Gödel-type solutions in $$f(R,T,R_{\mu \nu } T^{\mu \nu }$$) gravity

Abstract

In this paper, $$f(R,T,R_{\mu \nu } T^{\mu \nu }$$ f ( R , T , R μ ν T μ ν ) gravity is considered. It is a modified theory of gravity that exhibits a strong coupling of gravitational and matter fields. Therefore, if gravity is governed by this model a number of issues must be re-examined. In this context, the question of causality and its violation is studied. Such analysis is carried out using the Gödel-type solutions. It is shown that this model allows both causal and non-causal solutions. These solutions depend directly on the content of matter present in the universe. For the non-causal solution, a critical radius is calculated, beyond which causality is violated. Taking different matter contents, an infinite critical radius emerges that leads to a causal solution. In this causal solution, a natural relationship emerges between the parameters that determine the matter considered.

Physical aspects of modified gravity theories

“…where a new generic function is added to the part [32]. This function is further based on specific contractions between the Einstein tensor and energy-momentum tensor [80]:…”

“…Based on a theoretical perspective, this type of an approach is viable and can lead to different effects [70−79]. Hence, the extension towards an invariant based on the interplay between the Einstein tensor and energy-momentum tensor occurs naturally [80] and can lead to a viable modified gravity theory.…”

“…In a recent study [80], the authors investigated the possible interplay between the Einstein tensor and matter energy-momentum tensor, embedding also specific derivative couplings. By considering a linear model in the proposed action, the perturbation analysis showed the viability of this type of a cosmological model.…”

“We Go through a Bit of Everything”: The labyrinth career of the professional trajectories of executive women

“…Several studies analyze the issue of gender in organizations. However, they focus on the differences between men and women to explain organizational results, such as in those of Gonçalves et al (2019), Huang and Kisgen (2013), Amore and Garofalo (2016), Berger et al (2014), Frye and Pham (2018), Grant and Taylor (2014), and Liu et al (2014). This focus reinforces the male figure as the ideal worker, suggesting that women should adapt to the characteristics of the former, which are considered more efficient in the organizational environment.…”

“…Gender stereotypes are exposed as one of the main barriers to the professional growth of women in organizations (Gonçalves et al, 2019;Nunes & Casaca, 2015;Mota et al, 2014;Vieira et al, 2019). The naturalization of these stereotypes harms both women and men, but a hierarchy of privilege must be considered that orders these guidelines, above all, in the work environment.…”