Wolfgang Pauli, the Story Of a Quantum Pioneer
Scientific contributions of one of the leading quantum physicists
Wolfgang Pauli was born in Vienna, on April 25th, 1900, the same year when Max Planck published his work on the theory of blackbody radiation pioneering modern quantum mechanics. During his early life, he had his education at the place he was born, and finally, at the later stages of his academic career, he had an opportunity to study under Arnold Sommerfeld (famous for his Bohr- Sommerfeld Atomic model) which might also be the reason that peaked his interest about his research on finding out the peculiar characteristics of an atom in the realm of Quantum mechanics. He was a natural-born leader and a charismatic character. Even in his early years, he had already published papers on the theory of relativity. But the most important discovery of Pauli was the idea that laid the foundation for studies under Quantum mechanics. In general, it is very hard to distinguish the difference in particles in the field of quantum mechanics. Pauli basically gave the concept on how we could actually distinguish the peculiar difference between the quantum particles based on his theories and experiments.
The most famous work of Wolfgang Pauli would undeniably be Pauli’s exclusion principle. This principle was a stepping stone in the field of Quantum mechanics and so vital for further understanding of the characteristics of an atomic model that its name was attached along with his name. This ultimately won him a Nobel prize in 1945 after being nominated by Albert Einstein himself. The basic idea of this principle was that ‘no two electrons could have all 4 sets of identical quantum numbers.’ What it basically means is that even if the two electrons had 3 identical values for the quantum numbers say n,l, and m, then where they would definitely have to differ would be in the value of the Spin quantum number. If one has a clockwise spin, then the other one must have an anti-clockwise spin. This was a pioneering step toward finding the difference in particles in the field of Quantum mechanics.
Another revolutionary contribution of Pauli was the postulation of Neutrinos. Neutrinos are basically particles that neither have any mass nor any charge. To be able to detect something of this nature scientifically, the objects must first interact with the natural environment. But neutrinos are contrary to that. Before the discovery of neutrinos, no one had any idea where the lost energy after the decay of an atomic nucleus had gone as it had to present itself in some form of energy as a result of the conservation of Energy. Pauli for the first time proposed that the same energy would be expressed in the form of neutral (chargeless) and lightweight (massless) particles called neutrinos. Note that Pauli was a theoretical physicist, thus when he first discovered this trait, he didn’t rush to conclusions but found it wise to consult with experimental physicists. Later in 1956, they were discovered by Frederick Reines and his team.
It was later discovered that the concept of quantum numbers could not only just be assigned and limited to electrons in an atom, but also could be assigned for Protons and Neutrons. Also, the concept of Pauli’s exclusion principle could be assigned to either of them. Neutrons and protons could be easily distinguishable in an atom as neutrons are chargeless particles and not affected by Columb forces whereas Protons are positively charged particles and their nuclear forces are certainly dependent on Columb forces. The application of Pauli’s exclusion principles even for these fundamental particles of an Atom broadened the horizon of further research in the field of Quantum Mechanics.
“The best that most of us can hope to achieve in physics is simply to misunderstand at a deeper level.”
— Wolfgang Pauli
He also came up with the idea of the spin-statistics theorem. This theorem basically relates the spin of the Quantum particles to the particle statistics they’re bound to follow. The subatomic particles could either have an integer value of spin or otherwise. Under this concept of relating the spin of subatomic particles to a more discrete statistical nature, for the subatomic particles with the integral values of spin, there have been found to correlate with Bose-Einstein statistics and for the subatomic particles with half-integral values of spin, could be correlated with Fermi-Dirac statistics.
Orbitals are the fundamental ground for residing electrons. To have the basic concept of the maximum amount of electrons that could reside in an orbital, the groundwork laid by Pauli is essential. Using Pauli’s principle, we could conclude the fact that at maximum, two electrons could reside in an orbital, with 3 identical quantum numbers, only differing in their spin i.e. if one has a clockwise spin with (+1/2) spin quantum number, then the other must have anticlockwise spin with (-1/2 ) spin quantum number.
Wolfgang Pauli has had some of the greatest contributions to the development of modern quantum theory along with particle and nuclear physics. This titan of quantum mechanics died in December 1958.
Contributed by Rishab Karki and curated by the author.
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