After about a century of success, physicists feel the need to probe the limits of validity of special-relativity base theories. This book is the outcome of a special seminar held on this topic. The authors gather in a single volume an extensive collection of introductions and reviews of the various facets involved, and also includes detailed discussion of philosophical and historical aspects.

17 readable articles give a thorough and self-contained overview of recent developments in relativistic gravity research. The subjects covered are: gravitational lensing, the general relativistic n-body problem, observable effects in the solar system, gravitational waves and their interferometric detection, very-long-baseline interferometry, international atomic time, lunar laser- ranging measurements, measurement ofthe gravitomagnetic field of the Earth, fermion and boson stars and black holes with hair, rapidly rotating neutron stars, matter wave interferometry, and the laboratory test of Newton's law of gravity.Any scientist interested in experimentally or observatio- nally oriented relativistic gravity will read the book with profit. In addition, it is perfectly suited as a complementary text for courses on general relativity and relativistic astrophysics.

The search for a quantum gravity theory, a theory expected to combine the principles of general relativity and quantum theory, has led to some of the most deepest and most difficult conceptual and mathematical questions of modern physics. The present book, addressing these issues in the framework of recent versions of canonical quantization, is the first to present coherently the background for their understanding. Starting with an analysis of the structure of constrained systems and the problems of their quantization, it discusses the canonical formulation of classical relativity from different perspectives and leads to recent applications of canonical methods to create a quantum theory of gravity. The book aims to make accessible the most fundamental problems and to stimulate work in this field.

The theory, observations, and applications ofgravitational lensingconstitute one ofthe most rapidly growing branches ofextragalactic astrophysics. The deflection of light from very distant sources by intervening masses provides a unique possibility for the investigation of both background sources and lens mass distributions. Gravitational lensing manifestsitselfmost distinctly through multiply imaged QSOs and the formation of highly elongated im ages of distant galaxies ('arcs') and spectacular ring-like images of extra galactic radio sources. But the effects of gravitational light deflection are not limited to these prominent image configurations; more subtle, since not directly observable, consequences of lensing are the, possibly strong, mag nification of sources, which may permit observation of intrinsically fainter, or more distant, sources than would be visible without these natural tele scopes. Such light deflection can also affect the source counts of QSOs and of other compact extragalactic sources, and can lead to flux variability of sources owing to propagation effects. Trying to summarizethe theory and observationalstatus ofgravitational lensing in a monograph turned out to be a bigger problem than any of the authors anticipated when we started this project at the end of 1987, encour aged by Martin Harwit, who originally approached us. The development in the field has been very rapid during the last four years, both through the ory and through observation, and many sections have been rewritten several times, as the previous versions became out of date.

After about a century of success, physicists feel the need to probe the limits of validity of special-relativity base theories. This book is the outcome of a special seminar held on this topic. The authors gather in a single volume an extensive collection of introductions and reviews of the various facets involved, and also includes detailed discussion of philosophical and historical aspects.

Nothing new from the Ice Age? Far from it! Barely ten years have passed since the first edition of this book was published, but in that time researchers around the world have developed new methods and published their findings in scientific journals. Consequently, ideas about the course of the Ice Age have changed dramatically. The sequence of the individual ice advances, the direction of ice movement and the direction of meltwater drainage are only partially known, but they can be reconstructed. This book offers in-depth information about the state of the investigations. Ice ages are the periods of the earth's history in which at least one polar region is glaciated or covered by sea ice. Thus, we are currently living in an Ice Age. The present Ice Age is also the period in which humans started to intervene in the shaping of the earth. The results are obvious. Aerial and satellite images can be used to trace the melting of glaciers, but also the decay of the Arctic permafrost, and the clearing of the Brazilian rainforest. This book is a translation of the original German 2nd edition Das Eiszeitalter by Juergen Ehlers, published by Springer-Verlag GmbH Germany, part of Springer Nature, in 2020. The translation was done with the help of artificial intelligence (machine translation by DeepL.com). A subsequent human revision was done primarily in terms of content, so that the book will read stylistically differently from a conventional translation. Springer Nature works continuously to further the development of tools for the production of books and promotes technologies to support the authors.

