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.

"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.

"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.

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).

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.

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. 

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.

An exploration of the history and science of timekeeping, from the earliest sundials to the latest atomic clocks. The book describes various methods and devices used to measure time, including mechanical clocks, water clocks, and astronomical observations. The author also explains the principles behind modern time standards like Greenwich Mean Time (GMT).This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it.This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

"Experts Plebaânski and Krasiânski provide a thorough introduction to the tools of general relativity and relativistic cosmology, guiding advanced students through complete derivations of the results. Starting with a short course on differential geometry, the main text describes relativity as a physical theory"--

In addition to expanding and clarifying a number of sections of the first edition, it generalizes the analysis that eliminates the noncausal pre-acceleration so that it applies to removing any pre-deceleration as well. It also introduces a robust power series solution to the equation of motion that produces an extremely accurate solution to problems such as the motion of electrons in uniform magnetic fields.

This book offers a primer on the fundamentals and applications of the Geroch-Held-Penrose (GHP) calculus, a powerful formalism designed for spacetimes that occur frequently in the teaching of General Relativity. Specifically, the book shows in detail the power of the calculus when dealing with spherically symmetric spacetimes. After introducing the basics, a new look at all the classical spherically symmetric black hole solutions is given within the GHP formalism. This is then employed to give new insights into the Tolman-Oppenheimer-Volkoff equations for stellar structure, including a derivation of new exact anisotropic fluid solutions. Finally, a re-writing of some essential features of black hole thermodynamics within the GHP formalism is performed. The book is based on the authors' lecture notes, used in their undergraduate and graduate lectures and while supervising their upper undergraduate and graduate students. To fully benefit from this concise primer, readers only need an undergraduate background in general relativity.