically, we demonstrate that differences between the dynamics of General Relativity and those of Newtonian gravity persist even in the weak-field and slow-motion regime. Notably, these differences are driven by dragging terms that are not necessarily small, as is typically the case in the well-known gravitomagnetic limit. To highlight this distinction, we use the concept of strong gravitomagnetism that we introduced in previous works. We provide a pedagogical discussion of how these discrepancies arise and outline a systematic procedure to solve the equations of motion for such systems. Furthermore, we present analytical results for specific cases and also give the general solution for the vacuum case. A particularly notable result is our demonstration of how General Relativity can naturally account for a Tully-Fisher-like relation.

gr-qc↗

arXiv2024

Quantum two-level systems and gravitational waves

We study the interaction between gravitational waves and a quantum two-level system consisting of a spin 1/2 particle using the formalism of the proper detector frame. This approach highlights the effects of gravitational waves on both the particles and the observer, emphasizing that only relative measurements can be made. Specifically, within this framework, the gravitational field of the waves is described using the gravitoelectromagnetic analogy. The interaction of the system is then determined by the gravitomagnetic field of the wave, which induces a time-dependent perturbation. We analyze this perturbation for both generic frequencies and resonance conditions, and discuss its implications.

gr-qc↗

arXiv2024

Effects of gravitational waves on electromagnetic fields

We focus on the interaction of a plane gravitational wave with electromagnetic fields and we describe this interaction in the proper detector frame where, thanks to the introduction of Fermi coordinates, it is possible to refer to directly measurable quantities. The presence of a gravitational field can be addressed in terms of an effective electromagnetic medium and, within this framework, we show that the coupling of pre-existing electromagnetic fields with the gravitational field of the wave gives rise to new effective currents. To assess the impact of these effects, we solve Maxwell's equations for some standard configurations of the electric and magnetic fields.

gr-qc↗

arXiv2024

Particle motion in a rotating dust spacetime: the Bonnor solution

We investigate the geometrical properties, spectral classification, geodesics, and causal structure of the Bonnor's spacetime [Journal of Physics A Math. Gen., \textbf{10}, 1673 (1977)], i.e., a stationary axisymmetric solution with a rotating dust as a source. This spacetime has a directional singularity at the origin of the coordinates (related to the diverging vorticity field of the fluid there), which is surrounded by a toroidal region where closed timelike curves (CTCs) are allowed, leading to chronology violations. We use the effective potential approach to provide a classification of the different kind of geodesic orbits on the symmetry plane as well as to study the helical-like motion aroud the symmetry axis on a cylinder with constant radius. In the former case we find that as a general feature for positive values of the angular momentum test particles released from a fixed space point and directed towards the singularity are repelled and scattered back as soon as they approach the CTC boundary, without reaching the central singularity. In contrast, for negative values of the angular momentum there exist conditions in the parameter space for which particles are allowed to enter the pathological region. Finally, as a more realistic mechanism, we study accelerated orbits undergoing friction forces due to the interaction with the background fluid, which may also act in order to prevent particles from approaching the CTC region.

gr-qc↗

arXiv2024

Stationary rotating and axially symmetric dust systems as peculiar General Relativistic objects

We study an exact solution of Einstein's equations describing a self-gravitating system, made of dust, distributed with axial symmetry and in stationary rotation, and we prove that this type of system has no Newtonian analogue. In a low-energy limit, its existence depends on the solution of a Grad-Shafranov equation in vacuum which can be interpreted as a Laplace equation for the toroidal component of the gravitomagnetic potential; in particular, in this system the relativistic rotational effects are of the order of magnitude of Newtonian ones. We therefore argue that this exact solution should contain singularities and discuss the possible consequences of using such a system as simplified models for galactic dynamics.

gr-qc↗

arXiv2023

A tale of analogies: gravitomagnetic effects, rotating sources, observers and all that

Gravitoelectromagnetic analogies are somewhat ubiquitous in General Relativity, and they are often used to explain peculiar effects of Einstein's theory of gravity in terms of familiar results from classical electromagnetism. Perhaps, the best known of these analogy pertains to the similarity between the equations of electromagnetism and those of the linearized theory of General Relativity. But the analogy is somewhat deeper and ultimately rooted in the splitting of spacetime, which is preliminary to the definition of the measurement process. In this paper we review the various approaches that lead to the introduction of a magnetic-like part of the gravitational interaction, briefly called gravitomagnetic and, then, we provide a survey of the recent developments both from the theoretical and experimental viewpoints.

