Carla Rodrigues Almeida

University of São Paulo | USP

Historicamente, as primeiras soluções da relatividade geral não foram reconhecidas como soluções de buracos negros. Elas foram, a princípio, idealizadas para descrever o campo gravitacional de objetos massivos esfericamente simétricos, como o Sol ou o elétron. Neste artigo, vamos apresentar as soluções de buracos negros em seu contexto histórico e...

Quantum gravity is effective in domains where both quantum effects and gravity are essential, such as in the vicinity of space-time singularities. This paper will investigate the quantization of a black-hole gravity, particularly the region surrounding the singularity at the origin of the coordinate system. Describing the system with a Hamiltonian...

Reasoning by analogies permeates theoretical developments in physics and astrophysics, motivated by the unreachable nature of many phenomena at play. For example, analogies have been used to understand black hole physics, leading to the development of a thermodynamic theory for these objects and the discovery of the Hawking effect. The latter, whic...

The first edition of the event As Astrocientistas: the Brazilian Meeting of Women and Girls in Astrophysics, Cosmology, and Gravitation, happened in February 2021. It gathered great names of Brazilian science to pay homage to Brazilian female researchers and other female physicists with close ties to our community. This paper presents our motivatio...

Em fevereiro de 2021 ocorreu a primeira edição do evento As Astrocientistas: Encontro Brasileiro de Meninas e Mulheres da Astrofísica, Cosmologia e Gravitação, que reuniu grandes nomes da ciência brasileira para homenagear as pesquisadoras brasileiras ou estrangeiras que tenham vínculos com o nosso país, em celebração ao dia internacional das mulhe...

In 1969, Roger Penrose proposed a mechanism to extract rotational energy from a Kerr black hole. With this, he inspired two lines of investigation in the years after. On the one side, the Penrose process, as it became known, allowed a comparison between black-hole mechanics and thermodynamics. On the other, it opened a path to a quantum description...

Quantum gravity is effective in domains where both quantum effects and gravity are important, such as in the vicinity of space-time singularities. This paper will investigate the quantization of a black-hole gravity, particularly the region surrounding the singularity hidden inside the event horizon. Describing the system with a Hamiltonian formali...

In this paper, we discuss classical and quantum aspects of cosmological models in the Brans–Dicke theory. First, we review cosmological bounce solutions in the Brans–Dicke theory that obeys energy conditions (without ghost) for a universe filled with radiative fluid. Then, we quantize this classical model in a canonical way, establishing the corres...

In this paper we discuss classical and quantum aspects of cosmological models in Brans-Dicke theory. First, we review cosmological bounce solution in Brans-Dicke theory that obeys energy conditions (without ghost) for a universe filled with radiative fluid. Then we quantize this classical model in a canonical way, establishing the corresponding Whe...

A existência de buracos negros é uma das consequências mais contraintuitivas da teoria da relatividade geral de Einstein. A descoberta destes enigmáticos objetos não aconteceu em uma data específica, nem por uma pessoa em particular. O desenvolvimento teórico do conceito moderno de buracos negros se estende por um período de mais de cem anos de est...

Resumo Buracos negros são provavelmente a mais estranha consequência da relatividade geral. Eles são objetos super densos envolvidos por uma membrana unidirecional que escondem uma singularidade em seu interior e aprisionam qualquer matéria que se arrisca a adentrá-lo, incluindo a luz. A história da descoberta desses corpos enigmáticos se inicia co...

The idea of gravitational collapse can be traced back to the first solution of Einstein’s equations, but in these early stages, compelling evidence to support this idea was lacking. Furthermore, there were many theoretical gaps underlying the conviction that a star could not contract beyond its critical radius. The philosophical views of the early...

The idea of gravitational collapse can be traced back to the first solution of Einstein's equations, but in these early stages, compelling evidence to support this idea was lacking. Furthermore, there were many theoretical gaps underlying the conviction that a star could not contract beyond its critical radius. The philosophical views of the early...

In this work, we present a complete analysis of the quantization of the classical Brans-Dicke theory using the method of affine quantization in the Hamiltonian description of the theory. The affine quantization method is based on the symmetry of the phase space of the system, in this case the (positive) half-plane, which is identified with the affi...

In this work, we present a complete analysis of the quantisation of the classical Brans-Dicke Theory using the method of affine quantisation in the Hamiltonian description of the theory. The affine quantisation method is based on the symmetry of the phase-space of the system, in this case the (positive) half-plane, that is identified with the affin...

Um estudo dos aspectos matemáticos e físicos da quantização da Teoria Clássica de Brans-Dicke usando os métodos canônicos e afim.

The Hamiltonian of any quantum cosmological model must obey some conditions in order to be self-adjoint, or to admit self-adjoint extensions. We will consider in this paper the self-adjoint character of the Hamiltonian resulting from the Brans-Dicke theory, both in Einstein and Jordan frames. In both cases we find the wave-function solutions in ord...

This article is an introductory presentation of the quantization of the half-plane based on affine coherent states (ACS). The half-plane is viewed as the phase space for the dynamics of a positive physical quantity evolving with time, and its affine symmetry is preserved due to the covariance of this type of quantization. We promote the interest of...

In this paper, the problem of the self-adjointness for the case of a quantum minisuperspace Hamiltonian retrieved from a Brans-Dicke (BD) action is investigated. Our matter content is presented in terms of a perfect fluid, onto which the Schutz's formalism will be applied. We use the von Neumann theorem and the similarity with the Laplacian operato...

The Brans-Dicke action is one of the most natural extensions of the Einstein-Hilbert action. It is based on the introduction of a fundamental scalar field that effectively incorporates a dynamics to the gravitational coupling $G$. In spite of the diverse motivations and the rich phenomenology that comes from its solutions, Solar System tests impose...

We discuss the issue of unitarity in particular quantum cosmological models with scalar field. The time variable is recovered, in this context, by using the Schutz's formalism for a radiative fluid. Two cases are considered: a phantom scalar field and an ordinary scalar field. For the first case, it is shown that the evolution is unitary provided a...