Superluminal Recession Velocities

Hubble's Law, v=HD (recession velocity is proportional to distance), is a theoretical result derived from the Friedmann-Robertson-Walker metric. v=HD applies at least as far as the particle horizon and in principle for all distances. Thus, galaxies with distances greater than D=c/H are receding from us with velocities greater than the speed of light and superluminal recession is a fundamental part of the general relativistic description of the expanding universe. This apparent contradiction of special relativity (SR) is often mistakenly remedied by converting redshift to velocity using SR. Here we show that galaxies with recession velocities faster than the speed of light are observable and that in all viable cosmological models, galaxies above a redshift of three are receding superluminally.Comment: 4 pages, 2 figures, Cosmology and Particle Physics 2000 Conference Proceedings; reference adde

La durée d’existence des coentreprises internationales : une revue de la littérature

National audienceJoint ventures represent one of the main forms of internationalization, but they are unstable and risky. The objective of this paper is to contribute to a better understanding of the life-span of these organizations. We examine fifteen empirical studies published in international business journals in order to explain the main measures used to analyze the instability, survival and longevity of international joint ventures. Our findings provide a panorama of existing research on this topic.Les coentreprises (joint ventures) constituent l’une des principales formes d’internationalisation, mais elles sont instables et risquées. L’objectif de cet article est de contribuer à une meilleure connaissance de la durée d’existence de ces organisations. Nous examinons quinze études empiriques publiées dans les revues de management international afin d’expliquer les principales mesures utilisées pour analyser l’instabilité, la survie et la longévité des coentreprises internationales. Les résultats permettent de donner un panorama de la recherche sur cette thématique