Explore the groundbreaking concepts behind the 2022 Nobel Prize in Physics in this 56-minute colloquium presented by Dr. hab. Rafał Demkowicz-Dobrzański from the Faculty of Physics at Warsaw University. Delve into the fascinating world of quantum mechanics, starting with the EPR argument and progressing through hidden variables, the Copenhagen interpretation, and Bell inequalities. Examine pivotal experiments by Clauser and Aspect, and discover the significant advancements in experimental quantum optics achieved in 2015. Learn about the practical applications of quantum mechanics in secure key distribution and device-independent Quantum Key Distribution. Gain insights into Zeilinger's achievements and understand how mainstream physicists interpret quantum mechanics. Conclude by exploring the philosophical implications of quantum theory, questioning the nature of wave functions and challenging classical intuitions about the fundamental nature of reality.