Posts

Showing posts from February 27, 2019

Arvid Horn

Image
.mw-parser-output .infobox{border:1px solid #aaa;background-color:#f9f9f9;color:black;margin:.5em 0 .5em 1em;padding:.2em;float:right;clear:right;width:22em;text-align:left;font-size:88%;line-height:1.6em}.mw-parser-output .infobox td,.mw-parser-output .infobox th{vertical-align:top;padding:0 .2em}.mw-parser-output .infobox caption{font-size:larger}.mw-parser-output .infobox.bordered{border-collapse:collapse}.mw-parser-output .infobox.bordered td,.mw-parser-output .infobox.bordered th{border:1px solid #aaa}.mw-parser-output .infobox.bordered .borderless td,.mw-parser-output .infobox.bordered .borderless th{border:0}.mw-parser-output .infobox-showbutton .mw-collapsible-text{color:inherit}.mw-parser-output .infobox.bordered .mergedtoprow td,.mw-parser-output .infobox.bordered .mergedtoprow th{border:0;border-top:1px solid #aaa;border-right:1px solid #aaa}.mw-parser-output .infobox.bordered .mergedrow td,.mw-parser-output .infobox.bordered .mergedrow th{border:0;border-right:1px solid

Are Maxwell's equations “physical”?

Image
9 5 The canonical Maxwell's equations are derivable from the Lagrangian $${cal L} = -frac{1}{4}F_{munu}F^{munu} $$ by solving the Euler-Lagrange equations. However : The Lagrangian above is invariant under the gauge transformation $$A_mu to A_mu - partial_mu Lambda(x) $$ for some scalar fiend $Lambda(x)$ that vanishes at infinity. This implies that there will be redundant degrees of freedom in our equations not motion (i.e. Maxwell's equations). Therefore, as I understand gauge fixing, this implies that Maxwell's equations (without gauge fixing) can lead to unphysical predictions. Question : Hence my question is simply are Maxwell's equations (the ones derived from $cal{L}$ above) actually physical, in the sense they do not make unphysical predictions? Example: The general solution to