1. The problem statement, all variables and given/known data Hi all. Please take a look at: http://en.wikipedia.org/wiki/Particle_in_a_box My problem is: I do not know how to interpret the eigenfunction of a particle in an infinite square well. We have that the wave function is a function of sine, and Psi_1 has no nodes, Psi_2 has one node, Psi_3 has two nodes and so on, i.e. they look like standing waves on a string. What are these nodes an expression for? What do they mean? And does the wave function mean that the particle in the infinite square well oscillates around the energy-levels?