Quantum mechanics

Quantum mechanics is the over-arching contemporary theory in physics that provides a description of the properties of nature at the scale of atoms and subatomic particles.

  • Quantum mechanics is the foundation of all quantum physics including the sub-fields of particle physics, quantum field theory, quantum chemistry, quantum technology, and quantum information science.
  • Quantum mechanics is not an improvement on the world of classical mechanics. It is a completely new idea that grew out of discoveries about the structure of the atom and the world of sub-atomic particles that were unknown to the classical view of physics.
  • Modern quantum mechanics was born in 1925 and its development can be traced through the work of Bohr, Dirac, Einstein, Feynman, Planck and Schroedinger.
  • Quantum mechanics differs from classical physics in many ways, including:
    • Quantization: in quantum mechanics, energy, momentum, angular momentum, and other quantities are often restricted to discrete values.
    • Wave-particle duality: objects have characteristics of both particles and waves.
    • The uncertainty principle: given a complete set of initial conditions, there are limits to how accurately the value of a physical quantity can be predicted prior to its measurement.
    • Quantum entanglement: objects can be linked together in such a way that they share the same fate, even when separated by a large distances.