The cornerstone of modern physics, which describes the laws of matter and energy at atomic scale (see
atom). The development of quantum mechanics started at the turn of the 20th century and combined with Einstein's general and special theory of relativity, it revolutionized the field of physics. Quantum mechanics also explains the behavior of semiconductors which are used to make the myriad devices we use every day.
For a mind-boggling comment about the atom from one of the world's greatest scientists, see
Does it matter?.
Theory, Mechanics and Physics
Quantum theory was the conviction that this behavior was valid, whereas "quantum mechanics" and "quantum physics" refer to the mathematical laws that were later proven to be true. However, all terms are used interchangeably by non-scientists. Following are the principles of the quantum world we live in. See
quantum state,
quantum leap and
quantum computing.
1. Particles
At the subatomic level, energy is made up of small particles, or packets, also known as "quanta." In quantum physics, energy is not a continuous inseperable stream. However, in classical physics, energy "is" considered continuous.
2. Wave-Particle Duality
Electrons and photons exhibit both wave and particle properties. See
wave-particle duality,
electron and
photon.
3. Superposition
An electron or photon can be in multiple states at the same time. See
quantum superposition.
4. Entanglement
Two particles can maintain their relationship over distance. See
quantum entanglement.
5. Uncertainty Principle
The measuring of either the momentum of an electron or its position disturbs the other. Knowing a particle's position means not being able to accurately know its momentum and vice versa.
6. Probabilistic Measurement
When a quantum system is measured, only one of its possible states is derived. See
probabilistic.
The Contributions
Following are the important contributors to quantum theory and the principles they uncovered.
Year Researcher Contribution
1901 Planck Blackbody radiation
1905 Einstein Photoelectric effect
1913 Bohr Spectra theory
1922 Compton Photon scattering
1924 Pauli Exclusion principle
1925 de Broglie Matter waves
1926 Schroedinger Wave equation
1927 Heisenberg Uncertainty principle
1927 Davison & Wave properties of
Germer electrons
1927 Born Interpretation of the
wavefunction