Quantum physics, also known as quantum mechanics, is a fundamental branch of physics that deals with the behavior of matter and energy at the smallest scales. It provides a mathematical framework to describe the behavior of particles, such as electrons, photons, and atoms, in a microscopic world where classical physics laws no longer apply.
At its core, quantum physics introduces the concept of quantization, which states that certain physical properties, such as energy, momentum, and angular momentum, can only take on specific discrete values. This stands in contrast to classical physics, where these properties are continuous and can take on any value.
Quantum physics is built upon a few key principles:
Superposition: According to the principle of superposition, a quantum system can exist in multiple states simultaneously. This means that a particle can be in a state of being both here and there, or in a combination of different energy levels. Only when a measurement is made does the system "choose" one of these possibilities, collapsing into a definite state.
Wave-particle duality: Quantum physics describes particles as both particles and waves. This duality implies that particles, such as electrons or photons, can exhibit wave-like behavior, such as interference and diffraction. The wave-particle duality is encapsulated in the concept of the wavefunction, which mathematically describes the probability distribution of a particle's properties.
Uncertainty principle: The uncertainty principle, formulated by Werner Heisenberg, states that certain pairs of physical properties, such as position and momentum, cannot be simultaneously measured with arbitrary precision. The more precisely one property is known, the less precisely the other can be determined. This fundamental principle places limitations on the precision of measurements in the quantum realm.
Quantum entanglement: Quantum entanglement is a phenomenon where two or more particles become correlated in such a way that the state of one particle is instantaneously related to the state of the other, regardless of the distance between them. This non-local correlation has been experimentally observed and is a key feature of quantum mechanics.
Quantum physics has numerous applications in various fields, including atomic and molecular physics, solid-state physics, quantum computing, quantum cryptography, and quantum optics. It has revolutionized our understanding of the microscopic world and is essential for explaining phenomena that cannot be described by classical physics, such as the behavior of particles inside an atom or the properties of quantum systems.