All physicists would agree that one of the most fundamental problems of the 21st century physics is the dimensionality of the world. In the four-dimensional world of Minkowski (or Minkowski spacetime) the most challenging problem is the nature of the temporal dimension. In Minkowski spacetime it is merely one of the four dimensions, which means that it is entirely given like the other three spacial dimensions. If the temporal dimension were not given in its entirety and only one constantly changing moment of it existed, Minkowski spacetime would be reduced to the ordinary three-dimensional space. But if the physical world, represented by Minkowski spacetime, is indeed four-dimensional with time being the fourth dimension, then such a world is drastically different from its image based on our perceptions.

Bad Hofgastein who made the very successful Salzburger Abend with indi- nous music from Salzburg possible. Special thanks also to the former director of the Institute of Astronomy in Vienna, Prof. Paul Jackson for his generous private donation. We should not forget our hosts Mr. and Mrs. Winkler and their employees from the hotel who made the stay quite enjoyable. None of us will forget the very last evening, when the staff of kitchen under the le- ership of the cook himself came to offer us as farewell the famous Salzburger Nockerln, a traditional Austrian dessert. Everyone got a lot of scienti?c input during the lectures and the discussions and, to summarize, we all had a spl- did week in Salzburg in the Hotel Winkler. We all hope to come again in 2008 to discuss new results and new perspectives on a high level scienti?c standard in the Gasteinertal. Rudolf Dvorak and Sylvio Ferraz-Mello Celestial Mechanics and Dynamical Astronomy (2005) 92:1-18 (c) Springer 2005 DOI 10. 1007/s10569-005-3314-7 FROM ASTROMETRY TO CELESTIAL MECHANICS: ORBIT DETERMINATION WITH VERY SHORT ARCS (Heinrich K. Eichhorn Memorial Lecture) 1 2 ? ' ANDREA MILANI and ZORAN KNEZEVIC 1 Department of Mathematics, University of Pisa, via Buonarroti 2, 56127 Pisa, Italy, e-mail: milani@dm. unipi. it 2 Astronomical Observatory, Volgina 7, 11160 Belgrade 74, Serbia and Montenegro, e-mail: zoran@aob. bg. ac.

Our current perspective has arisen over millennia, through falling apples, elevator thought experiments and stars spiralling into black holes; Free fall and self-force in general relativity.

In fact, we do not have in mind to make a 1:1 reflection of the school. The ordering has been rearranged to tie articles together more coherently. We also propose to ask authors to focus their contributions according to the title we have suggested and to give a more complete description of current and future directions. We expect this will add to the volume s value for all anticipated readers. This volume has the unique feature of presenting a multifaceted approach to mass, which is intended mainly for graduate students and young doctoral researchers in the field of gravitation, who might be hoping to find a concise and introductory presentation of advanced topics outside their research field.

It is true that research from the infinitesimal scale of particle physics to the cosmic scale of the universe is concerned with the mass. While there have been spectacular advances in physics during the past century, mass still remains as a mysterious entity at the forefront of current research. Particle accelerators in the quest for the Higgs boson, laser interferometers sensitive enough to respond to gravitational waves, equivalence principle tests and detectors for dark matter are among the most ambitious and expensive experiments that fundamental physics has ever envisaged, and strongly attest to this fact. Both the self-force and radiation reaction are, in fact, lively topics of research. Related to the nature of motion, they have been hotly debated within general relativity from the inception of the theory. Recent developments have shown that radiation reaction is unavoidable in determining the gravitational waveforms emitted from a source such as the capture of a solar mass star by super-massive black hole (EMRI).

The main theme of this volume is mass and its motion within general relativity (and other theories of gravity), particularly for compact bodies, to which many articles directly refer. Within this framework, there are chapters on post-Newtonian and related methods (Blanchet, Gourgoulhon and Jaramillo, Nagar, Schafer), as well as on the self-force approach to the analysis of motion (Barack, Detweiler, Gal tsov, Poisson, Wald, Whiting), summarised along with an historic development of the field (Spallicci) and a snapshot on the state of the art (Burko). Note that self-acceleration depends directly on the mass of the body experiencing it. Mass itself is essential for this effect on motion.

