  A one-hundred-year old controversy, the Abraham-Minkowski controversy,
concerns two widely disparate predictions for the momentum of light in glass.
In the Abraham case the photon momentum is inversely proportional to the index
of refraction while the photon momentum predicted by Minkowski formulation is
proportional to the index of refraction. In spite of significant theoretical
and experimental effort neither formulation could convincingly be shown to be
correct. A new model, called the Mass Polariton model, MP, was recently
introduced that resolves the contradictions in the Abraham and Minkowski
formulations and experimental results. Both the MP and Minkowski model predict
the same momentum change for a photon entering glass from a vacuum, yet the
Minkowski model allows violation of the center of mass theorem. This paper
shows that the MP model, in spite of predicting the same momentum change as the
Minkowski model, obeys the center of mass theorem.
