A revista Cadernos de Astronomia é uma publicação semestral do Núcleo Cosmo-Ufes da Universidade Federal do Espírito Santo e que conta também com recursos humanos do Centro Brasileiro de Pesquisas Físicas e da Universidade Federal de Ouro Preto (vide o Corpo Editorial). Propõe-se a publicar artigos destinados à divulgação científica, história da ciência, ensino e pesquisa em astronomia e áreas correlatas. O objetivo é tornar acessível a um amplo público, que inclui estudantes secundários, graduandos e simpatizantes da área, o conhecimento científico relacionado à astronomia, cosmologia e gravitação. Possuindo acesso totalmente gratuito, cada número dedica uma seção inteira a um tema específico, onde especialistas nacionais e internacionais discutem em detalhes aspectos qualitativos e quantitativos do tópico em questão. A partir de 2023 os números semestrais dos CdA serão publicados nos meses de Março e Setembro. Cada um desses números possuem datas limite para receber submissões: Números publicados em Março - Submissões feitas até 10 de Janeiro; Números publicados em Setembro - Submissões feitas até 1º de Julho. Submissões recebidas após as datas limite acima não terão garantias de que, uma vez aceitas para publicação, façam parte do próximo número. Não sendo publicadas no próximo número, elas são automaticamente programadas para publicação no número subsequente a ser lançado.
It includes the editorial information for this edition, the Letter to the Reader, and the Table of Contents.
Copyright (c) 2026 Os Editores https://creativecommons.org/licenses/by/4.0
Dark energy and the challenges to the standard cosmological model
Observational evidence that the Universe is undergoing accelerated expansion represents one of the main challenges of modern cosmology, usually attributed to the presence of a dominant component known as dark energy. The standard cosmological model, ΛCDM, provides a consistent description of a wide range of observations, but faces significant difficulties from both a theoretical and observational standpoint. In this article, we present a review of the ΛCDM model, discussing its theoretical foundation and the main observational tests that support its validity. We emphasize recent observational strains, such as those associated with the Hubble constant (H0) and the amplitude of matter fluctuations (S8), as well as recent results from the DESI survey that suggest possible deviations from the standard model. We also discuss the implications of these strains and possible extensions of the model, highlighting the role of scenarios with dynamic dark energy. This overview seeks to provide an updated view of the challenges faced by contemporary cosmology and the prospects for understanding cosmic acceleration.
Copyright (c) 2026 Rodrigo Von Marttens, Jailson Alcaniz, Saulo Carneiro https://creativecommons.org/licenses/by/4.0
Cosmological considerations on the general theory of relativity.
We present the translation of the article published by Albert Einstein in 1917. In it, he introduces, for the first time, a cosmological constant, a term that today plays a very important role in the standard model of cosmology. Some introductory comments are presented, followed by the Portuguese version of the text originally written in German.
Copyright (c) 2026 Albert Einstein; Júlio C. Fabris (trad.), Oliver F. Piattella (trad.) https://creativecommons.org/licenses/by/4.0
Astroparticle physics plays a central role in addressing fundamental questions in modern physics by connecting particle physics, cosmology, and astrophysics. Among the main problems, we highlight the nature of dark matter and dark energy, primordial inflation, the matter-antimatter asymmetry of the universe, and the origin of ultra-high-energy cosmic messengers. In this article, we review the main observational evidence for dark matter, which spans scales from galactic to cosmological, and discuss the two most explored scenarios for its nature: primordial black holes and new fundamental particles beyond the Standard Model. We explore the main theoretical and experimental bottlenecks that challenge the search for the nature of dark matter, highlighting those associated with extended mass distributions of primordial black holes and the absence of weakly interacting massive particle signals in direct, indirect, and accelerator detection experiments. We also discuss the role of next-generation experiments, including very high-energy gamma-ray telescopes and multi-messenger detectors. Finally, we conclude that the combination of high-precision observations and theoretical advances will be crucial to elucidating the microphysics of dark matter and deepening our understanding of the extreme universe.
