| Affiliation: | (1) TH Division, Physics Department, CERN, CH-1211 Geneva 23, Switzerland;(2) Theoretical Physics, Physics Department, King's College London, Strand, WC2R 2LS, UK;(3) George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A&M University, College Station, TX 77843, USA;(4) Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, TX 77381, USA;(5) Academy of Athens, Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens, 10679, Greece |
| Abstract: | Generic cosmological models in non-critical string theory have a time-dependent dilaton background at a late epoch. The cosmological deceleration parameter q 0 is given by the square of the string coupling, g s 2, up to a negative sign. Hence the expansion of the Universe must accelerate eventually, and the observed value of q 0 corresponds to g s 2 ∼ 0.6. In this scenario, the string coupling is asymptotically free at large times, but its present rate of change is imperceptibly small. First Award in the 2005 Essay Competition of the Gravity Research Foundation. - Ed. |
