Yinuo Guo 2026. CLASSICAL VS. QUANTUM BEHAVIOR IN THE PARTICLE-IN-A-BOX MODEL: Received: 16th January 2026, Revised: 23rd March 2026, Accepted: 17th June 2026, Date of Publication: 14th August 2026. MATTER: International Journal of Science and Technology. 12, (Aug. 2026), 37–54. DOI:https://doi.org/10.20319/mijst.2026.12.3754.