Hi All, A one dimensional soliton will have the mathematical form [itex] f(x - ct) [/itex] where c is the speed of propagation and f represents some envelope function. If we suppose that c1 is a speed and c2 another one where c2>c1. If E1 is the energy needed to maintain the speed and shape of the soliton. What happens when the speed change from c1 to c2? 1/ if the shape is constant? 2/ if the shape is reduced? 3/ Is the energy needed enlarged/augmented?