Fundamental theory in physics describing the properties of nature on an atomic scale.
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties 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.
Quantum mechanics has been pivotal in understanding the physical world at the minutest scale. It has not only explained the behavior of particles at the atomic and subatomic level but also paved the way for the development of many technological advancements such as lasers, semiconductors, and magnetic resonance imaging (MRI).
The principles of quantum mechanics are also crucial for the study of chemistry and materials science, as they provide a framework for understanding the behavior of molecules and compounds. Furthermore, the field of quantum computing, which has the potential to revolutionize information processing, is entirely based on quantum mechanical principles.
Classical physics, which includes theories such as Newton's laws of motion and Maxwell's equations for electromagnetism, works well for describing the behavior of macroscopic objects but fails at very small (atomic and subatomic) scales or very high energies. This is where quantum mechanics comes into play.
Unlike classical physics, which states that these systems can have any amount of energy, quantum mechanics shows that they can only exist in certain discrete energy states. Moreover, while classical physics assumes that particles have definite properties, quantum mechanics allows particles to exist in multiple states at once, a phenomenon known as superposition.
Quantum mechanics is built on several core principles:
Quantum States: In quantum mechanics, the state of a physical system is described by a wave function, which provides the probabilities of the outcomes of different measurements of the system.
Superposition: This principle states that any two (or more) quantum states can be added together, or "superposed", and the result will be another valid quantum state.
Entanglement: Quantum entanglement is a phenomenon where two particles become interconnected and the state of one particle is immediately connected to the state of the other, no matter the distance between them.
Uncertainty Principle: Formulated by Werner Heisenberg, the uncertainty principle states that the position and momentum of a particle cannot both be precisely measured at the same time.
Wave-Particle Duality: This principle, central to quantum theory, posits that all particles exhibit both wave and particle properties.
Measurement: In quantum mechanics, the act of measurement changes the system. This is often referred to as "collapsing the wave function".
These principles, while challenging and counterintuitive, form the backbone of quantum mechanics and have been confirmed by a vast amount of experimental evidence. Understanding them is crucial to delve deeper into the fascinating world of quantum physics.