Copyright (c) 2026 Clarissa Siqueira https://creativecommons.org/licenses/by/4.0
Massive neutrinos in cosmology: geometry and growth of structures
Neutrinos are the most abundant particles in the Universe after photons, yet their masses remain unknown. In this article we show how modern cosmology provides a powerful way to investigate this fundamental property through the Cosmic Microwave Background, baryon acoustic oscillations, and the growth of large-scale structure. We discuss how neutrinos, relativistic in the early Universe and non-relativistic at late times, leave imprints both on the expansion history and on the formation of the cosmic web. We also show how recent galaxy survey data, such as DESI, combined with cosmological simulations, allow increasingly precise constraints on the sum of neutrino masses, turning the Universe into a powerful detector of these particles.
Copyright (c) 2026 Guilherme Brando https://creativecommons.org/licenses/by/4.0
Many worlds interpretation of quantum mechanics? - It is simple!
We describe in a relatively popular way the main ideas of the many-worlds interpretation of quantum mechanics. We discuss the question about its “counter-intuitiveness” citing some literature works written before and after its invention.
Divulgação Científica, Ciência e Sociedade
Copyright (c) 2026 Alexander Yu. Kamenshchik https://creativecommons.org/licenses/by/4.0
Kepler's laws: inferring the mass of Sagittarius A*
This article aims to present an investigative approach to the study of black holes in light of Newtonian Mechanics, with a mathematical formulation developed by a high school student. The proposal involves the use of fundamental concepts such as Newton's Laws, Kepler's Laws, and the Law of Universal Gravitation. The study begins with a historical and theoretical contextualization, followed by a brief discussion of the scientific confirmation of the existence of black holes, highlighting the case of Sagittarius A*, a supermassive object located at the center of the Milky Way. Through orbital analysis of stars near this object, based on literature data, and using Kepler's Third Law, its mass was estimated. The data were processed using a spreadsheet, allowing for statistical analysis. The comparison between the obtained results, namely (4.46 ± 0.01) × 10⁶ M⊙, and those found in the literature showed an uncertainty of ≈ 4%. Thus, the potential of classical mechanics as an introductory tool in teaching advanced concepts in astronomy becomes evident.
Copyright (c) 2026 Mateus Barbosa Ferreira, Adriano Mesquita Oliveira https://creativecommons.org/licenses/by/4.0
Challenges in the search for gravitational wave signals
This paper presents the challenges faced in the search for gravitational-wave signals by the LIGO detectors, arising from the presence of noise in the data. Such noise can couple to the interferometers through different physical mechanisms associated with the environment or the instrumentation. As a consequence, it can affect the parameter estimation of real detections, reduce the statistical significance of observed events, or, in some cases, mimic astrophysical signals.
Copyright (c) 2026 Tábata Aira Ferreira https://creativecommons.org/licenses/by/4.0
Photometry and calibration of Type Ia supernovae
Type Ia supernovae provided the first evidence, by the end of the 1990's, that the expansion of the Universe is accelerated. Since then, various groups, using different observations have been confirmed this pioneer result, indicating that the Universe is in phase dominated by a cosmological constant, which is the simplest mechanism to explain the cosmic acceleration, in the context of general relativity. However, as the observation techniques were improving, the number of observed events increased to a point at the statistical uncertainties are not the biggest problem. The main focus of new projects shifted to controlling systematic errors due to modeling of the phenomenon, observation conditions e equipment limitations. In this work, we present a small glimpse of the photometry challenge, regarding the observation of astronomical events em large wavelenght bands and, from this information, infer intrinsic properties of such events. In addition, in briefly consider the challenge of controlling the propagation of uncertainties to the estimated distances e, consequently, to the cosmological parameters obtained from them.
