Definition:Gauge Transformation
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Definition
A gauge transformation is a mathematical reformulation of a physical theory that does not change the physical interpretation.
Examples
Magnetic Field
Consider the magnetic fields $\mathbf E$ and $\mathbf B$.
They can be written in terms of scalar potential $\phi$ and vector potential $\mathbf A$ as:
\(\ds \mathbf E\) | \(=\) | \(\ds -\nabla \phi - \dfrac {\partial \mathbf A} {\partial t}\) | ||||||||||||
\(\ds \mathbf B\) | \(=\) | \(\ds \nabla \times \mathbf A\) |
These may be changed by means of the gauge transformation:
\(\ds \phi\) | \(\to\) | \(\ds \phi + \dfrac {\partial \phi} {\partial t}\) | ||||||||||||
\(\ds \mathbf A\) | \(\to\) | \(\ds \mathbf A - \nabla \phi\) |
The physical quantities $\mathbf E$ and $\mathbf B$ have not been changed, but the purely mathematical $\phi$ and $\mathbf A$ have.
Also see
- Results about gauge transformations can be found here.
Sources
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): gauge transformation