Auxiliary chapters set the context for these theoretical contributions within the wider context of experimental physics. The space mission LISA (Jennrich) has been designed to detect the gravitational waves from EMRI captures, while other LISA sources may have electromagnetic counterparts (van Putten). Motion in modern gravitation must confront alternative theories (Esposito-Farese) and it must to be comprehensible within a quantum context (Noui), and demands an account of the relation between vacuum fluctuations and inertia (Jaekel and Reynaud). A volume centred on the fundamental role of mass in physics should face issues related to the basic laws of mechanics proposed by Newton (Lammerzahl) and precision measurements (Davis).

The role of the Higgs boson within physics is to give a mass to elementary particles (Djouadi), by interacting with all particles required to have a mass and thereby inducing inertia.

Moreover, most mass in the universe is dark, and only indirectly detected. A proposed alternative to dark matter theories is due to a modified theory of gravity (Esposito-Farese) such as MOND (MOdified Newtonian Dynamics). Even if general relativity does not explain gravity, there still remains the fundamental problem of reconciling any theory of gravity with the physics of quantum fields (Noui), itself so well verified experimentally.

A IUTAM symposium on 'Waves in Liquid/Gas and Liquid/Vapor Two-Phase Systems' was held in Kyoto, Japan, 9-13 May 1994. Sixty-three scientists partici pated coming from ten countries, and forty-two lectures were presented. The list of participants and the program are included in this volume. The symposium was held in response to the request of the participants in the IUTAM symposium 'Adiabatic Waves in Liquid-Vapor System' held at Gottingen in 1989. At that time, the need for another symposium in about five years had been indicated by all the participants. This symposium intends to develop the subject of wave properties in more general liquid-gas two-phase systems. Topics in this symposium may be classified as (1) waves in liquid-gas bubble systems including interfacial effects, (2) waves in gas( vapor )-droplets systems, (3) waves in films or stratified systems, (4) waves with liquid-vapor transition, (5) waves with vapor-liquid transition, (6) wave propagation near the critical point and (7) waves with low pressure effect. As for topic (1), experiments, numerical simulations and analytical approaches to waves in bubly liquids were discussed. The importance of interbubble interactions through the liquid-field is now well established at least in terms of potential theory. There was also a progress concerning the well-posedness of governing equations for void waves. For pressure waves there were some new phenomena, such as bubble cluster formation and the occurrence of three-dimensional structures, in addition to a progress from more qualitative studies to quantitative ones."

This open access monograph offers a detailed study and a systematic defense of a key intuition we typically have, as human beings, with respect to the nature of time: the intuition that the future is open, whereas the past is fixed. For example, whereas it seems unsettled whether there will be a fourth world war, it is settled that there was a first world war. The book contributes, in particular, three major and original insights. First, it provides a coherent, non-metaphorical, and metaphysically illuminating elucidation of the intuition. Second, it determines which model of the temporal structure of the world is most appropriate to accommodate the intuition, and settles on a specific version of the Growing Block Theory of time (GBT). Third, it puts forward a naturalistic foundation for GBT, by exploiting recent results of our best physics (viz. General Relativity, Quantum Mechanics, and Quantum Gravity). Three main challenges are addressed: the dismissal of temporal asymmetries as non-fundamental phenomena only (e.g., thermodynamic or causal phenomena), the epistemic objection against GBT, and the apparent tension between GBT and relativistic physics. It is argued that the asymmetry between the open future and the fixed past must be grounded in the temporal structure of the world, and that this is neither precluded by our epistemic device, nor by the latest approaches to Quantum Gravity ( e.g., the Causal Set Theory). Aiming at reconciling time as we find it in ordinary experience and time as physics describes it, this innovative book will raise the interest of both academic researchers and graduate students working on the philosophy of time. More generally, it presents contents of interest for all metaphysicians and non-dogmatic philosophers of physics. This is an open access book.

