The First Law Of Mechanics In General Relativity Isochrone Orbits In Newtonian Gravity

The thesis tackles two distinct problems of great interest in gravitational mechanics - one relativistic and one Newtonian. The relativistic one is concerned with the "first law of binary mechanics", a remarkably simple variational relation that plays a crucial role in the modern understanding of the gravitational two-body problem, thereby contributing to the effort to detect gravitational-wave signals from binary systems of black holes and neutron stars. The work reported in the thesis provides a mathematically elegant extension of previous results to compact objects that carry spin angular momentum and quadrupolar deformations, which more accurately represent astrophysical bodies than mere point particles. The Newtonian problem is concerned with the isochrone problem of celestial mechanics, namely the determination of the set of radial potentials whose bounded orbits have a radial period independent of the angular momentum. The thesis solves this problem completely in a geometrical way and explores its consequence on a variety of levels, in particular with a complete characterisation of isochrone orbits. The thesis is exceptional in the breadth of its scope and achievements. It is clearly and eloquently written, makes excellent use of images, provides careful explanations of the concepts and calculations, and it conveys the author's personality in a way that is rare in scientific writing, while never sacrificing academic rigor.

The thesis tackles two distinct problems of great interest in gravitational mechanics — one relativistic and one Newtonian. The relativistic one is concerned with the "first law of binary mechanics", a remarkably simple variational relation that plays a crucial role in the modern understanding of the gravitational two-body problem, thereby contributing to the effort to detect gravitational-wave signals from binary systems of black holes and neutron stars. The work reported in the thesis provides a mathematically elegant extension of previous results to compact objects that carry spin angular momentum and quadrupolar deformations, which more accurately represent astrophysical bodies than mere point particles. The Newtonian problem is concerned with the isochrone problem of celestial mechanics, namely the determination of the set of radial potentials whose bounded orbits have a radial period independent of the angular momentum. The thesis solves this problem completely in a geometrical way and explores its consequence on a variety of levels, in particular with a complete characterisation of isochrone orbits. The thesis is exceptional in the breadth of its scope and achievements. It is clearly and eloquently written, makes excellent use of images, provides careful explanations of the concepts and calculations, and it conveys the author’s personality in a way that is rare in scientific writing, while never sacrificing academic rigor.

This volume is a collection of scholarly articles on the Mach Principle, the impact that this theory has had since the end of the 19th century, and its role in helping Einstein formulate the doctrine of general relativity. 20th-century physics is concerned with the concepts of time, space, motion, inertia and gravity. The documentation on all of these makes this book a reference for those who are interested in the history of science and the theory of general relativity

This is a book about the history of the science of inertia. Nobody denies the existence of the forces of inertia, but they are branded as “fictitious” because they do not fit smoothly into modern physics. Named by Kepler and given mathematical form by Newton, the force of inertia remains aloof because it has no obvious local cause. At the end of the 19th century, Ernst Mach bravely claimed that the inertia of an object was the result of its instantaneous interaction with all matter in the universe.Many other well-known physicists, including Aristotle, Galileo, Descartes and Einstein, are shown to have tackled this difficult subject. The book also concentrates on inertia research in the 20th century, taking place under the shadow of general relativity, which is seen as uncomfortable with Mach's principle. A Newtonian paradigm, based on action-at-a-distance forces, is discussed throughout the book, allowing the revival of Mach's principle as the only coherent explanation of the inertia forces which play such an important role in the laboratory and in the cosmos.

