But Maxwell third and fourth equations suggest that we can just have the forces cancel outside the two face of the portals by letting one portal be passive. The portal that we are traveling from is the active portal.
The active portal induces a corresponding force pair (\(\oint{E_{\psi}}\,d\,\lambda\)) in the passive portal that in turn generate a force that cancels with the force from the active portal, beyond the passive portal as expected.
Furthermore,
this is also a possible portal configuration. Two of such double pillars facing each other, with high \(g_T\) between one of the double pillars can generate a conduit between the portals.
