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DYK-01 Pauli's Reaction to Discovery of Matrix Mechanics

Node id: 1822page
kapoor's picture 21-08-26 12:08:04 n

DYK-09 Who gave the name "Quantum Mechanics"?

Node id: 2961page
kapoor's picture 21-05-21 01:05:12 n

DYK-13 Sommerfeld's theory of atoms

Node id: 3107page
kapoor's picture 21-05-20 04:05:28 n

DYK-12 :: What is a gauge? as Explained by Pankaj Sharan

Node id: 3103page


The following (from notes for a lecture I was preparing) might help explain the context: The first gauge theory was Hermann Weyl's extension of Einstein's general theory of relativity with a parallel transport that can change the scale or 'gauge' of lengths of the transported vector. About this one can read in P. G. Bergman's book on Relativity. The Hamiltonian formulation of electrodynamics, and in particular, the replacement of \(\vec{p}\) by \(\vec{p}-e\vec{A}/c \) was given by Larmor in his book "Aether and Matter", Cambridge (1900). [quoted by Pauli in ''General Principles of Quantum Mechanics" , Section 4. (Tr. by P. Achuthan and K. Venkatesan of 1958 German edition) Allied, New Delhi 1980.] In quantum mechanics the 'canonical momentum' \(\vec{p}-e\vec{A}/c\) becomes \(-i\hbar[\nabla-ie\vec{A}/(\hbar c)]\). The gauge invariance of the Schrodinger theory under \(\vec{A}\to \vec{A}+\nabla f\) and \(\phi\to \phi-(e/c)\frac{\partial f}{\partial t} \) when \(\Psi\) is changed by a phase was first given by V. Fock (1927). The analogy of this group of transformations to the Weyl theory on gravitation and electricity was pointed out by F. London (1927). The connection of this group to charge conservation was pointed out by Weyl while writing variational principle for the wave equation. [See Pauli as above.]

kapoor's picture 20-02-08 16:02:30 n

DYK-10 Schrodinger was never comfortable with quantum jumps

Node id: 2962page
kapoor's picture 20-02-08 16:02:30 n

DYK-08 Who proposed electron spin first and what happened to the proposal?

Node id: 2114page
kapoor's picture 20-02-08 16:02:30 n

DYK-07 How good is Newtonian mechanics for planetary motion?

Node id: 1899page
kapoor's picture 20-02-08 16:02:30 n

DYK-06 Position Operator in Relativistic Quantum Mechanics

Node id: 1831page
kapoor's picture 20-02-08 16:02:30 n

DYK-05 Change in Sign of Fermion Wave Function under 2$\pi$ Rotation

Node id: 1830page

It is well known the wave function of a fermion changes sign under rotation by \(2\pi\). Has this been verified experimentally?

kapoor's picture 20-02-08 16:02:30 n

DYK-04 Who Revived the Klein Gordon Equation?

Node id: 1828page

The Klein Gordon equation in its original  interpretation suffered from problem of negative probabilities. After quantum electrodynamics was successfully formulated, the second quantized Klein Gordon equation was shown to give a consistent formulation for spin zero particles. WHO DID THIS WORK?

kapoor's picture 20-02-08 16:02:30 n

DYK-03 Jacobi Action Principle

Node id: 1827page

Jacobi Action Principle
A Second Variational Principle for Conservative Systems

Hamilton.'s action principle in classical mechanics is widely taught. There is a lesser known, but important Jacobi principle which is like Fermat's principle for waves. This form of action principle  was used by Schrodinger to arrive at his hafous equation for qunatum mechanics of a point particles. 

 

 

kapoor's picture 20-02-08 16:02:30 n

DYK-02 Connection beteen Keplers and Hooke's force laws

Node id: 1826page

Coulomb's force law and Hooke's law are connected by a transformation called Bohlin's transformation.

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kapoor's picture 20-02-08 16:02:30 n
 
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