Copyright (c) 2026 Ribamar R. R. Reis, Beatriz B. Siffert https://creativecommons.org/licenses/by/4.0
Cosmological tensions in H0 and S8: current overview
The standard cosmological model has provided, for several decades, a consistent description of a wide range of cosmological and astrophysical observations. Despite this success, persistent discrepancies in the determination of fundamental parameters, in particular the Hubble constant (H0) and the amplitude of structure growth, commonly parametrized by S8, reveal significant tensions between probes of the early and late universe, with varying levels of statistical significance. These tensions may be partially associated with systematic uncertainties that are not yet fully understood, but they also motivate the investigation of extensions of ΛCDM, including modifications to dark energy, the dark sector, and gravity on large scales. In this didactic review, we present an overview of the main observations currently involved in these discrepancies, discuss their potential observational biases, and synthesize the most relevant theoretical scenarios, highlighting the prospects offered by current-generation cosmological surveys.
Copyright (c) 2026 Emanuelly Silva, Miguel Sabogal, Rafael Nunes https://creativecommons.org/licenses/by/4.0
Earth's and Mars' atmospheres: an astrobiological approach
This article compares the atmospheres of Earth and Mars from an astrobiological perspective, examining their evolution, composition, and the processes that determine habitability. For Earth, it discusses formation and climate regulation by the oceans and the sequestration of CO2 through sedimentation, the rise of an O2-rich atmosphere (the Great Oxidation Event, GOE), and the roles of N2, O2, and O3 in maintaining liquid water and supporting life. For Mars, it analyzes the current low-pressure, CO2-dominated atmosphere, atmospheric and water loss, the intensity of surface radiation, and the soil’s oxidizing chemistry that compromise the preservation of organic matter. The text emphasizes the complementarity between atmospheric studies and subsurface investigations, identifying subsurface refugia, with lower radiation doses and reduced chemical oxidation, as the most promising locations for biosignature preservation. The article adopts a didactic, integrative approach intended to help students and enthusiasts in astronomy and astrobiology understand the key processes that govern planetary habitability.
Copyright (c) 2026 Gustavo Santos Rodrigues, Anthony Henrique Perucci Mostaro https://creativecommons.org/licenses/by/4.0
Editorial information of the 6th volume, issue 2, from Cadernos de Astronomia (2025). Copyright page, Letter to Readers and Table of Contents.
Copyright (c) 2025 Os Editores https://creativecommons.org/licenses/by/4.0
Niède Guidon, Serra da Capivara and celestial records in rock art: science, culture and archaeoastronomy in the Piauí caatinga
This article explores the trajectory of archaeologist Niède Guidon and her scientific-cultural legacy based on her discoveries in Serra da Capivara, Piauí. Based on her contribution to Brazilian archaeology and the importance of Serra da Capivara National Park as a world heritage site, we discuss the role of science and education in preserving historical memory and valuing indigenous cultures. Finally, we analyze the archaeoastronomical potential of the region's rock paintings, exploring the possible relationship between prehistoric graphic records and celestial observations of its ancient inhabitants. The analysis adopts an interdisciplinary perspective, integrating archaeology, cultural astronomy and history of science.
Copyright (c) 2025 Viviana Borges Corte, Rizalva dos Santos Cardoso Rabelo https://creativecommons.org/licenses/by/4.0
<pre id="tw-target-text" class="tw-data-text tw-text-large tw-ta" dir="ltr" tabindex="-1" role="text" data-placeholder="Tradução" data-ved="2ahUKEwiM24zG16uQAxU6rJUCHVvwJVoQ3ewLegQIDBAV" aria-label="Texto traduzido: Brief comments by Brazilian physicists Ulysses Câmara da Silva (Federal University of Espírito Santo), Nelson Pinto Neto (Brazilian Center for Physics Research), and Olival Freire (Federal University of Bahia) on the 2025 Nobel Prize in Physics, which highlights work demonstrating quantum properties in non-microscopic systems.">Brief comments by Brazilian physicists Ulysses Câmara da Silva (Federal University of Espírito Santo), Nelson Pinto Neto (Brazilian Center for Physics Research), and Olival Freire (Federal University of Bahia) on the 2025 Nobel Prize in Physics, which highlights work demonstrating quantum properties in non-microscopic systems.
Copyright (c) 2025 Júlio C. Fabris https://creativecommons.org/licenses/by/4.0
Explanatory note about the so-called little red dots (LRDs), observed by the James Webb Telescope. These compact, high-mass objects would have formed at a time when the universe was still quite young, which raises questions within the scientific community, since there wouldn't be enough time for objects with such pronounced reddish brightness, characteristic of old galaxies, to form.
