Prof. Raúl Jiménez (Madrid, 1967) obtained his PhD at the Niels Bohr Institute in 1995; he then moved to the Royal Observatory in Edinburgh were he held a PPARC Advanced Fellowship. After this, he moved to the US where he joined the faculty, as a professor, of the Physics & Astronomy departments of Rutgers University and the University of Pennsylvania. He joined ICREA in September 2007 as Research Professor at the Institute of Cosmos Sciences. He has made several contributions to our understanding of the Universe: the first evidence of dark energy from the ages of high redshift galaxies and globular clusters, the origin of dark galaxies, the first evidence of how galaxies are assembled as a function of cosmic time, the first determination of the expansion history of the Universe, the role of cosmic explosions in the survival of exolife, the role of symmetries in the early universe and a lower bound to the value of the cosmological constant.