: "Defining the Quantum-Classical Boundary: A New Transition Constant Using Critical Velocity and Planck's Constant"

This thesis introduces a novel approach to understanding the quantum-to-classical transition through the concept of critical velocity. By integrating the Planck constant, particle mass, and a proposed critical velocity, a new quantum-classical transition constant is defined, offering a quantifiable boundary where quantum behavior gives way to classical mechanics. This study formulates the constant Cqc=hmvcC_{qc} = \frac{h}{m v_c}Cqc=mvch and explores its implications across various domains, from fundamental physics to practical applications like quantum computing and cosmology. This constant aims to unify existing theories of quantum decoherence and classical dynamics, providing a deeper insight into the nature of reality.