Copyright (c) 2025 Stéfani Faller https://creativecommons.org/licenses/by/4.0
Commented translation of Heisenberg's paper, “On the reinterpretation of kinematic and mechanical relations in quantum theory”
We present the translation of the article published by Werner Heisenberg in 1925, which constitutes a landmark in the development of quantum mechanics. Some introductory comments are presented, followed by the Portuguese version of the text originally written in German.
Copyright (c) 2025 Júlio C. Fabris, Oliver F. Piattella https://creativecommons.org/licenses/by/4.0
The mathematical symphony of the quantum world
This text explores the profound and beautiful interplay between quantum physics and mathematics. We jour ney from the crisis of classical physics at the turn of the 20th century to the elegant, abstract mathematical frameworks that define modern quantum mechanics. We will see how physical problems forced the invention of new mathematics and how mathematical structures, in turn, provided the language to describe the quantum realm. Key figures like Planck, Einstein, Heisenberg, Born, von Neumann, Weyl, and Dirac will guide us,revealing a story where physical intuition and mathematical formalism are inextricably linked.
Copyright (c) 2025 Giuseppe Dito https://creativecommons.org/licenses/by/4.0
Formation and evolution of large-scale structures from the perspective of halo models
The current era of large-scale structure research, driven by projects such as DESI, Euclid, and LSST, demands efficient methods for modeling and interpreting vast datasets. The matter power spectrum, P(k, z), is a central statistical estimator in these efforts, but its modeling on nonlinear scales remains an ongoing challenge in the literature. In this context, halo models provide a powerful approach by associating the distribution of matter with halos of different masses. Widely used in tools such as HALOFIT and HM-CODE, these models play a fundamental role in data analysis and cosmological parameter inference. This article aims to provide an introductory and didactic resource that reviews the essential components of halo models, highlighting their advantages, such as flexibility beyond the standard ΛCDM model, and their impact on galaxy property predictions, observational studies, and theoretical modeling. The review is presented in a clear and accessible manner, aiming to introduce this approach, which will become increasingly indispensable in modern cosmology.
Copyright (c) 2025 Emanuelly Silva, Rafael C. Nunes https://creativecommons.org/licenses/by/4.0
Quantum mechanics was developed in the early 20th century as a computational algorithm to organize and predict the strange results of a wide variety of experiments involving the microscopic world (molecules, atoms, elementary particles), which appeared random but had a predictable probabilistic distribution. Despite its overwhelming success, the conceptual foundations of this algorithm remain unclear and extremely controversial. How can we connect the microscopic world described by quantum mechanics with the macroscopic world of our daily experience? What is the role of observers in this connection? Why don't strange quantum phenomena occur on macroscopic scales? How can we explain the nonlocal nature of quantum phenomena? In this article I will present some attempts to answer these and other basic questions, which constitute different theories with completely different worldviews, commenting on their strengths and weaknesses. We will conclude that quantum theory is still under construction, as there is no consensual formulation. Its development is a fundamental problem in contemporary physics, and in thought in general.
