Baryon asymmetry

In physical cosmology, the baryon asymmetry problem, also known as the matter asymmetry problem or the matter–antimatter asymmetry problem, is the observed imbalance in baryonic matter and antibaryonic matter in the observable universe. As the two form and behave in nearly identical ways, it is expected that they would have been created in near equal portions by the Big Bang, but, in reality, matter makes up the vast majority of the universe. Neither the Standard Model of particle physics nor the theory of general relativity provides an explanation for why this should be so. It is likely some physical laws must have acted differently in the very early universe and the minimum set of differences were proposed by Andrei Sakharov in 1967. Several competing hypotheses exist to explain the imbalance of matter and antimatter that resulted in baryogenesis. However, there is, so far, no consensus theory to explain the phenomenon, which has been described as "one of the great mysteries in physics".