quantum mechanics

Quote by Niels Bohr

"If somebody says that he can think about quantum physics without becoming dizzy, that shows only that he has not understood anything whatever about it."

The science and mathematics that describes the behavior of nature at the atomic and subatomic level. At the heart of quantum mechanics are two basic concepts: 1) that every small bit of matter or energy can behave as if were either a particle or a wave (see wave-particle duality); and 2) that certain combinations of properties such as position and velocity, and energy and time, can't be known with arbitrary precision. The latter idea is encapsulated in Heisenberg's uncertainty principle.

Quantum mechanics was developed during the 20th century when it became clear that the existing laws of classical mechanics and electromagnetic theory were not successfully applicable to such systems. Because quantum mechanics treats physical events that we cannot directly perceive, it has many concepts unknown in everyday experience. Louis de Broglie struck out from the old quantum theory (see Max Planck and the origins of quantum theory) when he suggested that particles have a wavelike nature (see de Broglie and matter waves). This wavelike nature is significant only for very small particles such as electrons. These ideas were developed by Erwin Schrödinger and others into the branch of quantum mechanics called wave mechanics. Werner Heisenberg worked along parallel lines with a theory incorporating only observable quantities such as energy, using matrix algebra techniques and called matrix mechanics. Paul Dirac incorporated relativistic ideas into quantum mechanics.

Related categories

• ATOMIC AND NUCLEAR PHYSICS
• PARTICLE PHYSICS

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