Copyright (c) 2025 Nelson Pinto Neto https://creativecommons.org/licenses/by/4.0
Telescopes: history and applications in astronomy
<div id="tw-container" class="nev7se" data-cp="1" data-nnttsvi="1" data-sletp="false" data-sm="1" data-ssbp="false" data-sugg-time="500" data-sugg-url="https://clients1.google.com/complete/search" data-uilc="pt-BR" data-vil=",af,af-ZA,am,am-ET,ar-EG,ar-AE,ar-KW,ar-QA,ar,ar-IL,ar-JO,ar-LB,ar-PS,az,az-AZ,bg,bg-BG,bn,bn-BD,bn-IN,ca,ca-es,cs,cs-CZ,de,de-DE,de-CH,de-AT,de-LI,en,en-US,en-CA,en-AU,en-NZ,en-GB,en-IN,en-KE,en-TZ,en-NG,en-GH,en-PH,en-ZA,es,es-ES,es-AR,es-UY,es-419,es-BO,es-CL,es-CR,es-CO,es-DO,es-EC,es-GT,es-HN,es-NI,es-PA,es-PE,es-PR,es-PY,es-SV,es-VE,es-MX,es-US,eu,eu-ES,fi,fi-FI,fr,fr-FR,fr-CH,fr-BE,gl,gl-ES,gu,gu-IN,he,he-IL,iw,iw-IL,hu,hu-HU,hy,hy-AM,id,id-ID,is,is-IS,it,it-IT,it-CH,ja,ja-JP,jv,jv-ID,ka,ka-GE,km,km-KH,kn,kn-IN,ko,ko-KR,la,lo,lo-LA,lv,lv-LV,ml,ml-IN,mr,mr-IN,ms,ms-MY,nl,nl-NL,nb,nb-NO,ne,ne-NP,pl,pl-PL,pt,pt-BR,pt-PT,ro,ro-RO,ru,ru-RU,si-LK,sk,sk-SK,sr,sr-RS,su,su-ID,sv,sv-SE,sw,sw-TZ,sw-KE,ta,ta-IN,ta-SG,ta-LK,ta-MY,te,te-IN,tr,tr-TR,ur,ur-PK,ur-IN,yue,yue-HK,yue-Hant-HK,zh-HK,zh,zh-CN,zh-cmn,zh-cmn-CN,zh-Hans,zh-Hans-CN,zh-cmn-Hans,zh-cmn-Hans-CN,cmn-CN,cmn-Hans,cmn-Hans-CN,zh-TW,zh-Hant-TW,cmn-TW,cmn-Hant-TW,zh-cmn-TW,zh-cmn-Hant-TW,zu,zu-ZA,hi,hi-IN,tl,tl-PH,pa,pa-IN"> <pre id="tw-target-text" class="tw-data-text tw-text-large tw-ta" dir="ltr" tabindex="-1" role="text" data-placeholder="Tradução" data-ved="2ahUKEwj32f3Sw8CTAxVmg5UCHX0RE2cQ3ewLegQIDBAW" aria-label="Texto traduzido: This article presents an account of an experience carried out in a municipal elementary school in Linhares-ES, with some 9th-grade students. The reflection stems from the participation of the E.M.E.F. “Prefeito Roberto Calmon” school in the Espírito Santo Astronomy Exhibition. With the aim of advancing astronomy studies in the school context, we present a comprehensive research project on the topic: Telescopes, from their beginnings to the present day. Our research sought information about the equipment, personalities, and contributions to astronomy. The topic was presented to the students of the aforementioned school and other schools in the city of Linhares-ES, providing us with an enriching learning experience. During the VII Espírito Santo Astronomy Exhibition, a collaborative competition, we received wonderful contributions that greatly enhanced our scientific outreach work, and we emphasize the importance of disseminating this information also through a website created by the students and through the publication of this manuscript.">This article presents an account of an experience carried out in a municipal elementary school in Linhares-ES, with some 9th-grade students. The reflection stems from the participation of the E.M.E.F. “Prefeito Roberto Calmon” school in the Espírito Santo Astronomy Exhibition. With the aim of advancing astronomy studies in the school context, we present a comprehensive research project on the topic: Telescopes, from their beginnings to the present day. Our research sought information about the equipment, personalities, and contributions to astronomy. The topic was presented to the students of the aforementioned school and other schools in the city of Linhares-ES, providing us with an enriching learning experience. During the VII Espírito Santo Astronomy Exhibition, a collaborative competition, we received wonderful contributions that greatly enhanced our scientific outreach work, and we emphasize the importance of disseminating this information also through a website created by the students and through the publication of this manuscript.
Copyright (c) 2026 Alexsandra de Souza Batista , Francisco Soares dos Anjos Neto, Ray Rodrigues Oliveira Borges , Ruan Silva De Sá, Roger da Trindade Gomes https://creativecommons.org/licenses/by/4.0
White dwarfs are highly compact stellar remnants resulting from the evolutionary process of stars with masses up to ten times that of our Sun. Their core is composed predominantly of electronically degenerate matter. In an ordinary star, there is a balance between the intrinsic gravitational attraction and the internal pressure generated by the heat and nuclear radiation from its core. In a white dwarf, collapse is prevented by the electron degeneracy pressure, a quantum effect that arises from the statistical properties of fermions through the Pauli exclusion principle. In this article, we present a simple theoretical model for the structure of white dwarfs and discuss some of its applications in astrophysics.
