CONTENTS Ann. Phys. (Berlin) 17, No. 9–10, 613 – 615 (2008) / DOI 10.1002/andp.200817013 Full text on our homepage at www.ann-phys.org EDITORIAL Page 617 Friedrich W. Hehl Preface ORIGINAL PAPERS HISTORY RELATED Page 619 – 630 Thibault Damour What is missing from Minkowski’s “Raum und Zeit” lecture This contribution tries to highlight the importance of Minkowski’s “Raum und Zeit” lecture in a “negative” way, where negative is taken in the photographic sense of reversing lights and shades. Indeed, we focus on the “shades” of Minkowski’s text, i.e. what is missing, or misunderstood. In particular, the article focuses on two issues: (i) why are Poincaré’s pioneering contributions to four-dimensional geometry not quoted by Minkowski (while he abundantly quoted them a few months before the Cologne lecture)?, and (ii) did Minkowski fully grasp the physical (and existential) meaning of “time” within spacetime? Page 631 – 690 H. A. Kastrup On the advancements of conformal transformations and their associated symmetries in geometry and theoretical physics ζ The historical developments of conformal transformations and symmetries are sketched: Their origin from stereographic projections of the globe, their blossoming in two dimensions within the ﬁeld of analytic complex functions, the generic role of transformations by reciprocal radii in dimensions higher than two and their linearization in terms of polyspherical coordinates by Darboux, Weyl’s attempt to extend General Relativity, the slow rise of ﬁnite dimensional conformal transformations in classical ﬁeld theories and the problem of their interpretation, then since about 1970 the rapid spread of their acceptance for asymptotic and structural problems in quantum ﬁeld theories and beyond, up to the current AdS/CFT conjecture. N a β P (ξ,η,ζ ) φ S x,ξ y,η P̂ (x,y ) © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 614 Page 691 – 704 Contents Friedrich W. Hehl Maxwell’s equations in Minkowski’s world: their premetric generalization and the electromagnetic energy-momentum tensor In December 1907, Minkowski expressed the Maxwell equations in the very beautiful and compact 4-dimensional form: lor f = −s, lor F ∗ = 0. Here ‘lor’, an abbreviation of Lorentz, represents the 4-dimensional differential operator. The Minkowski’s derivation is studied and it is shown how these equations generalize to their modern premetric form. It is discussed how Minkowski arrived at it and how its premetric formulation looks like. NEW FRONTIERS Page 705 – 727 Bahram Mashhoon Nonlocal special relativity In the special theory of relativity, Lorentz invariance is extended in Minkowski spacetime from ideal inertial observers to actual observers by means of the hypothesis of locality, which postulates that accelerated observers are always pointwise inertial. A critical examination reveals its domain of validity: it is true for pointwise coincidences, but is in conﬂict with wave-particle duality. To remedy this situation, a nonlocal theory of accelerated systems is presented that reduces to the standard theory in the limit of small accelerations. Page 728 – 768 Sergio Cacciatori, Vittorio Gorini, and Alexander Kamenshchik Special relativity in the 21st century This paper rests on the idea that the basic observed symmetries of spacetime homogeneity and of isotropy of space lead to a formulation of special relativity based on the appearance of two universal constants: a limiting speed c and a cosmological constant Λ. That these constants should exist is an outcome of the underlying symmetries and is conﬁrmed by experiments and observations, which furnish their actual values. On this basis, main aspects of the theory of special relativity based on SO(1, 4) (de Sitter relativity) are developed. Page 769 – 786 Y. Itin and Y. Friedman Backwards on Minkowski’s road. From 4D to 3D Maxwellian electromagnetism Minkowski’s concept of a four-dimensional physical space is a central paradigm of modern physics. Is the (1+3) decomposition of the covariant four-dimensional form unique? How do the different sign assumptions of electrodynamics emerge from this decomposition? Which of these assumptions are fundamental and which of them may be modiﬁed? How does the Minkowski space-time metric emerge from this preliminary metric-free construction? This paper looks for answers to the problems mentioned. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ann-phys.org Ann. Phys. (Berlin) 17, No. 9–10 (2008) Page 787 – 802 615 Ari Sihvola and Ismo V. Lindell Perfect electromagnetic conductor medium This article presents a review of a novel concept in electromagnetics, the Perfect Electromagnetic M >0 β Conductor (PEMC). In the Minkowskian represenPEMC tation of the material response to electromagnetic ﬁelds, PEMC corresponds to the axion part of the reﬂected incident constitutive tensor. From the electrical engineering point of view, PEMC is a generalization of the perfect electric conductor (PEC) and perfect magnetic conductor (PMC) materials which are useful concepts as ideal boundaries in the modeling of electromagnetic problems. This paper discusses how the PECM medium generalizes earlier known electromagnetic problems. “CLASSICAL” SUBJECTS Page 803 – 829 Florian Loebbert The Weinberg-Witten theorem on massless particles: an essay This essay deals with the Weinberg-Witten theorem which imposes limitations on massless particles. First, a classiﬁcation of massless particles given by the Poincaré group as the symmetry group of Minkowski spacetime is motivated. Then the fundamental structure of the background in the form of Poincaré covariance is used to derive restrictions on charged massless particles known as the WeinbergWitten theorem. Possible misunderstandings in the proof of this theorem are addressed, and the consequences of the theorem are discussed. matrix elements between massless one particle states p , ±j|J μ |p, ±j or p , ±j|T μν |p, ±j 1 2 • physical measurement • Poincar´e covariance • non-vanishing charges = 0 Lorentz rotation of • particle states |p, ±j • currents J μ or T μν = 0 for j > 1 2 or j > 1 contradiction Page 830 – 851 Yuri N. Obukhov Electromagnetic energy and momentum in moving media The problem of the electromagnetic energy-momentum tensor is among the oldest and the most controversial in macroscopic electrodynamics. In the center of the issue is a dispute about the Minkowski and the Abraham tensors for moving media. An overview of the current situation is presented. Annalen der Physik is indexed in Chemical Abstracts Service/SciFinder, COMPENDEX, Current Contents® /Physical, Chemical & Earth Sciences, FIZ Karlsruhe Databases, INIS: International Nuclear Information System Database, INSPEC, Journal Citation Reports/Science Edition, Science Citation Index Expanded™, Science Citation Index® , SCOPUS, Statistical Theory & Method Abstracts, VINITI, Web of Science® , Zentralblatt MATH/Mathematics Abstracts Recognized by the European Physical Socity www.ann-phys.org © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

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