Quantizing gravity and spacetime: Where do we stand ?

We review five possible solutions to the riddle posed by Quantum Gravity: (1) Gravity should stay as a classical theory (L. Rosenfeld); (2) Quantum Gravity requires a formalism which will take the human mind (or the intelligent observer) into account, resolving at the same time the riddle of the collapse of the wave function/state vector in Quantum Mechanics in general (Penrose); (3) Perturbative Quantization; (4) Hamiltonian Quantization (Dirac, Ashtekar); (5) String Theory. We also discuss the quantization of spacetime.     

Scientometric analysis of physics (1979–2008): A quantitative description of scientific impact

Citations are a way to show how researchers build on existing research to further evolve research.The citation count is an indication of the influence of specific articles.The importance of citations means that it is valuable to analyze the articles that are cited the most.This research investigates highly-cited articles in physics (1979-2008) using citation data from the ISI Web of Science.In this study,1544205 articles were examined.The objective of the analysis was to identify and list the highly-product...     

Mathematics and turbulence: where do we stand?

This contribution covers the topics presented by the authors at the “Fundamental Problems of Turbulence, 50 Years after the Marseille Conference 1961” meeting that took place in Marseille in 2011. It focuses on some of the mathematical approaches to fluid dynamics and turbulence. This contribution does not pretend to cover or answer, as the reader may discover, the fundamental questions in turbulence, however, it aims toward presenting some of the most recent advances in attacking these questions using rigorous mathematical tools. Moreover, we consider that the proofs of the mathematical statements (concerning, for instance, finite time regularity, weak solutions and vanishing viscosity) may contain information as relevant, to the understanding of the underlying problem, as the statements themselves.     

Laser physics—20-year jubilee

From the Editorial Board

Laser physics—20-year jubilee     

Precocious signs of new physics: Are we eight now?

Although the CKM-paradigm seems to work to an accuracy of about 15–20%, we emphasize that there are by now several indications that suggest the need for a beyond the Standard Model CP-odd phase. The value of sin 2β measured via the goldplated (tree) mode, B → ψK _s is smaller than the value deduced by using improved lattice matrix elements. The value of sin 2β measured via ‘penguin-dominated’ (loop) decays tends to be even smaller still. There is also a rather large difference between the direct CP asymmetries in → K ⁻ π ⁺ and B ⁻ → K ⁻ π ⁰ that is rather difficult to understand. More recently, CDF and D0 are finding about a 2σ signal in CP asymmetry in the corresponding gold-plated mode B _s → ψϕ. If true, this would be consistent with the indications of new CP-phase in penguin b → s transitions seen at B-factories. After describing these possible signs of trouble for the SM-CKM paradigm, we give a brief discussion of some of the BSM scenarios that could be the underlying cause of these deviations. In particular, we find that the data are quite suggestive of a fourth family with m′ _t in the range of 400–600 GeV as perhaps the simplest BSM candidate which ‘naturally’ explains the data.      

Reading the patterns in living cells —the physics of ca2+ signaling

Ca²⁺ is one of the most important messengers. It transmits signals inside living cells and takes part in intercellular coordination. The dynamics of the Ca²⁺ concentration shows a transition from elemental, stochastic events to global events like waves and oscillations. This transition renders it an ideal tool for studying basic concepts of pattern formation, especially since access to the most important experimental parameters is given. Ca²⁺ dynamics in living cells has been a major topic of biophysical modelling in the last 15 years. Modelling has reached the level of predictive power. The theoretical analysis of waves provided new insight into the mechanisms of Ca²⁺ signaling and led to new concepts of analysis of wave equations with concentration dependent diffusion and novel wave bifurcations. Modelling of oscillations provided understanding especially of complex oscillations and allowed to extract information about the underlying cellular parameters and mechanisms. The investigation of the stochastic aspects of intracellular Ca²⁺ dynamics demonstrated the fundamental role of fluctuations arising from the control of the release channel by Ca²⁺ and IP₃. This review presents an overview of current theoretical research on Ca²⁺ dynamics in living cells driven by the inositol 1,4,5-trisphosphate receptor channel.     

