Quantum mechanics is a branch of physics which deals with physical phenomena at microscopic scales. It departs from classical mechanics mainly at the quantum realm of atomic and subatomic length scales. Quantum physics provides a mathematical description of much of the particle-like and wave-like behavior and interactions of energy and matter. The mathematical formulations of quantum mechanics are abstract, using wavefunction to provide information about the probability amplitude of position, momentum, and other physical properties of the particle. Wavefunction treats objects as quantum harmonic oscillators, the mathematics of which are similar to acoustic resonance. Quantum theory has its origins in the early 20th century, at around the same time as atomic theory and the corpuscular theory of light.