This lecture covers experiments related to relativistic kinematics, including the detection of mu-mesons at the Polytechnic University and the Doppler shift phenomenon. It discusses the detection of muons on Earth's surface, the longitudinal Doppler effect for acoustic waves, and the Moessbauer effect principle. The temperature effect on the Moessbauer effect is explored, along with the absorption detected during solid heating and the magnetization's role in determining lines and distances.