Conserved charge
= Conserved charge
{title2=$Q=\int j^0\,dx$}
An integral of the time component of a <conserved current> is a <conserved charge> when the spatial boundary flux vanishes. Charges need not come from an immediately apparent elementary symmetry; a field theory can have an infinite higher-derivative current hierarchy. A <Noether charge> is obtained from the symmetry current supplied by the <Noether theorem>.