Relativitetsfysik

Tidsrummet mellem to begivenheder er afhængigt af, hvor hurtigt en observatør bevæger sig. Det er en af de besynderlige konsekvenser af Albert Einsteins specielle relativitetsteori fra 1905, der er en grundsten i den moderne fysik. I Speciel Relativitetsteori forklarer Ulrik Uggerhøj tid og rum. Han udleder bl.a. fundamentet for fænomener som tidsforlængelse, længdeforkortning og Lorentz-transformationerne, undersøger tyngdens indflydelse på tidens gang, sorte huller og gravitationsbølger og præsenterer løsninger på flere af teoriens tilsyneladende paradokser. Bogen indeholder forslag til læseforløb fra gymnasiale studieretningsprojekter til det avancerede universitetsniveau.

'If you want to remember why you once fell in love with the idea of the cosmos, or want to fall in love with it for the first time, then this book is for you' ObserverFrom Carlo Rovelli, the bestselling author of Seven Brief Lessons on Physics, this is a story of wonder, new worlds and why the end is just the beginningLet us journey into the heart of a black hole. Let us slip beyond its boundary, the horizon, and tumble - on and on - down this crack in the universe. As we plunge, we'll see geometry fold, we'll feel the equations draw tight around us. Eventually, we'll pass it: the remains of a star, deep and dense and falling further far. And then - the bottom. Where time and space end, and the white hole is born . . .With lightness and magic, here Carlo Rovelli traces the ongoing adventure of his own cutting-edge research, of the uncertainty and joy of going where we've not yet been. Guiding us to the edge of theory and experiment, he invites us to go beyond, to experience the fever and the disquiet of science. Here is the extraordinary life of a white hole.A BOOK OF THE YEAR ACCORDING TO THE FINANCIAL TIMES * SUNDAY TELEGRAPH * NEW STATESMAN * NEW SCIENTIST

"The most trusted explainer of the most mind-boggling concepts pulls back the veil of mystery that has too long cloaked the most valuable building blocks of modern science. Sean Carroll, with his genius for making complex notions entertaining, presents in his uniquely lucid voice the fundamental ideas informing the modern physics of reality. Physics offers deep insights into the workings of the universe but those insights come in the form of equations that often look like gobbledygook. Sean Carroll shows that they are really like meaningful poems that can help us fly over sierras to discover a miraculous multidimensional landscape alive with radiant giants, warped space-time, and bewilderingly powerful forces. High school calculus is itself a centuries-old marvel as worthy of our gaze as the Mona Lisa. And it may come as a surprise the extent to which all our most cutting-edge ideas about black holes are built on the math calculus enables. No one else could so smoothly guide readers to grasping the very equation Einstein used to describe his theory of general relativity. In the tradition of the legendary Richard Feynman lectures presented sixty years ago, this book is an inspiring, dazzling introduction to a way of seeing that will resonate across cultural and generational boundaries for many years to come"--

Endeavors to explain Einstein's general theory of relativity, beginning with the equivalence principle and covering the necessary mathematics of Riemannian spaces and tensor calculus, offering readers a deeper understanding of the universe's real structure.

Perfect for those interested in physics but who are not physicists or mathematicians, this book makes relativity so simple that a child can understand it. By replacing equations with diagrams, the book allows non-specialist readers to fully understand the concepts in relativity without the slow, painful progress so often associated with a complicated scientific subject. It allows readers not only to know how relativity works, but also to intuitively understand it.

"This graduate textbook covers the basic formalism of supergravity, as well as a wide range of its modern applications, suitable for a focused first course. Assuming a working knowledge of quantum field theory, it gives Ph.D. students the tools they need to do research that uses supergravity"--

En esta oportunidad la idea es traer al presente lo realizado en el pasado, mostrando lo valioso que es cuando un estudiante se involucra y lo hace con agrado, dejando de lado las ecuaciones, sin dejar de lado la Física.Hoy damos inicio con "Una Física Diferente" cuya temática principal son los cuentos de Física realizados por estudiantes ya sean de Establecimientos educacionales, como universitaria.

