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.