Newtonian physics, also known as classical physics, provides an accurate description of the physical world at macroscopic scales, such as those encountered in everyday life. However, it has limitations when it comes to describing phenomena at extremely small scales or high energies. Here are some key limitations of Newtonian physics:
Wave-particle duality: In the early 20th century, experiments revealed that particles such as electrons and photons exhibit both wave-like and particle-like properties. Newtonian physics treats particles as distinct, localized entities, whereas quantum physics recognizes that particles can behave as waves and exhibit wave-particle duality. This duality is a fundamental aspect of quantum mechanics.
Uncertainty principle: According to the Heisenberg uncertainty principle, it is impossible to simultaneously know the precise position and momentum of a particle with arbitrary accuracy. This principle places inherent limits on the precision of simultaneous measurements of certain pairs of physical properties. In Newtonian physics, there is no such uncertainty, and precise measurements of both position and momentum would be theoretically possible.
Quantization of energy: Quantum physics introduced the concept of quantization, where energy, as well as other physical quantities, can only exist in discrete, quantized levels. In contrast, classical physics assumes a continuous range of possible values for energy. The quantization of energy is crucial in understanding atomic and subatomic systems, such as electron energy levels in atoms.
Superposition and entanglement: Quantum mechanics allows for the existence of superposition states, where particles can exist in multiple states simultaneously. Additionally, entanglement refers to the phenomenon where two or more particles become correlated in such a way that the state of one particle is instantly related to the state of another, regardless of the distance between them. These phenomena have no direct analogues in classical physics.
Tunneling and particle behavior: Quantum mechanics describes the phenomenon of quantum tunneling, where particles can pass through energy barriers that would be classically forbidden. It also explains the behavior of particles at the quantum level, such as wave interference, which cannot be explained by classical physics.
We need quantum physics to accurately describe and understand the behavior of particles and systems at the quantum level. Quantum mechanics provides a more comprehensive framework for explaining the behavior of subatomic particles, atoms, molecules, and other quantum systems. It is essential for understanding phenomena in fields like atomic and molecular physics, condensed matter physics, quantum chemistry, and quantum information science.
Moreover, quantum physics is the basis for technologies such as quantum computing, quantum cryptography, and quantum sensing, which have the potential to revolutionize computation, communication, and measurement. Without quantum physics, we would lack the theoretical foundation and tools necessary to explain and exploit the unique characteristics of the quantum world.