http://arxiv.org/abs/1401.5313 Hot big bang or slow freeze? C.Wetterich (Submitted on 21 Jan 2014) We confront the hot big bang for the beginning of the universe with an equivalent picture of a slow freeze - a very cold and slowly evolving universe. In the slow freeze picture the masses of elementary particles increase and the gravitational constant decreases with cosmic time, while the Newtonian attraction remains unchanged. The slow freeze and hot big bang pictures both describe the same observations or physical reality. We present a simple three-parameter "crossover model" without a "big bang singularity". In the infinite past space-time is flat. Our model is compatible with all present observations, describing the generation of primordial density fluctuations during inflation as well as the present transition to a dark energy dominated universe.