Software Process Improvement in CMS—Are we Different？

One of the most challenging issues faced in HEP in recent years is the question of how to capitalise on software development and maintenance experience in a continuous manner.To capitalise inour context means to evaluate and apply new technologies as they arise,and to further evolve technologies arlready widely in use,It also implies the definition and adoption of standards,while ensuring reproducibility and quality of results.The CMS process improvement effort is two-pronged.It aims at continuous improve ment of the ways we do Object Oriented software,as well as continuous improvement in the efficiency of the working enviuronment.In particular the use and creation of de-facto software process standards within CMS has proven to be key to our successful software process improvement program.We describe the successful CMS implementation of a software process improvement strategy,following ISO 15504 since three years.We give the current status of the most important processes families formally established in CMS,and provide the guidelines we followed both for tool development,and methodology establishment.     

Historic papers in physics — The case of Hugo Martin Tetrode, 1895–1931

Conclusions It appears from the foregoing discussion that the results of citation analysis can be interpreted, in the investigated case, as indicators for either the direct use which is made of a paper in research, or for the visibility of its author as a pioneer in a (sub)-discipline. In the last case the citation scores primarily reflect the dynamics of the relevant scientific discipline.More generally the case-study indicates the potential usefulness of combining citation analysis with more conventional ways of evaluating the role articles play and have played in science.The authors wish to thank Prof. H. B. G. Casimir who first brought the work of H. M. Tetrode the their attention.     

Universal Teichmüller space in geometry and physics

Lipman Bers' universal Teichmüller space, classically denoted by T(1), plays a significant role in Teichmüller theory, because all the Teichmüller spaces T(G) of Fuchsian groups G can be embedded into it as complex submanifolds. Recently, T(1) has also become an object of intensive study in physics, because it is a promising geometric environment for a non-perturbative version of bosonic string theory. We provide a non-technical survey of what is currently known about the geometry of T(1) and what is conjectured about its physical meaning. Our bibliography should be rather comprehensive, but we apologize for any unjustified omissions.     

Conformal space-times—The arenas of physics and cosmology

The mathematical and physical aspects of the conformal symmetry of space-time and of physical laws are analyzed. In particular, the group classification of conformally flat space-times, the conformal compactifications of space-time, and the problem of imbedding of the flat space-time in global four-dimensional curved spaces with non-trivial topological and geometrical structure are discussed in detail. The wave equations on the compactified space-times are analyzed also, and the set of their elementary solutions constructed. Finally, the implications of global compactified space-times for cosmology are discussed. It is argued that the recent discovery of periodic structure of matter distribution on large distances strongly suggests that the global cosmological space-time should be close. Next we analyze the inflation scalar field in the inflationary model of universe evolution considered on the spatially compact Robertson-Walker space-time. It is shown that the energy distribution in this model is periodic and the periods and density decrease with increasing distance, in striking agreement with experimental data. Our model of the universe also provides a definite predictions for the energy distribution, polar and azimuthal, considered as a function of angles and . These predictions should be tested with the new astronomical data.Dedicated to Professor Constantin Piron on the occasion of his sixtieth birthday, June 11, 1992.This publication is based on work sponsored by the US-Czechoslovakia Science and Technological Joint Fund under Project Number 92067 and by Grant ASCR under Project Number 19085.Partially supported by the Stiftung Für Deutsch-Polnische Zusammenarbeit Grant No. 984/94/LN.     

Accelerator neutrino physics—Current status and future prospects

This review article describes the current status and future prospects of accelerator neutrino physics. The emphasis is on recent developments in the oscillation physics area but there is also a limited discussion about the status of neutrino cross sections. The approach taken is pedagogical and an effort is made to explain the basic techniques used in the accelerator studies of neutrino physics.     

Soliton physics with semiconductor exciton–polaritons in confined systems

In the past decade, there has been a significant progress in the study of non-linear polariton phenomena in semiconductor microcavities. One of the key features of non-linear systems is the emergence of solitons. The complexity and the inherently strong nonlinearity of the polariton system made it a perfect sandpit for observing solitonic effects in half-light half-matter environment. This review focuses on the theory and the latest experimental elucidating physics as well as potential applications of conservative and dissipative solitons in exciton–polariton systems.