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 thesis sheds valuable new light on the second-order cosmological perturbation theory, extensively discussing it in the context of cosmic microwave background (CMB) fluctuations. It explores the observational consequences of the second-order vector mode, and addresses magnetic field generation and the weak lensing signatures, which are key phenomena of the vector mode. The author demonstrates that the second-order vector mode, which never appears at the linear-order level, naturally arises from the non-linear coupling of the first-order scalar modes. This leads to the remarkable statement that the vector-order mode clearly contributes to the generation of cosmological magnetic fields. Moreover, the weak lensing observations are shown to be accessible to the vector mode. On the basis of ongoing and forthcoming observations, the thesis concludes that the second-order vector mode is detectable.

Devoted to the history of general relativity, this text provides reviews from scholars all over the world. Many of the papers originated at the Third International Conference on the History of General Relativity, held at the University of Pittsburgh in the summer of 1991. Topics covered include: disputes with Einstein; the empirical basis of general relativity; variational principles in general relativity; the reception and development of general relativity; and cosmology and general relativity.

This book is the first all-encompassing exploration of the role of demons in philosophical and scientific thought experiments. In Part I, the author explains the importance of thought experiments in science and philosophy. Part II considers Laplace's Demon, whose claim is that the world is completely deterministic. Part III introduces Maxwell's Demon, who - by contrast - experiences a world that is probabilistic and indeterministic. Part IV explores Nietzsche's thesis of the cyclic and eternal recurrence of events. In each case a number of philosophical consequences regarding determinism and indeterminism, the arrows of time, the nature of the mind and free will are said to follow from the Demons's worldviews. The book investigates what these Demons - and others - can and cannot tell us about our world.

This book deals with diffraction radiation, which implies the boundary problems of electromagnetic radiation theory. Diffraction radiation is generated when a charged particle moves near a target edge at a distance ( - Lorentz factor, - wave length). Diffraction radiation of non-relativistic particles is widely used to design intense emitters in the cm wavelength range. Diffraction radiation from relativistic charged particles is important for noninvasive beam diagnostics and design of free electron lasers based on Smith-Purcell radiation which is diffraction radiation from periodic structures. Different analytical models of diffraction radiation and results of recent experimental studies are presented in this book. The book may also serve as guide to classical electrodynamics applications in beam physics and electrodynamics. It can be of great use for young researchers to develop skills and for experienced scientists to obtain new results.

This thesis covers several theoretical aspects of WIMP (weakly interacting massive particles) dark matter searches, with a particular emphasis on colliders. It mainly focuses on the use of effective field theories as a tool for Large Hadron Collider (LHC) searches, discussing in detail the issue of their validity, and on simplified dark matter models, which are receiving a growing attention from the physics community. It highlights the theoretical consistency of simplified models, which is essential in order to correctly exploit their potential and for them to be a common reference when comparing results from different experiments. This thesis is of interest to researchers (both theorists and experimentalists) in the field of dark matter searches, and offers a comprehensive introduction to dark matter and to WIMP searches for students and non-experts.

This book offers a comprehensive and complete description of a new scheme to stabilize the power of a laser on a level needed for high precision metrology experiments. The novel aspect of the scheme is sensing power fluctuations via the radiation pressure driven motion they induce on a micro-oscillator mirror. It is shown that the proposed technique can result in higher signals for power fluctuations than what is achieved by a direct power detection, and also that it enables the generation of a strong bright squeezed beam. The book starts with the basics of power stabilization and an overview on the current state of art. Then, detailed theoretical calculations are performed, and the advantages of the new scheme are highlighted. Finally, a proof-of-principle experiment is described and its results are analyzed in details. The success of the work presented here paves a way for achieving high power stability in future experiments and is of interest for high precision metrology experiments, like gravitational wave detectors, and optomechanical experiments. Nominated as an outstanding PhD thesis by the Gravitational Wave International Committee.