O significativo défice energético assim observado leva as famílias a fazer um uso intensivo e abusivo de fontes alternativas de energia, nomeadamente lenha e carvão vegetal, o que aumenta a pressão sobre as florestas com um impacto negativo sobre o clima. Parece que as dificuldades no acesso à energia pesam mais nas mulheres do que nos homens, com a consequência de reduzir substancialmente o tempo que deveriam ter dedicado a actividades educativas, sociais e geradoras de rendimentos. Na República Democrática do Congo, as mulheres estão envolvidas em 90% das actividades agrícolas e são os principais actores em actividades informais para a sobrevivência das famílias. Como as suas necessidades de madeira são reduzidas, os beneficiários também fazem economias financeiras que lhes dão a oportunidade de satisfazer outras necessidades.

A simple green combustion synthesis route was used to synthesize the CeO2 NPs using T. I. fruit extract as fuel. The structural, optical and catalytic properties of as-formed as well as calcined CeO2 NPs were studied in detail. From PXRD patterns confirmed the cubic phase of prepared CeO2 NPs. The effect of fuel on the crystallite size, energy band gap and PL properties were studied in detail. The prepared CeO2 NPs were agglomerated in nature with large number of surface voids were observed from the scanning electron microscope. The particle size was estimate from TEM results and found to be in the range of 5- 40 nm which was in good agreement with the PXRD results. From the chromaticity diagrams it was noticed that a blue color emission from the prepared samples. Further, modified electrodes by CeO2 NPs exhibits enhanced electrochemical sensing properties and hence can be used to fabricate the electrochemical sensing devices. The CeO2 NPs also showed good photocatalytic activity with respect to variation in pH and catalytic load. The above all results of CeO2 were fruitful in the fabrication of display devices, electrochemical sensing devices as well as a good Photocatalyst.

One of the effective instruments for examining atomic and molecular structures and widely used to examine a wide variety of chemicals is spectroscopy. The goal of the current book is to investigate several pharmacological substances utilizing theoretical calculation methods and spectroscopic approaches. It has also made it possible to use a commercial FT-IR spectrometer's extensive data handling capabilities. These techniques are used to measure the vibrational energy levels in a sample. Its applications are basic drug research and structural elucidation, formulation development and validation, quality control processes for incoming and outgoing materials, and packaging testing. The goal of obtaining an accurate understanding of the molecules' vibrational spectra is currently the focus of extensive research. The study of molecular dynamics has greatly been benefited from the density functional theory approach of examining molecular vibrations. This work has determined the vibrational frequencies and various properties of certain prominent natural particles using the Gaussian program, which is developed for performing DFT estimations.

In recent decades, twistor theory has grown into an irreplaceable tool for the study of scattering amplitudes in gauge theory and gravity. This book introduces the reader to cutting-edge advances in twistor theory and its applications to general relativity. The problem of graviton scattering in four dimensions is shown to be dual to dramatically simpler computations in a two-dimensional CFT known as a twistor sigma model. Twistor sigma models are the first step toward a holographic description of gravity in asymptotically flat space-times. They underpin the infinitely many asymptotic symmetries of flat space physics discovered in celestial holography, and extend them to exciting new arenas like curved space-times. They also yield intrinsically mathematical results in the field of hyperkähler manifolds. This volume will be of broad interest to students and researchers looking for an accessible entry point into twistor geometry, scattering amplitudes, and celestial holography. It will also provide an invaluable reference for specialists by bringing together results from a host of different disciplines.

"Modern physics is dazzling. What is it about space that will not let an object move faster than light? Why does mass increase and time slow at extremely high velocities? Why is it impossible to know where a particle is if its momentum is known? In everyday experience, why do we feel acceleration but not velocity? These physical phenomena are well known, and their effects are easily calculated, but the dazzle remains. Why do they happen at extreme dimensions -- the very fast, the very small, the very massive, the very distant? The key revolves around the role of the observer, or, in other words, consciousness. Without an observer, the existence of an object itself becomes problematic. It is time to look again at what dimensions are and how they relate to consciousness"--

OSAU-3 Presents What, When, Where, Why, How and Who Is Us? an AWTbook(TM).

We know that matter exists in any one of the three states namely solid, liquid and gas. At the atomic level, these states of matter are distinguished from each other in terms of the nature of bonding among their atoms or molecules. Due to the unique nature of their atomic or molecular bonding, solids, liquids and gases possess characteristics macroscopic properties. In this book, we will study some of these properties of matter such as surface tension, viscosity, and elasticity. These properties have wide-ranging applications in engineering, industry, and even in our day-to-day lives such as twisting couples, cantilevers, the flow of liquid, the law of hydrostatic pressure, filter pump, surface tension, etc. This book also helps to create interest among the readers to know the magic of matter.

