The expansion of the universe on short distance scales is a new frontier to investigate dark energy. excess orbital decay in binary pulsars may be related acceleration by local cosmic expansion, called drag. Modern observations two independent binaries (PSR B1534+12 and PSR B1913+16) support this interpretation result scale-independent with viscous uniformity, which systems have smaller rate th...

An overview is given in section 1, of uncertain building blocks of present-day cosmologies. Thereafter, these edited lecture notes deal with the following four special problems: (1) They advertise Wiltshire’s result – making ‘dark energy’ obsolete – that accelerated cosmic expansion may be an artefact, due to an incorrect evaluation of the cosmic timescale in a Universe whose bulk matter is inh...

Recent detections of the Integrated Sachs-Wolfe effect through the correlation of the cosmic microwave background temperature anisotropy with traces of large scale structure provided independent evidence for the expansion of the universe being dominated by something other than matter. Even with perfect data, statistical errors will limit the accuracy of such measurements to worse than 10%. On t...

There is now overwhelming observational evidence that our Universe is accelerating in its expansion. I discuss how modified gravitational models can provide an explanation for this observed late-time cosmic acceleration. We consider specific lowcurvature corrections to the Einstein-Hilbert action. Many of these models generically contain unstable de Sitter solutions and, depending on the parame...

Using the usual definitions of information and entropy in quantum gravity and statistical mechanics and the existing views about the relation between information and complexity, we examine the evolution of complexity in an ever expanding universe.

We present new determinations of the cosmic expansion history from red-envelope galaxies. We have obtained for this purpose high-quality spectra with the Keck-LRIS spectrograph of red-envelope galaxies in 24 galaxy clusters in the redshift range 0.2 < z < 1.0. We complement these Keck spectra with high-quality, publicly available archival spectra from the SPICES and VVDS surveys. We improve ove...