Divided into four parts, this book covers recent developments in topics pertaining to gravity theories, including discussions on the presence of scalar fields. Part One is devoted to exact solutions in general relativity, and is mainly concerned with the results of rotating null dust beams and fluids. Also included is a panoramic vision of new research directions in this area, which would require revising certain theorems and their possible extensions within gravity theories, new aspects concerning the Ernst potentials, double Kerr spacetimes, and rotating configurations. In particular, there is a detailed discussion of totally symmetric and totally geodesic spaces, in which a method for generating (2+1)-dimensional solutions from (3+1)-dimensional solutions is given. Part Two deals with alternative theories of gravity, all of which include scalar fields and gauge fields. Here, quantum and cosmological effects, which arise from both gravity theories in four and higher dimensions and from metric-affine theories, are investigated. Part Three is devoted to cosmological and inflationary scenarios. Local effects, such as the influence of scalar fields in protogalactic interactions, numerical studies of the collapse of molecular cores, as well as the inverse inflationary problem and the blue eigenvalue spectrum of it, are considered. Moreover, the role of scalar fields as dark matter and quantum cosmology in the Bergman-Wagoner and Gowdy theories, together with the relation of the conformal symmetry and deflationary gas universe, are likewise presented. The last part of the book includes some mixed topics which are still in the experimental stage. Among them are the foundation of the Maxwell theory, a discussion on electromagnetic Thirring problems, a note on the staticity of black holes with non-minimally coupled scalar fields, and a study of the Lorentz force free charged fluids in general relativity. Thus, this book is the most up-to-date, comprehensive collection of papers on the subject of exact solutions and scalar fields in gravity and is a valuable tool for researchers in the area.

This book discusses the notion that quantum gravity may represent the "breakdown" of spacetime at extremely high energy scales. If spacetime does not exist at the fundamental level, then it has to be considered "emergent", in other words an effective structure, valid at low energy scales. The author develops a conception of emergence appropriate to effective theories in physics, and shows how it applies (or could apply) in various approaches to quantum gravity, including condensed matter approaches, discrete approaches, and loop quantum gravity.

Three eminent scientists, each well known for the clarity of their writing, present for students and researchers what is known about the internal structure, origin and evolution of White Dwarfs, Neutron Stars and Black Holes, all objects at the final stage of stellar evolution. They cover fascinating topics such as pulsation of white dwarfs, millisecond pulsars or the dynamics around black holes. The book is written for graduate students in astrophysics, but is also of interest to professional astronomers and physicists.

This book provides a completely revised and expanded version of the previous classic edition 'General Relativity and Relativistic Astrophysics'. In Part I the foundations of general relativity are thoroughly developed, while Part II is devoted to tests of general relativity and many of its applications. Binary pulsars - our best laboratories for general relativity - are studied in considerable detail. An introduction to gravitational lensing theory is included as well, so as to make the current literature on the subject accessible to readers. Considerable attention is devoted to the study of compact objects, especially to black holes. This includes a detailed derivation of the Kerr solution, Israel's proof of his uniqueness theorem, and a derivation of the basic laws of black hole physics. Part II ends with Witten's proof of the positive energy theorem, which is presented in detail, together with the required tools on spin structures and spinor analysis. In Part III, all of the differential geometric tools required are developed in detail. A great deal of effort went into refining and improving the text for the new edition. New material has been added, including a chapter on cosmology. The book addresses undergraduate and graduate students in physics, astrophysics and mathematics. It utilizes a very well structured approach, which should help it continue to be a standard work for a modern treatment of gravitational physics. The clear presentation of differential geometry also makes it useful for work on string theory and other fields of physics, classical as well as quantum.

