The fundamental constants in physics and their possible time variation

We discuss the fundamental constants of physics within the Standard Model of particle physics. In this model there are 28 fundamental constants, e.g. the constant of gravity or the fine structure constant. First we discuss these fundamental constants. Later we consider possible changes of these constants on the cosmological time scale. The time constraints for the fundamental parameters, related to unstable quarks or leptons, are not very strong. The Grand Unification of the observed strong, electromagnetic and weak interactions implies relations between time variation of the fine structure constant α and the QCD scale Λc. The astrophysical observation of a variation of α implies a time variation of Λc of the order of at least 10−15 /year. An experiment in Quantum Optics, which was designed to look for a time variation of Λc, is discussed. An astrophysics experiment indicates a time variation of the ratio of the proton mass and the electron mass.