Physics for CSS

On 24 April in 1914, the Franck-Hertz experiment was first presented in a paper in the German Physical Society by James Franck and Gustav Hertz.

Their experimental results supported a theory previously put forward by Niels Bohr – which stated that atoms were made up of a nucleus orbited by electrons at fixed energies.

In the experiment Franck and Hertz applied a potential difference to a tube containing a low-pressure gas. When increased, the current flowing through the tube also increased until the voltage reached a certain level, when it suddenly declined.

Even though they hadn't heard of Bohr's atomic model – based on early quantum theory – when they performed their experiment, Franck and Hertz later realised their paper supported it. The potential difference in their experiment increased the free electrons' mobility until the electrons had enough energy to jump up to the next energy level, just like Bohr predicted.

Photos left to right: James Franck, a vacuum tube used in the experiment (E. A. Schiff Wikimedia commons) and Gustav Hertz.

Wolfgang Pauli (1900-1958) was an Austrian theoretical physicist who made significant contributions to the development of quantum mechanics and the understanding of the behavior of subatomic particles.
Pauli is best known for the "Pauli exclusion principle," which states that no two electrons in an atom can occupy the same quantum state simultaneously. This principle is a fundamental concept in quantum mechanics and has important implications for understanding the behavior of atoms and molecules.
Pauli also made important contributions to the development of the theory of relativity, the study of cosmic rays, and the field of particle physics. He was awarded the Nobel Prize in Physics in 1945 for his work on the exclusion principle.
Pauli was also known for his sharp wit and his sometimes abrasive personality. He was famously critical of theories that he considered flawed or incomplete, earning him the nickname "the conscience of physics."

The Pauli exclusion principle is a fundamental principle in quantum mechanics that can be described mathematically using the concept of wave functions. The wave function of a particle is a mathematical function that describes the probability distribution of finding the particle in different locations and states.

For identical fermions, the wave function must be antisymmetric under the exchange of their positions. This can be expressed mathematically as:

Ψ(x1,x2) = -Ψ(x2,x1)

where Ψ is the wave function, x1 and x2 are the positions of the two identical fermions, and the minus sign indicates the antisymmetry requirement.

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CSS Physics: Vectors-1 Vectors, scalar product, vector product, triple product

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Vectors, dot and cross product, triple product

CSS Physics: Vectors-1 Vectors, scalar product, vector product, triple product

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https://physicstoday.scitation.org/doi/10.1063/PT.3.5133?ptfb&fbclid=IwAR2uqCj1f5LGabUdXyOCKPwjrVxsR0CnK4seS5bquAO4YUv2l0he9YpXN0g

Physics Nobel honors foundational quantum entanglement experiments The laureates brought the conceptual features of quantum physics back to mainstream interest.