Quantum mechanics arose as a fundamental theory to describe the behavior of particles at the atomic and subatomic levels. It was developed to address several problems and inconsistencies encountered in classical mechanics. Here are some of the key issues that quantum mechanics seeks to address:
Wave-particle duality: Classical mechanics treats particles as distinct particles with well-defined positions and velocities. However, experiments like the double-slit experiment revealed that particles can exhibit wave-like properties, such as interference and diffraction. Quantum mechanics introduced the concept of wave-particle duality, which describes particles as both particles and waves simultaneously.
Uncertainty principle: Classical mechanics allows for precise measurements of both position and momentum of particles. However, quantum mechanics introduced the Heisenberg uncertainty principle, which states that there is a fundamental limit to the simultaneous precision of measuring certain pairs of physical properties, such as position and momentum or energy and time. This uncertainty arises due to the wave-like nature of particles.
Quantization of energy: Classical mechanics allows for continuous values of energy. In contrast, quantum mechanics introduced the concept of quantization, where certain physical quantities, such as energy, are restricted to discrete values. This was exemplified by the quantization of energy levels in atoms, as observed in atomic spectra.
Non-locality and entanglement: Classical mechanics assumes that physical systems have local properties, meaning that the properties of one particle are independent of the properties of other particles unless they interact. However, quantum mechanics introduced the phenomena of entanglement, where particles can become correlated in such a way that the state of one particle cannot be described independently of the state of another, even when they are physically separated.
Measurement problem: Quantum mechanics introduced a probabilistic interpretation of measurement outcomes, where the act of measurement can alter the state of a system. This led to debates and philosophical questions about the nature of reality and the role of the observer in quantum mechanics. The measurement problem seeks to address how and why measurement collapses the wavefunction into a definite state.
These are just a few examples of the problems with classical mechanics that quantum mechanics seeks to address. Quantum mechanics provides a more accurate and comprehensive framework for describing the behavior of particles at the microscopic level, but it does not invalidate classical mechanics, which remains valid for macroscopic objects in everyday life.