We report a detection of the baryon acoustic oscillation feature in the three-dimensional correlation function of the transmitted flux fraction in the Lya forest of high-redshift quasars. The study uses 48 640 quasars in the redshift range 2.1 = z = 3.5 from the Baryon Oscillation Spectroscopic Survey of the third generation of the Sloan Digital Sky Survey. At a mean redshift z = 2.3, we measure the monopole and quadrupole components of the correlation function for separations in the range (...) 20 h-1 Mpc < r < 200 h-1 Mpc. A peak in the correlation function is seen at a separation equal to times the distance expected for the BAO peak within a concordance.CDM cosmology. This first detection of the BAO peak at high redshift, when the universe was strongly matter dominated, results in constraints on the angular diameter distance DA and the expansion rate H at z = 2.3 that, combined with priors on H0 and the baryon density, require the existence of dark energy. Combined with constraints derived from cosmic microwave background observations, this result implies H = km s-1 Mpc-1, indicating that the time derivative of the cosmological scale parameter.a = H/ is significantly greater than that measured with BAO at z ∼ 0.5. This demonstrates that the expansion was decelerating in the range 0.7 < z < 2.3, as expected from the matter domination during this epoch. Combined with measurements of H0, one sees the pattern of deceleration followed by acceleration characteristic of a dark-energy dominated universe. © 2013 ESO. (shrink)

What can fashionable ideas, blind faith, or pure fantasy possibly have to do with the scientific quest to understand the universe? Surely, theoretical physicists are immune to mere trends, dogmatic beliefs, or flights of fancy? In fact, acclaimed physicist and best-selling author Roger Penrose argues that researchers working at the extreme frontiers of physics are just as susceptible to these forces as anyone else. In this provocative book, he argues that fashion, faith, and fantasy, while sometimes productive and even essential (...) in physics, may be leading today's researchers astray in three of the field's most important areas--string theory, quantum mechanics, and cosmology... The result is an important critique of some of the most significant developments in physics today from one of its most eminent figures."--Jacket. (shrink)