In this meticulously researched and beautifully crafted biography, you'll walk in the footsteps of a young einstein, whose insatiable curiosity led him from the unassuming town of ulm, germany, to the pinnacle of scientific achievement. Discover the genius behind the theory of relativity, the revolutionary equation e=mc², and his audacious challenges to the conventions of physics.But this biography goes beyond science. You'll uncover the human side of einstein, the advocate for peace and civil rights, and the man whose wisdom and wit continue to inspire. Inside you will read about...A genius shows up with a deformed headThe odd shaped head starts to readEinstein had a "miracle year"Einstein finds he has enemiesAlbert had his problems tooDid einstein have a 3rd son? You decideThe end is soon to comeIn his later years albert einstein was known as a gentle and lovable man who forgot his socks and rarely combed his hair. But he was much more than an absent-minded genius. He was a fierce individualist, who, as a teenager, renounced his german citizenship rather than serve in the army. As a rebel against every form of authority, an outspoken enemy of anti-semitism and fascism, and a socialist with an enduring commitment to social justice, you will learn in this book that even as einstein was setting newtonian physics on its ear, he considered his most important work to be about something very different: the bettering of humanity.

In the Collection ¿Quantum Gravity¿ the first article presents a new method for constructing quantum gravity, based on the equations of Einstein¿s general theory of relativity. It is shown that the natural space-time boundary is the Planck length. A new uncertainty relation between the gravitational radius of a particle and its position has been found. The basic equation of quantum gravity has been established. The inevitable nature of the three-dimensionality of space is shown. A hypothesis has been put forward about the nature of the singularities of black holes and the Metagalaxy. The second article establishes Bohr¿s general principle of complementarity, its extension to other areas of reality and its philosophical significance. The last article builds a visual model of special relativity and shows its role in scientific knowledge.

This book focuses more on the lower dimension of the Cosmological model of the universe through the General Theory of Relativity. In this book, we have to drive and solve the different line elements with different equations of state in the (2+1)-Dimensional model. This book is more precise for lower-dimensional problems. We have solved cosmological modal in the modified theory of relativity as well as in another alternative theories of relativities.

One of the main unanswered question of modern Physics is "How does gravity behave at small scales?". The aim of this thesis is to illustrate in a comprehensive but accessible way how to look for deviations from Einstein's theory of General Relativity in this regime, looking at the simplest celestial bodies: static and spherically symmetric ones.With a conservative and bottom-up approach, at smaller scales the first corrections to the action of General Relativity are generally considered to be terms quadratic in the curvature tensors; while these modifications do not cure the inconsistency between gravity and quantum mechanics, the solutions of this theory are plausible candidates to be the first-order corrections of the classical ones.Even with such simple modifications, a striking picture emerges from the study of isolated objects: the unique Schwarzschild solution of General Relativity is only a rare bird in the set of solutions, with non-Schwarzschild black holes, wormholes and naked singularities appearing as possible substitutes.Tailored to graduate students and researchers entering this field, this thesis shows how to construct these new solutions from action principles, how to characterize their metric, how to study their physical properties, such as their stability or Thermodynamics, and how to look for phenomenological signatures.

This concise book reviews methods used for gluing space-time manifolds together. It is therefore relevant to theorists working on branes, walls, domain walls, concepts frequently used in theoretical cosmology, astrophysics, and gravity theory. Nowadays, applications are also in theoretical condensed matter physics where Riemannian geometry appears. The book also reviews the history of matching conditions between two space-time manifolds from the early times of general relativity up to now.

This book provides an introduction to classical celestial mechanics. It is based on lectures delivered by the authors over many years at both Padua University (MC) and V.N. Karazin Kharkiv National University (EB). The book aims to provide a mathematical description of the gravitational interaction of celestial bodies. The approach to the problem is purely formal. It allows the authors to write equations of motion and solve them to the greatest degree possible, either exactly or by approximate techniques, when there is no other way. The results obtained provide predictions that can be compared with the observations. Five chapters are supplemented by appendices that review certain mathematical tools, deepen some questions (so as not to interrupt the logic of the mainframe with heavy technicalities), give some examples, and provide an overview of special functions useful here, as well as in many other fields of physics. The authors also present the original investigation of torus potential. This book is aimed at senior undergraduate students of physics or astrophysics, as well as graduate students undertaking a master's degree or Ph.D.