Copyright (c) 2025 Marco Moriconi, Rodrigo Negreiros https://creativecommons.org/licenses/by/4.0
Density functional theory: foundations, challenges, and new horizons in the quantum mechanics of atoms, molecules, and solids
On the centennial of quantum mechanics, this work provides a comprehensive review of the theoretical foundations, current challenges, and emerging frontiers in many-body quantum theory, with particular emphasis on Density Functional Theory (DFT), the GW approximation, and their applications in fields such as astronomy and in novel methodologies grounded in Machine Learning (ML) and evolutionary algorithms. By surveying these diverse applications, from astrophysical systems to artificial intelligence, we underscore the inherently interdisciplinary character of this sixty-year-old framework, which continues to be indispensable for advancing our understanding of the properties of matter and for driving technological innovation.
Copyright (c) 2025 Matheus S. Barbosa, Leonardo Villegas-Lelovsky, Alberto Torres , Alan B. de Oliveira, Amaury de Melo Souza, Breno R. L. Galvao, Alexandre R. Rocha, Mário S. C. Mazzoni, Matheus J. S. Matos https://creativecommons.org/licenses/by/4.0
Revisiting Duhem: quasars, cosmology, and the tripartite relationship between theories and experiments.
This essay examines the work of the physicist and philosopher of science Pierre Duhem, whose contributions anticipated by more than fifty years several elements later developed in the epistemologies of Popper, Kuhn, and Lakatos. Duhem argued that scientific progress cannot be adequately described as a simple confrontation between theory and experiment. Instead, it involves a tripartite relationship in which competing theories are compared in light of experimental results, with experiments functioning mainly as a basis for comparison and theory choice. To illustrate Duhem’s theses, we discuss the early detections of quasars and their role in the cosmological debate between the Big Bang and the Steady State theories. The observed variation in the number of quasars over cosmic time indicated that the Universe is a dynamically evolving physical system, a feature predicted by the Big Bang theory but not explained within the Steady State model.
Copyright (c) 2026 Danilo Rodrigues, Jose Raymundo Novaes Chiappin, Ramachrisna Teixeira, Jojomar Lucena da Silva https://creativecommons.org/licenses/by/4.0
Quantum effects in curved spaces: from the particle concept to field theory
Quantum field theory is currently the most accurate description of matter, but this framework is the result of a long evolution of the concept of particle in physics. In this article, we trace this development: starting from classical mechanics, where particles are treated as point-like objects; moving to quantum mechanics, where they are described as waves associated with probabilities; and finally arriving at quantum field theory, where particles appear as excitations of fundamental fields. We show that in curved or expanding spacetimes, the definition of a particle is no longer unique: different observers can adopt different vacuum states and consequently identify particles in different ways. We also discuss the role of the quantum vacuum and its connection to the cosmological constant problem, one of the major open questions in contemporary physics. By connecting quantum theory, general relativity, and cosmology, the article addresses both the progress achieved and the conceptual challenges that remain in describing the universe at its most extreme scales.
Copyright (c) 2025 Sandro Dias Pinto Vitenti https://creativecommons.org/licenses/by/4.0
The problem of time in gravitation and cosmology
IIn this outreach review, we discuss key concepts of quantum theory and their application to the construction of a quantum theory of gravitation and cosmology. Of special significance is the problem of time: how can we understand the evolution of a quantum Universe if there is no classical variable that represents an absolute time?
