(1/2)*(d/dR)*(hν/C)^2=(d/dR){ (GM/R) - (hν)^2/(2C^2) }
hν=hν/√(1-2GM/(RC^2))
(1/2)*(d/dR)*(hν/C)^2= -GM/R^2+(hν)^2*GM/(RC^2-2GM)^2
(hν)^2*GM/(RC^2-2GM)^2 だけ重力が減少する