Quantum mechanics is considered one of the most successful physical theories because it has been incredibly accurate and successful in describing a wide range of phenomena observed in the microscopic world. While it is true that quantum mechanics relies on several inputs, many of which cannot be derived from first principles, its success lies in its predictive power and the agreement between its theoretical predictions and experimental results. Here are some key points to consider:
Experimental Confirmation: Quantum mechanics has been rigorously tested and verified through countless experiments conducted over several decades. Its predictions have been confirmed with remarkable precision in numerous areas, including atomic and molecular physics, solid-state physics, particle physics, and quantum optics. The accuracy of these experimental verifications is a testament to the success of quantum mechanics.
Mathematical Consistency: Quantum mechanics is a mathematically consistent and self-contained theory. Although it relies on certain postulates and mathematical formalism, these elements have been developed based on extensive theoretical and experimental investigations. The mathematical framework of quantum mechanics provides a coherent and robust description of the microscopic world, enabling accurate calculations and predictions.
Predictive Power: Quantum mechanics has demonstrated its remarkable predictive power in a wide range of phenomena. It can accurately describe and predict the behavior of particles, atoms, molecules, and materials. It provides insights into the structure of matter, the behavior of electromagnetic radiation, and the interactions between particles. Quantum mechanics has also led to the development of numerous technological applications, such as lasers, transistors, and modern information technologies.
Quantum Mechanical Principles: While certain inputs in quantum mechanics may be taken as postulates, they are based on empirical observations and experiments. These principles, such as wave-particle duality, superposition, and entanglement, have been extensively tested and found to be consistent with experimental evidence. They provide a comprehensive framework for understanding and explaining the behavior of microscopic systems.
Limitations of Classical Physics: Classical physics, which includes Newtonian mechanics and Maxwell's equations, fails to describe many phenomena at the microscopic level. Quantum mechanics, on the other hand, provides a more accurate and comprehensive description of the microscopic world. It resolves many of the limitations and paradoxes of classical physics, such as the ultraviolet catastrophe, the stability of atoms, and the photoelectric effect.
It is important to note that the inputs and postulates of quantum mechanics are not arbitrary, but rather emerge from a combination of experimental observations, theoretical considerations, and mathematical consistency. While the foundational aspects of quantum mechanics are still subjects of ongoing research and debate, its practical success and ability to explain and predict a wide range of phenomena have made it one of the most successful theories in the history of physics.