"Particle in a box" question The solution of Schrodingers equation for the simple "particle in a box" problem is: E = (n^2)(h^2) / 8m(L^2) where L = the length of the box. See http://en.wikipedia.org/wiki/particle_in_a_box Say that the initial energy of the particle is E1. If at a later time the length of the box is changed (a moveable wall), then there are now a completely new set of possible energies available, for n=1,2,3 etc. What if none of these new allowed energies equals the original energy of the particle? What happens to the energy difference?