This concise textbook introduces the reader to advanced mathematical aspects of general relativity, covering topics like Penrose diagrams, causality theory, singularity theorems, the Cauchy problem for the Einstein equations, the positive mass theorem, and the laws of black hole thermodynamics. It emerged from lecture notes originally conceived for a one-semester course in Mathematical Relativity which has been taught at the Instituto Superior Tecnico (University of Lisbon, Portugal) since 2010 to Masters and Doctorate students in Mathematics and Physics. Mostly self-contained, and mathematically rigorous, this book can be appealing to graduate students in Mathematics or Physics seeking specialization in general relativity, geometry or partial differential equations. Prerequisites include proficiency in differential geometry and the basic principles of relativity. Readers who are familiar with special relativity and have taken a course either in Riemannian geometry (for students of Mathematics) or in general relativity (for those in Physics) can benefit from this book.

A host of astrophysical measurements suggest that most of the matter in the Universe is an invisible, nonluminous substance that physicists call "dark matter." Understanding the nature of dark matter is one of the greatest challenges of modern physics and is of paramount importance to our theories of cosmology and particle physics. This text explores one of the leading hypotheses to explain dark matter: that it consists of ultralight bosons forming an oscillating field that feebly interacts with light and matter. Many new experiments have emerged over the last decade to test this hypothesis, involving state-of-the-art microwave cavities, precision nuclear magnetic resonance (NMR) measurements, dark matter "radios," and synchronized global networks of atomic clocks, magnetometers, and interferometers. The editors have gathered leading experts from around the world to present the theories motivating these searches, evidence about dark matter from astrophysics, and the diverse experimental techniques employed in searches for ultralight bosonic dark matter. The text provides a comprehensive and accessible introduction to this blossoming field of research for advanced undergraduates, beginning graduate students, or anyone new to the field, with tutorials and solved problems in every chapter. The multifaceted nature of the research - combining ideas and methods from atomic, molecular, and optical physics, nuclear physics, condensed matter physics, electrical engineering, particle physics, astrophysics, and cosmology - makes this introductory approach attractive for beginning researchers as well as members of the broader scientific community. This is an open access book.

General Relativity is a beautiful geometric theory, simple in its mathematical formulation but leading to numerous consequences with striking physical interpretations: gravitational waves, black holes, cosmological models, and so on. This introductory textbook is written for mathematics students interested in physics and physics students interested in exact mathematical formulations (or for anyone with a scientific mind who is curious to know more of the world we live in), recent remarkable experimental and observational results which confirm the theory are clearly described and no specialised physics knowledge is required. The mathematical level of Part A is aimed at undergraduate students and could be the basis for a course on General Relativity. Part B is more advanced, but still does not require sophisticated mathematics. Based on Yvonne Choquet-Bruhat's more advanced text, General Relativity and the Einstein Equations, the aim of this book is to give with precision, but as simply as possible, the foundations and main consequences of General Relativity. The first five chapters from General Relativity and the Einstein Equations have been updated with new sections and chapters on black holes, gravitational waves, singularities, and the Reissner-Nordstroem and interior Schwarzchild solutions. The rigour behind this book will provide readers with the perfect preparation to follow the great mathematical progress in the actual development, as well as the ability to model, the latest astrophysical and cosmological observations. The book presents basic General Relativity and provides a basis for understanding and using the fundamental theory.

Iconoclastic physics professor and artist Andrzej Dragan presents a unique feast of knowledge on special relativity in a straightforward, progressive manner that even a savvy high school student could follow. Encompassing the derivation of Lorentz transformations to Wigner rotations and Thomas precession; from non-inertial accelerated reference frames to event horizons, curved spacetime, and static black holes; and from the Doppler effect to relativistic structure of electromagnetism, Dragan peels back the enigmatic layers of modern physics to enable a deeper understanding of Einstein's groundbreaking theory.Comprehensive and elegantly written, full of insightful apparent paradoxes and riddles, but without any complicated math, Dragan's unique overview takes the reader well beyond the orthodox verses of standard Special Relativity to the bleeding edge of 'new-fangled' superluminal apocrypha and their relation to Quantum Theory. The book is based on a course on Special Relativity and acclaimed by students taught by Dragan who is a leader of a research group on Relativistic Quantum Information theory at the University of Warsaw and the National University of Singapore.Scan the QR code to access the author's collection of Youtube videos that explain the fundamental concepts of physics described in Unusually Special Relativity.

