This book is composed of two parts. Both parts combine into a single theory, but for easier description of phenomena, they were presented as independent of each other. This book is an attempt to show the Theory of Relativity in “different” light. That is, so to speak, physics without relativism. Each experiment described in the book comprises visual, mathematical and numerical analyses. All possible cases of setting the light source on-board a very fast vehicle were analysed. The conclusions are indeed surprising. Part_2 It is a modified version of a well-known experiment with light clock. The experiment has been improved in relation to the original. Optical clock was replaced with a laser. Laser beam may depart laser’s interior thus becoming observable (not just in theory). Experiment – L has been designed as a “broad” angular analysis. Various laser positions on-board the vehicle were thoroughly examined. One can literally say that laser’s beam is analysed in terms of every angle. As a result of the analyses performed, the “true” nature of time has been discovered. A mathematical proof that time has absolute nature has been presented.