= Scalar-field momentum flux
{title2=$T^{01}=-\phi_t\phi_x,\quad T^{11}=\tfrac12\phi_t^2+\tfrac12\phi_x^2-V$}
For a real <scalar field> in one spatial dimension with metric signature $(+,-)$ and potential $V$, the <stress-energy conservation> law is $\partial_tT^{01}+\partial_xT^{11}=0$. The force on the field to the left of a fixed cut is $-T^{11}$ at the cut when the far-left boundary flux vanishes. <Finite-energy field configurations> also permit this conclusion by spatial cutoffs, without assuming pointwise decay of all derivatives.
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