I'm having a little trouble understanding the equivalence principle explanation of the twin paradox. I understand that the resolution to the paradox according to the equivalence principle is that the non-traveling twin has a higher gravitational potential energy in the pseudo-gravitational field created when treating the traveling twin's reference frame as an inertial one, but I'm not sure that I understand why this is so. Doesn't gravitational potential energy at a particular point depend on the strength of the gravitational field at that point? If the twins have different gravitational potential energies, does this mean that the gravitational field is a different strength for each of them? And if this is the case, where is the pseudo-gravitational field at its strongest? For a massive body, the gravitational field is the strongest at the centre of the body. But being a flat pseudo-gravitational field in the case of the twin paradox, there obviously is no centre.