Newtons theory of gravitation is the grandest and the most enduring physical theory ever created. Today, more than 300 years after it was first conceived, Newton''s theory of gravitation is still the basic working theory of astronomers and of all the scientists dealing with space exploration and celestial mechanics. However, Newton''s theory of gravitation has serious defects: it is incapable of accounting for certain fine details of planetary motion; it does not provide any information on the temporal aspect of gravitational interactions; it cannot be reconciled with the principle of causality and with the law of conservation of momentum when it is applied to time-dependent gravitational systems.This book extends and generalizes Newton''s theory of gravitation, makes it free from the above defects, makes it fully applicable to all possible gravitational systems, and provides a large variety of methods for calculating gravitational interactions between moving or stationary bodies of all shapes, sizes and configurations.The starting point of the generalization of Newton''s theory of gravitation developed in this book is the idea that gravitational interactions are mediated by two force fields: the gravitational field proper created by all masses and acting upon all masses, and the "cogravitational" field created by moving masses only and acting upon moving masses only. In accordance with the principle of causality, the two fields are represented by retarded field integrals, which, for static or slowly-varying gravitational systems, yield the ordinary Newtonian gravitational field.An immediate consequence of the generalized Newtonian theory of gravitation developed on this basis is that gravitational interactions normally involve at least five different forces associated with velocities, accelerations and rotations of interacting bodies. The effects of these forces are quite remarkable. Some examples: a fast-moving mass passing a spherically-symmetric body causes the latter to rotate; a mass moving with rapidly-decreasing velocity exerts both an attractive and a repulsive force on neighboring bodies; a rotating mass that is suddenly stopped causes neighboring bodies to rotate; the differential rotation of the Sun is caused by the planets orbiting around it.The generalized theory of gravitation is fully compatible with the laws of conservation of energy and momentum. A very important result of this compatibility is the definitive explanation of the process of conversion of gravitational field energy into the kinetic energy of bodies moving under the action of gravitational fields.The generalized theory of gravitation predicts the existence of gravitation-cogravitational waves and explains how such waves can be generated.The generalized theory of gravitation also indicates the existence of antigravitational (repulsive) fields and mass formations. A cosmological consequence of such fields and mass formations is a periodic expansion and contraction of the Universe. Another consequence is that the actual mass of the Universe may be much larger than the mass revealed by an analysis of gravitational attraction in the galaxies.It is natural to compare the various consequences of the generalized theory of gravitation with the consequences of the general relativity theory. In this regard the following three remarks should be made.First, there are no observable gravitational effects revealed by the general relativity theory that do not have their counterparts in the generalized theory of gravitation.Second, the generalized theory of gravitation describes a vastly larger number of gravitational effects than those described by the general relativity theory.Third, numerical values for gravitational effects predicted by the general relativity theory are usually different from the corresponding values predicted by the generalized theory of gravitation; the difference is almost always a consequence of greater complexity and depth of gravitational interactions revealed by the generalized theory of gravitation.Although this book presents the results of original research, it is written in the style of a textbook and contains numerous illustrative examples demonstrating various applications of the generalized Newtonian theory of gravitation developed in the book.

This book focuses on the phenomena of inertia and gravitation, one objective being to shed some new light on the basic laws of gravitational interaction and the fundamental nature and structures of spacetime. Chapter 1 is devoted to an extensive, partly new analysis of the law of inertia. The underlying mathematical and geometrical structure of Newtonian spacetime is presented from a four-dimensional point of view, and some historical difficulties and controversies - in particular the concepts of free particles and straight lines - are critically analyzed, while connections to projective geometry are also explored. The relativistic extensions of the law of gravitation and its intriguing consequences are studied in Chapter 2. This is achieved, following the works of Weyl, Ehlers, Pirani and Schild, by adopting a point of view of the combined conformal and projective structure of spacetime. Specifically, Mach’s fundamental critique of Newton’s concepts of ‘absolute space’ and ‘absolute time’ was a decisive motivation for Einstein’s development of general relativity, and his equivalence principle provided a new perspective on inertia. In Chapter 3 the very special mathematical structure of Einstein’s field equations is analyzed, and some of their remarkable physical predictions are presented. By analyzing different types of dragging phenomena, Chapter 4 reviews to what extent the equivalence principle is realized in general relativity - a question intimately connected to the ‘new force’ of gravitomagnetism, which was theoretically predicted by Einstein and Thirring but which was only recently experimentally confirmed and is thus of current interest.

This book shows that the strong interaction forces, which keep hadrons and nuclei together, are relativistic gravitational forces exerted between very small particles in the mass range of neutrinos. First, this book considers the motion of two or three charged particles under the influence of electrostatic and gravitational forces only, which shows that bound states are formed by following the same semi-classical methodology used by Bohr to describe the H atom. This approach is also coupled with Newton’s gravitational law and with Einstein’s special relativity. The results agree with experiments on the masses, binding energies, radii, angular moments and magnetic moments of hadrons. The model provides the means to rationalize all the main experimental features of the strong force. Some of the implications for the unification of forces and the nature of our micro-cosmos and macro-cosmos are also discussed. The creation of mass itself, in other words, of hadrons from particles as light as neutrinos, can now be modeled in a straightforward manner.