"If a child wants proof, we can think of 10 different ways to show that we are surrounded by air, but we are, of course, normally unaware that we live at the bottom of an 'ocean" of air. It is claimed, in this book, that we are unaware, similarly, that we are surrounded by an atmosphere of aether. There is one major difference, however: We have not been able to detect the aether.Nevertheless, the aether provides a solution to the following mystery: How can light, or any electromagnetic wave, travel for billions of years across the vastness of the Universe, without losing any energy? The answer is that the Universe is filled with a light-transmitting medium, The Aether. The proof that there is an aether is the subject of the present book."

The wealth of recent cosmic microwave background and large-scale structure data has transformed the field of cosmology. These observations have not only become precise enough to answer questions about the universe on the largest scales, but also to address puzzles in the microscopic description of Nature. This thesis investigates new ways of probing the early universe, the properties of neutrinos and the possible existence of other light particles. In particular, based on detailed theoretical insights and novel analyses, new evidence for the cosmic neutrino background is found in the distribution of galaxies and in cosmic microwave background data. This tests the Standard Model of particle physics and the universe back to a time when it was about one second old. Furthermore, it is demonstrated that future observations will be capable of probing physics beyond the Standard Model since they can achieve a particular target which would either allow the detection of any light particles that have ever been in thermal equilibrium or imply strong bounds on their properties.

The ultimate proofs that black holes exist have been obtained very recently thanks to the detection of gravitational waves from their coalescence and due to material orbiting at a distance of some gravitational radii imaged by optical interferometry or X-ray reverberation mapping. This book provides three comprehensive and up-to-date reviews covering the gravitational wave breakthrough, our understanding of accretion and feedback in supermassive black holes and the relevance of black holes for the Universe since the Big Bang. Neil J. Cornish presents gravitational wave emission from black hole mergers and the physics of detection. Andrew King reviews the physics of accretion on to supermassive black holes and their feedback on host galaxies. Tiziana Di Matteo addresses our understanding of black hole formation at cosmic dawn, the emergence of the first quasars, black hole merging and structure formation. The topics covered by the 48th Saas-Fee Course provide a broad overview of the importance of black holes in modern astrophysics.

This textbook is designed to serve as a link between the basic disciplines of physics and the frontier topics within high energy astrophysics, aiming at a level of difficulty congruent with that of other physics topics studied at undergraduate level. Therefore, this preparatory and introductory text serves as a gateway to a more detailed study of many of the most interesting and complex phenomena being investigated by contemporary astrophysics. Among others, these include: the evolution of stars, supernovae, neutron stars, black holes, solar neutrinos, and - importantly - the exciting new field of gravitational wave astronomy. The book is supplemented by a collection of problems with which students can test their understanding of the material presented.

This book consolidates the latest research on the Hadean Eon - the first 500 million years of Earth history - which has permitted hypotheses of early Earth evolution to be tested, including geophysical models that include the possibility of plate tectonic-like behavior. These new observations challenge the longstanding Hadean paradigm - based on no observational evidence - of a desiccated, lifeless, continent-free wasteland in which surface petrogenesis was largely due to extraterrestrial impacts. The eon was termed "Hadean" to reflect such a hellish environment. That view began to be challenged in 2001 as results of geochemical analyses of greater than 4 billion year old zircons from Australia emerged. These data were consistent with the zircons forming in a world much more similar to today than long thought and interpreted to indicate that sediment cycling was occurring in the presence of liquid water. This new view leaves open the possibility that life could have emerged shortly after Earth accretion. The epistemic limitations under which the old paradigm persisted are closely examined. The book is principally designed as a monograph but has the potential to be used as a text for advanced graduate courses on early Earth evolution.