Hi, My friends! According to quantum mechanics books ,a particle has some probability hop through the potential even when the potential is large than kinetic energy. They all explain the phenomenon by solving Schrodinger equation. Indeed, the wavefunction doesn't equal 0 behind the potential. But I want to know how the particle go through the potential? What is the physics behind quantum tunneling? I can't accept the explaination in books! Everyone who says something about quantum tunneling would be highly appreciated. let us talk about it!! best wishes!! PS: I read something about STM. the book says that because of tunneling ,the electron of metal are not confined the inner of surface,that is to say ,electron density don't fall to zero at the surface,but attenuation exp(), I want to know why the electron leaves the metal ,and they have pass the potential barrier!!!