gr-qc↗

arXiv2023

A note on the description of plane gravitational waves in Fermi coordinates

We use the formalism of Fermi coordinates to describe the interaction of a plane gravitational wave in the proper detector frame. In doing so, we emphasize that in this frame the action of the gravitational wave can be explained in terms of a gravitoelectromagnetic analogy. In particular, up to linear displacements from the reference world-line, the effects of the wave on test masses can be described in terms of a Lorentz-like force equation. In this framework we focus on the effects on time measurements provoked by the passage of the wave, and evaluate their order of magnitude. Eventually, we calculate the expression of the local spacetime metric in cylindrical coordinates adapted to the symmetries of the gravitational field and show its relevance in connection with the helicity-rotation coupling.

gr-qc↗

arXiv2023

Synchronization and Fundamental Time: a Connection between Relativity and Quantum Mechanics

An interesting connection between special relativity and quantum mechanics was put forward by Louis de Broglie, about 60 years ago, who focused on the link between synchronization in a rotating frame and the quantization of the angular momentum. Here we generalise his approach to curved spacetime, using the gravitoelectromagnetic analogy, which can be applied to describe the weak gravitational field around rotating sources, and give a new interpretation of the results.

gr-qc↗

arXiv2023

Status of the GINGER project

Large frame Ring laser gyroscopes, based on the Sagnac effect, are top sensitivity instrumentation to measure angular velocity with respect to the fixed stars. GINGER (Gyroscopes IN GEneral Relativity) project foresees the construction of an array of three large dimension ring laser gyroscopes, rigidly connected to the Earth. GINGER has the potentiality to measure general relativity effects and Lorentz Violation in the gravity sector, once a sensitivity of $10^{-9}$, or better, of the Earth rotation rate is obtained. Being attached to the Earth crust, the array will also provide useful data for geophysical investigation. For this purpose, it is at present under construction as part of the multi-components observatory called Underground Geophysics at Gran Sasso (UGSS). Sensitivity is the key point to determine the relevance of this instrument for fundamental science. The most recent progress in the sensitivity measurement, obtained on a ring laser prototype called GINGERINO, indicates that GINGER should reach the level of 1 part in $10^{11}$ of the Earth rotation rate.

gr-qc↗

arXiv2023

Can General Relativity play a role in galactic dynamics?

We use the gravitoelectromagnetic approach to the solutions of Einstein's equations in the weak-field and slow-motion approximation to investigate the impact of General Relativity on galactic dynamics. In particular, we focus on a class of the solutions for the gravitomagnetic field, and show that, contrary to what is expected, they may introduce non negligible corrections to the Newtonian velocity profile. These are the homogeneous solutions (HS) for the gravitomagnetic field, i.e. solutions with vanishing matter currents. We show how recent results about galactic dynamics are connected to this class of solutions.

gr-qc↗

arXiv2022

Galactic Dynamics in General Relativity: the Role of Gravitomagnetism

It is a well known fact that, in the absence of Dark Matter, the observation of the rotation curves of galaxies cannot be explained in terms of Newtonian gravity. Rotation curves become flat in the outer regions, in contrast to what is expected according to Keplerian motion. Far from the galactic center, the gravitational field is supposed to be weak enough so we expect to be able to use Newtonian Gravity; however, even in the weak-field approximation, there are general relativistic effects without a Newtonian counterpart, such as the gravitomagnetic effects originating from mass currents. Using the gravitoelectromagnetic approach to the solution of Einstein equations in the weak-field and slow-motion approximation, we discuss some simple arguments that suggest the surprising result that gravitomagnetic effects may have a relevant role in better understanding the impact of Dark Matter on galactic dynamics. In addition, treating matter as a fluid of dust, we study the influence of post-Newtonian effects on the fluid vorticity.

gr-qc↗

arXiv2022

GINGER

In this paper, we outline the scientific objectives, the experimental layout, and the collaborations envisaged for the GINGER (Gyroscopes IN GEneral Relativity) project. The GINGER project brings together different scientific disciplines aiming at building an array of Ring Laser Gyroscopes (RLGs), exploiting the Sagnac effect, to measure continuously, with sensitivity better than picorad/ s, large bandwidth (ca. 1 kHz), and high dynamic range, the absolute angular rotation rate of the Earth. In the paper, we address the feasibility of the apparatus with respect to the ambitious specifications above, as well as prove how such an apparatus, which will be able to detect strong Earthquakes, very weak geodetic signals, as well as general relativity effects like Lense-Thirring and De Sitter, will help scientific advancements in Theoretical Physics, Geophysics, and Geodesy, among other scientific fields.

gr-qc↗

arXiv2022

Gravitomagnetic induction in the field of a gravitational wave

The interaction of a plane gravitational wave with test masses can be described in the proper detector frame, using Fermi coordinates, in terms of a gravitoelectric and a gravitomagnetic field. We use this approach to calculate the displacements produced by gravitational waves up to second order in the distance parameter and, in doing so, we emphasize the relevance of the gravitomagnetic contribution related to gravitational induction. In addition, we show how this approach can be generalized to calculate displacements up to arbitrary order.

gr-qc↗