The Pauli exclusion principle is the quantum mechanical principle that no two identical fermions (particles with half-integer spin) may occupy the same quantum state simultaneously. A more rigorous statement is that the total wave function for two identical fermions is anti-symmetric with respect to exchange of the particles. The principle was formulated by Austrian physicist Wolfgang Pauli in 1925.
For example, no two electrons in a single atom can have the same four quantum numbers; if n, l, and ml are the same, ms must be different such that the electrons have opposite spins, and so on.
Integer spin particles, bosons, are not subject to the Pauli exclusion principle: any number of identical bosons can occupy the same quantum state, as with, for instance, photons produced by a laser and Bose-Einstein condensate.
In this fascinating short excerpt from BBC’s A Night With The Stars, physicit Brian Cox turns to the Pauli exclusion principle to explain why everything is connected to everything else, an idea at once utterly mind-bending and utterly intuitive, found everywhere from the most ancient Buddhist scripts to the most cutting-edge research in biology and social science.
“The universe is made of stories, not atoms,” poet Muriel Rukeyser famously remarked. “We’re made of star-stuff,” Carl Sagan countered. But some of the most fascinating and important stories are those that explain atoms and “star stuff.” Such is the case of "The Quantum Universe: Everything That Can Happen Does Happen" by physicist Brian Cox and University of Manchester professor Jeff Forshaw — a remarkable and absorbing journey into the fundamental fabric of nature, exploring how quantum theory provides a framework for explaining everything from silicon chips to stars to human behavior.
More on this discussion can be found here.
For example, no two electrons in a single atom can have the same four quantum numbers; if n, l, and ml are the same, ms must be different such that the electrons have opposite spins, and so on.
Integer spin particles, bosons, are not subject to the Pauli exclusion principle: any number of identical bosons can occupy the same quantum state, as with, for instance, photons produced by a laser and Bose-Einstein condensate.
In this fascinating short excerpt from BBC’s A Night With The Stars, physicit Brian Cox turns to the Pauli exclusion principle to explain why everything is connected to everything else, an idea at once utterly mind-bending and utterly intuitive, found everywhere from the most ancient Buddhist scripts to the most cutting-edge research in biology and social science.
“The universe is made of stories, not atoms,” poet Muriel Rukeyser famously remarked. “We’re made of star-stuff,” Carl Sagan countered. But some of the most fascinating and important stories are those that explain atoms and “star stuff.” Such is the case of "The Quantum Universe: Everything That Can Happen Does Happen" by physicist Brian Cox and University of Manchester professor Jeff Forshaw — a remarkable and absorbing journey into the fundamental fabric of nature, exploring how quantum theory provides a framework for explaining everything from silicon chips to stars to human behavior.
More on this discussion can be found here.
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