Mixed electromagnetic energy-flux signs
= Mixed electromagnetic energy-flux signs
{title2=$T^0{}_i=-S_i\quad(c=1)$}
With $(+---)$ signature and $c=1$, $T^0{}_0=(E^2+B^2)/(2\mu_0)$ while $T^0{}_i=-(\mathbf E\times\mathbf B)_i/\mu_0$. Raising the second index gives $T^{0i}=S_i$, where $\mathbf S$ is the <Poynting vector>, and symmetry gives the physical energy-flux components $T^{i0}$. The negative mixed component is a metric-sign effect, not reversed <energy> transport. In SI coordinates $x^0=ct$, $T^{i0}=S_i/c$.