This lecture explores Young's famous experiment with two slits, demonstrating the dual nature of quantum objects as both waves and particles. Starting with waves on water, the instructor explains interference patterns and continuous phenomena. Moving to particles, the lecture discusses discrete behaviors and the observation of density profiles. The experiment with single electrons and Bose-Einstein condensates is also covered, highlighting interference fringes and collective atomic behavior. The presentation concludes by addressing the limitations of classical concepts in describing quantum objects, emphasizing the need for a new understanding beyond wave-particle duality.