# Quantum Mechanics

Quantum mechanics is a fundamental theory in physics that describes the behavior of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics, including quantum chemistry, quantum field theory, quantum technology, and quantum information science.

Classical physics, which existed before the advent of quantum mechanics, describes many aspects of nature at an ordinary (macroscopic) scale but is not sufficient for describing them at small (atomic and subatomic) scales. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large (macroscopic) scale.

Quantum mechanics introduces the concept of superposition, which allows particles or systems to exist in multiple states or configurations simultaneously until measured or observed. This means that until a measurement is made, a particle can be in a combination or “superposition” of different states. The superposition is described mathematically using wave functions.

When a measurement is made on a quantum system, the superposition collapses into a single state. This is known as the collapse of the wave function. The act of measurement disturbs the system and forces it to choose one of the possible states, with the probability of observing each state determined by the coefficients in the superposition.

Quantum mechanics has profound implications for our understanding of the microscopic world. It forms the basis for phenomena such as interference and entanglement, and it has applications in various fields, including quantum computing, quantum cryptography, and quantum sensing.

Quantum mechanics is a fascinating and complex theory that has revolutionized our understanding of the fundamental nature of reality at the smallest scales.

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