Copyright (c) 2025 Leonardo Chataignier https://creativecommons.org/licenses/by/4.0
Tests of quantum gravity in the laboratory
This work introduces some of the main topics related to recent efforts to conduct experiments that prove the quantum nature of gravity in the laboratory. An overview of the conceptual problems involved will be presented, describing the most well-known theories as well as discussing some of the most relevant approaches for laboratory experiments, such as the Diósi-Penrose decoherence model. Using the formalism of canonical quantization of linearized gravity, it is demonstrated how predictions are beginning to be extracted from the known theories for a regime that is still little explored experimentally. Next, some of the main experimental proposals in the literature are discussed, particularly the possibility of generating entanglement between two massive sources in a state of quantum superposition and the tests involving optomechanical systems. The conclusions list open problems related to traditional methods of gravity quantization in the low-energy regime and discuss the most promising experimental paths to test predictions that could confirm the quantum nature of the gravitational field.
Copyright (c) 2025 Francisco Bento Lustosa https://creativecommons.org/licenses/by/4.0
In 1974, a discovery shook the scientific community. Stephen Hawking showed that, when quantum mechanics is taken into account, black holes are not black but emit thermal radiation, as measured by stationary observers far away from the black hole. Since then, the resulting process of black hole evaporation has sparked a debate that divides physicists to this day: what happens to the information that falls into the black hole? In this article, we will review the process of black hole evaporation, showing in particular that there is nothing paradoxical about the loss of information in the end. We will then examine the alternatives to information loss, highlighting their pros and cons.
Copyright (c) 2025 André G. S. Landulfo https://creativecommons.org/licenses/by/4.0
Quantum effects in gravitation and gravitational analogues
Modern physics reveals that the quantum vacuum, far from being an absolutely empty space, exhibits peculiar properties when analyzed in a curved spacetime, such as in the vicinity of black holes. The interaction between quantum fields and spacetime geometry is formally described by Quantum Field Theory in Curved Spacetimes, which treats gravitational effects as classical manifestations of spacetime curvature, as established by General Relativity. Hawking radiation, for instance, describes how quantum fluctuations near a black hole lead to thermal emission to the exterior, resulting in its gradual evaporation. Another example is the Unruh effect, which predicts that an accelerated observer perceives a thermal bath of radiation in a region where an inertial observer would see only the particle vacuum. However, these phenomena are difficult to detect directly due to the extreme scales involved, which result in thermal emissions of extremely low temperatures. To overcome this limitation, scientists have developed analogue models of gravity. These analogue models are systems (for example, fluid flows and ultracold gases) that reproduce, in the laboratory, conditions equivalent to curved spacetimes. Experiments based on these models allow us to study how spacetime structure influences the quantum behavior of the vacuum, bridging theory and observation and deepening our understanding of the interface between gravity and quantum mechanics.
Copyright (c) 2025 Lucas Tobias de Paula, Murillo Spadin Domingues, Maurício Richartz https://creativecommons.org/licenses/by/4.0
A forgotten Pioneer: Guido Beck and the prediction of gravitational waves
In 1925, the young Austrian physicist Guido Beck obtained the first exact solution to the equations of general relativity that exhibits the phenomenon of energy transport via gravitational waves. Despite its relevance and pioneering character, Beck's work remained unknown to the physics community for decades. Here we present a translation into Portuguese of the original article, written in German, in which Beck presents these results, along with an overview of the early years of his career, when he worked in the field of general relativity.
Copyright (c) 2025 Alexandre Sampaio da Cruz, Rafael Velloso, Antonio Augusto Passos Videira https://creativecommons.org/licenses/by/4.0
The rebirth of general relativity: theses and historiographical perspectives
In this article, we discuss the thesis, common among physicists and historians, that, after three decades of stagnation, there was a “renaissance” of interest in general relativity in the 1950s and 1960s. We present two versions of this thesis: one places the shift in the 1950s, following the first conferences dedicated to general relativity, and the other identifies the shift in the 1960s, due to advancements in astrophysics. We review the main arguments supporting this thesis by physicists and historians, recall some of the criticisms it has received, and analyze the key historical evidence that emerges in this historiographical debate. Finally, we reflect on the validity of this thesis and on the current challenges in research on the history of general relativity.
Copyright (c) 2025 Juliana Correia Ferreira, Juliana Youssef, Thiago Hartz https://creativecommons.org/licenses/by/4.0