Scalar–Tensor–Vector Modified Gravity in Light of the Planck 2018 Data

The recent data release by the Planck satellite collaboration presents a renewed challenge for modified theories of gravitation. Such theories must be capable of reproducing the observed angular power spectrum of the cosmic microwave background radiation. For modified theories of gravity, an added challenge lies in the fact that standard computational tools do not readily accommodate the features of a theory with a variable gravitational coupling coefficient. An alternative is to use less accurate but more easily modifiable semianalytical approximations to reproduce at least the qualitative features of the angular power spectrum. We extend a calculation that was used previously to demonstrate compatibility between the Scalar–Tensor–Vector–Gravity (STVG) theory, also known by the acronym MOG, and data from the Wilkinson Microwave Anisotropy Probe (WMAP) to show the consistency between the theory and the newly released Planck 2018 data. We find that within the limits of this approximation, the theory accurately reproduces the features of the angular power spectrum.

THE LAWS OF MOTION IN GAUGE THEORIES OF GRAVITY

The general theory of relativity (GR) states that the matter that generates the gravitational field cannot move arbitrarily, it must obey certain equations that follow from the equations of the gravitational field as conditions for their compatibility. In this article we analyze the laws of motion of charged matter in gauge theories of gravitation with higher derivatives of field variables. Object: to consider the laws of motion in gauge theories of gravitation. Task to analyze the laws of motion of charged matter in gauge theories of gravitation with higher derivatives of field variables. Conclusions: it is proved that the equation of an arbitrary gauge field of internal symmetry regardless of the specific type of its Lagrangian can be written both in the form of Einstein's equation and in superpotential form, i.e. as an expression of the total current of gauge charges through the superpotential determined by a specific type of Lagrangian that is, in the form of the Young-Mills equations. So this is a consequence of purely-symmetry theory. Also, a statement is proved in which the constraints on the equations of some fields, which follow from the assumption of the equations of motion for other fields. Research perspectives: nowadays, scientists register gravitational waves and analyze the conditions for their emission, and interest in the problem of motion has been renewed. Note that theories of gravity with higher derivatives of field variables in the Lagrangian of the gravitational field (for example, f(R)-theories) have become very popular in the present. Note that on the basis of the laws of motion of charged matter considered in the article in the gauge theory of gravity, it is possible to successfully further investigate the laws of motion in other theories of gravity, which can be useful in various areas of theoretical and experimental physics.

Testing Gravitational Theories in the Field of the Earth with the SaToR-G Experiment

A new satellite-based experiment in the field of gravitation, SaToR-G, is presented. It aims to compare the predictions of different theories of gravitation in the limit of weak-field and slow-motion. The ultimate goal of SaToR-G is searching for possible “new physics” beyond General Relativity, which represent the state-of-the-art of our current knowledge of gravitational physics. A key role in the above perspective is the theoretical and experimental framework that confines our work. To this end, we will exploit as much as possible the classical framework suggested by R.H. Dicke over fifty years ago.

The Solution to Graviton as Goldstone Boson

The study of Graviton as Goldstone bosons appeared in the 1960s, after Bjorken interacting idea of Electrodynamics. However, no recent advancement has been done in the field, because of very constraints as well as low-attractiveness of the theory. We do the non-metric tensor (covariant derivative of the metric tensor) case of Gravitation and eventually get SO(1,3) broken in the vacuum state of quantized field theory, then find the Graviton as Goldstone Boson. We, in final, see that Gravitons can have appearances in many modified (and extended) theories of Gravitation.

Einstein’s General Theory of Relativity and the Development of Modified Theories of Gravitation

We briefly review both Einstein’s general theory of relativity and the development of modified theories of gravitation with theoretical and observational motivations. For this, we discuss the theoretical properties and weaknesses of general relativity. We also mention attempts that have been made to develop the theory of quantum gravity. The recent detections of a gravitational wave, dark matter, and dark energy have opened new windows into astrophysics, as well as cosmology, through which tests to determine the theory of gravitation that best describes our Universe would be interesting. Most of all, note that we cannot clearly describe our Universe, including dark matter and dark energy, with standard particle models and the general theory of relativity. In these respects, we must be open-minded and study all possible aspects.

The Non-Metric Solution to Graviton as Goldstone Boson

The study of Graviton as Goldstone bosons appeared in the 1960s, after Bjorken interacting idea of Electrodynamics. However, no recent advancement has been done in the field, because of very constraints as well as low-attractiveness of the theory. We do the non-metric tensor (covariant derivative of the metric tensor) case of Gravitation and eventually get SO(1,3) broken in the vacuum state of quantized field theory, then find the Graviton as Goldstone Boson. We, in final, see that Gravitons can have appearances in many modified (and extended) theories of Gravitation.

Scalar Tensor Theories of Gravitation in Ruban’s Space Time

In this paper, we have studied the field equation in the context of cosmic string source in the scalar-tensor theories of gravitation given by Brans and Dicke and Saez-Ballester with the aid of Ruban’s Space time. Exact cosmological models in both the theories are presented with the help of special law of variation suggested by Berman (1983) and relation between metric coefficient nnRxQ=. Finally, some physical and kinematical properties of the model are carried out.