1,721,144 research outputs found
From pre- to post-big bang: an (almost) self-dual cosmological history
Full text linkWe present a short introduction to a non-standard cosmological scenario
motivated by the duality symmetries of string theory, in which the big bang
singularity is replaced with a "big bounce" at high but finite curvature. The
bouncing epoch is prepared by a long (possibly infinitely extended) phase of
cosmic evolution, starting from an initial state asymptotically approaching the
string perturbative vacuum.Comment: This paper is dedicated to the memory of John D. Barro
Il fondo di radiazione gravitazionale fossile
No full textProprieta' del fondo cosmico di radiazione gravitazionale di orgine primordial
L’anisotropia della radiazione cosmica
No full textProprieta' del fondo cosmico di radiazione elettromagnetica
On the localization of seismic events
No full textSource location of seismic events is a cruciial item in seismology. Different methods of source location are considered and discussed, with particular emphasis on the determination of the azimuth and the angle of emergence of the first recorded impulse, which requires that all of the three components of ground displacement are measured at the seismometic station. The greatly increased accuracy and sensitivity of the present instrumentation and the possibility of digital recording of seismic data ask for reconsideration of the azimuth-angle-of-emergence method, especially for the location of seismic events on a regional scale
La geometria di Friedmann-Robertson-Walker
No full textProprieta' della metrica di Friedman-Lemaitre-Robertson-Walke
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