Dieses Buch ist bis heute eine der popularsten Darstellungen der Relativitatstheorie geblieben. In der vorliegenden Version haben J. Ehlers und M. Poessel vom Max-Planck-Institut fur Gravitationsphysik (Albert-Einstein-Institut) in Golm/Potsdam den Bornschen Text kommentiert und einen den anschaulichen, aber prazisen Stil Borns wahrendes, umfangreiches Erganzungskapitel hinzugefugt, das die sturmische Entwicklung der Relativiatatstheorie bis hin zu unseren Tagen nachzeichnet. Eingegangen wird auf Gravitationswellen und Schwarze Loecher, auf neuere Entwicklungen der Kosmologie, auf Ansatze zu einer Theorie der Quantengravitation und auf die zahlreichen raffinierten Experimente, welche die Gultigkeit der Einsteinschen Theorie mit immer groesserer Genauigkeit bestatigt haben. Damit bleibt dieses Buch nach wie vor einer der unmittelbarsten Zugange zur Relativitatstheorie fur alle die sich fur eine uber das rein popularwissenschaftliche hinausgehende Einfuhrung interessieren.

Aus dem Vorwort von Jurgen Ehlers zur 7. Auflage: "Die ... Entwicklung der Physik macht verstandlich, warum ein so "altes" Werk wie Raum, Zeit, Materie noch aktuell ist: Die Riemann-Einsteinsche Raumzeitstruktur, die von Weyl so meisterhaft beschrieben und aus ihren mathematischen und physikalischen Wurzeln hervorwachsend dargestellt wird, ist immer noch die physikalisch umfassendste und erfolgreichste Raumzeittheorie, die bisher entwickelt und mit der Erfahrung konfrontiert wurde. (...) Als erstes Lehrbuch der noch neuen Theorie setzt es sich grundlicher als spatere Bucher mit den historischen Wurzeln und den sachlichen Motiven auseinander, die zur Einfuhrung der damals neuen Begriffe wie Zusammenhang und Krummung in die Physik gefuhrt haben. Zweitens ist es von dem vielleicht letzten Universalisten geschrieben worden, der alle wesentlichen Entwicklungen der Mathematik und Physik seiner Zeit nicht nur uberblickte, sondern in wesentlichen Teilen mitgestaltete. Das Studium dieses Werkes vermittelt nicht nur die Grundzuge der beiden Relativitatstheorien, sondern zeigt Zusammenhange mit anderen Ideen, nicht zuletzt auch der Naturphilosophie auf.""

Dieses Buch ist bis heute eine der popularsten Darstellungen der Relativitatstheorie geblieben. In der vorliegenden Version haben J. Ehlers und M. Poessel vom Max-Planck-Institut fur Gravitationsphysik (Albert-Einstein-Institut) in Golm/Potsdam den Bornschen Text kommentiert und einen den anschaulichen, aber prazisen Stil Borns wahrendes, umfangreiches Erganzungskapitel hinzugefugt, das die sturmische Entwicklung der Relativiatatstheorie bis hin zu unseren Tagen nachzeichnet. Eingegangen wird auf Gravitationswellen und Schwarze Loecher, auf neuere Entwicklungen der Kosmologie, auf Ansatze zu einer Theorie der Quantengravitation und auf die zahlreichen raffinierten Experimente, welche die Gultigkeit der Einsteinschen Theorie mit immer groesserer Genauigkeit bestatigt haben. Damit bleibt dieses Buch nach wie vor einer der unmittelbarsten Zugange zur Relativitatstheorie fur alle die sich fur eine uber das rein popularwissenschaftliche hinausgehende Einfuhrung interessieren.

Das Studium von Hermann Weyls "Raum . Zeit . Materie" ist auch heute noch lohnenswert. Als erste systematische Gesamtdarstellung der speziellen und allgemeinen Relativitatstheorie einschliesslich der zugehorigen Mathematik setzt es sich grundlich mit den historischen Wurzeln auseinander. Die Betonung des Begriffs des linearen Zusammenhangs unabhangig von der Metrik kommt der heutigen Auffassung und den Verallgemeinerungen in den Eichtheorien entgegen. Fur ein grundliches Verstandnis der modernen Eichtheorie ist Weyls Buch immer noch eine wichtige Grundlage."

The Wadden Sea area of the North Sea is one which undergoes rapid morphological changes. Under natural conditions, the barrier islands would adjust themselves to a rising sea level. However, because the islands are densely populated and have an important role as holiday resorts, morphological changes are undesirable. Coastal engineering counter-measures have been undertaken to prevent beach erosion, shifting of tidal inlets, breaching of dune ridges and landward-directed washover. The natural processes and the results of human interference including the negative consequences of many of the measures are discussed in detail. The author presents the current state of research, together with the results of his own investigations. In addition, a comprehensive description of the geomorphological development and recent problems of the barrier islands from Texel to Fano is given for the first time. The book includes 40 colour photographs and 393 figures, almost all previously unpublished. Satellite and radar imagery as well as many aerial photographs are also included. The book is intended for geomorphologists, sedimentologists, environmentalists and all those with a scientific interest in tidal flats and barrier islands.