Quantum Mechanics

A branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter:

Quantum Mechanics (also known as Quantum Physics or Quantum Theory)
Quantum mechanics (QM) departs from classical mechanics primarily at the atomic and subatomic scales. In advanced topics of QM, some of these behaviors are macroscopic and only emerge at very low or very high energies or temperatures. The name, coined by Max Planck, derives from the observation that some physical quantities can be changed only by discrete amounts, or quanta, as multiples of the Planck constant, rather than being capable of varying continuously or by any arbitrary amount (read more ...).