Despite successes of modern physics, the existence of dark energy and matter is indicative that conventional mechanical accounting is lacking. The most basic of all mechanical principles is Newton's second law, and conventionally, energy is just energy whether particle or wave energy. In this monograph, Louis de Broglie's idea of simultaneous existence of both particle and associated wave is developed, with a novel proposal to account for mass and energy through a combined particle-wave theory. Newton's second law of motion is replaced by a fully Lorentz invariant reformulation inclusive of both particles and waves.  The model springs from continuum mechanics and forms a natural extension of special relativistic mechanics. It involves the notion of "e;force in the direction of time"e; and every particle has both particle and wave energies, arising as characteristics of space and time respectively. Dark matter and energy then emerge as special or privileged states occurring for alignments of spatial forces with the force in the direction of time. Dark matter is essentially a backward wave and dark energy a forward wave, both propagating at the speed of light.  The model includes special relativistic mechanics and Schrodinger's quantum mechanics, and the major achievements of mechanics and quantum physics.  Our ideas of particles and waves are not yet properly formulated, and are bound up with the speed of light as an extreme limit and particle-wave demarcation. Sub-luminal particles have an associated superluminal wave, so if sub-luminal waves have an associated superluminal particle, then there emerges the prospect for faster than light travel with all the implications for future humanity. Carefully structured over special relativity and quantum mechanics, Mathematics of Particle-Wave Mechanical Systems is not a completed story, but perhaps the first mechanical model within which such exalted notions might be realistically and soberly examined. If ultimately the distant universe become accessible, this will necessitate thinking differently about particles, waves and the role imposed by the speed of light. The text constitutes a single proposal in that direction and a depository for mathematically related results.  It will appeal to researchers and students of mathematical physics, applied mathematics and engineering mechanics. 

About the BookThe use of the principles of relativity began in the mid-seventeenth century with Galileo, which is known as classical relativity or Newtonian relativity. but these equations faced difficulties when applied to Maxwell's equations in electromagnetism, and they failed in certain astronomical measurements. Therefore, Lorentz transformations were formulated at the end of the nineteenth century. Einstein adopted the Lorentz transformations and considered Newton's relativity as outdated and insufficient, leading him to develop his theory of relativity as an alternative.Critiques and objections to Einstein's theory of relativity have indeed persisted over time. Some have argued that it goes against common sense and appears unrealistic. Additionally, there have been debates about its compatibility with the principle of relativity concerning the constancy of physical laws when observed by moving observers and its application to objects moving according to the law of self-relativity.Many physicists published numerous books and research papers attempting to refute Einstein's theory of relativity. However, all were neglected as they did not provide an alternative and could not prove the failure of Einstein's relativity theory. Einstein was assured that his theory could not be refuted with a practical experiment as it is impossible to achieve a speed close to the speed of light.Today, the remarkable advancement of artificial intelligence in accessing scientific information has given us a rare opportunity that was not available to Einstein. I am not alone in seeing the rapid development of technology and new horizons arising daily. Artificial intelligence feeds us information and ideas, from articles and evidence to online symposiums and deep learning. That being said, we no longer need to put much effort into seeking the truth since we can recognise the tools used by everyone, be inspired by fascinating projects, and search for experts' help. That makes what we introduce of immense importance, which I discovered in Relativity, after seven years of concentrated study to provide evidence of the failure of Einstein's relativity, modify Newton's relativity, and establish the third relativity theory.

Our vast Universe is filled with an enormous amount of matter and energy, which are the source of large gravitational potentials affecting all physical phenomena. Because this fact about the size and contents of the Universe was not known when our fundamental theories of dynamics and relativity were completed by the 1920s, the current theories - based as they are in empty space - fail to incorporate cosmic gravity. Though the current theories are consistent with the majority of empirical facts, there are some crucial discrepancies, which demand a drastic shift to a cosmic gravitational paradigm for the theories of relativity and dynamics. The book is a detailed and widely accessible account of this paradigm, called Cosmic Relativity, supported by ample empirical evidence. It is established that all motional relativistic effects are cosmic gravitational effects. The new theory of Cosmic Relativity solves and answers all outstanding questions and puzzles about dynamics and relativity.