Quantum Mechanics QM;
also known as quantum physics,
quantum theory, mechanical
wave model or mechanical matrix,
including quantum field theory,
a fundamental theory of physics
that describes the nature
of the lower energy levels of atoms
and subatomic particles. Classical
physics, the physics that precedes
quantum mechanics, describes nature
on the usual macroscopic scale. Most
theories of classical physics can be
drawn from quantum mechanics as a
valid, large-scale, macroscopic approach.

Quantum mechanics differs from classical
physics to energy, momentum, spin
and other quantities of a linked system
limited to the quantification of discrete
values; Objects have both characteristics
and waves, a binary wave-particle
and there are limits to the precision
with which the quantities of the uncertainty
principle can be measured. Quantum
mechanics gradually generated theories
that explain observations incompatible
with classical physics, such as Max Planck's
1900 solution to black body radiation,
and the correspondence between energy
and frequency in Albert Einstein's 1905 paper,
which explains the function
of the photoelectric effect. The first quantum
theories were profoundly redesigned in the mid-1920s
by Erwin Schrödinger, Werner Heisenberg, Max Born
and others. Modern theory is based on a series
of specially formulated mathematical formalisms.
In one of these, a mathematical function,
the wave function, provides information
about the probability of amplitude
of the position, the amount of movement
and other physical properties of a particle.
The main applications of quantum theory
include quantum chemistry, quantum optics,
quantum computing, superconducting
magnets, light-emitting diodes, lasers,
transistors and semiconductors,
such as microprocessors, medical
imaging and images using magnetic
resonance and electron microscopy.
The explanations of many biological
and natural phenomena have their roots
in the nature of the chemical bond,
especially the macromolecular DNA.