The fundamental constants and their variation: observational status and theoretical motivations

This article describes the various experimental bounds on the variation of the fundamental constants of nature. After a discussion on the role of fundamental constants, of their definition and link with metrology, the various constraints on the variation of the fine structure constant, the gravitational, weak and strong interactions couplings and the electron to proton mass ratio are reviewed. This review aims (1) to provide the basics of each measurement, (2) to show as clearly as possible why it constrains a given constant and (3) to point out the underlying hypotheses. Such an investigation is of importance to compare the different results, particularly in view of understanding the recent claims of the detections of a variation of the fine structure constant and of the electron to proton mass ratio in quasar absorption spectra. The theoretical models leading to the prediction of such variation are also reviewed, including Kaluza-Klein theories, string theories and other alternative theories and cosmological implications of these results are discussed. The links with the tests of general relativity are emphasized.Comment: 56 pages, l7 figures, submitted to Rev. Mod. Phy

Dynamic Publication Formats and Collaborative Authoring

While Online Publishing has replaced most traditional printed journals in less than twenty years, today’s Online Publication Formats are still closely bound to the medium of paper. Collaboration is mostly hidden from the readership, and ‘final’ versions of papers are stored in ‘publisher PDF’ files mimicking print. Meanwhile new media formats originating from the web itself bring us new modes of transparent collaboration, feedback, continued refinement, and reusability of (scholarly) works: Wikis, Blogs and Code Repositories, to name a few. This chapter characterizes the potentials of Dynamic Publication Formats and analyzes necessary prerequisites. Selected tools specific to the aims, stages, and functions of Scholarly Publishing are presented. Furthermore, this chapter points out early examples of usage and further development from the field. In doing so, Dynamic Publication Formats are described as (a) a ‘parallel universe’ based on the commodification of (scholarly) media, and (b) as a much needed complement, slowly recognized and incrementally integrated into more efficient and dynamic workflows of production, improvement, and dissemination of scholarly knowledge in general