In relativistic quantum mechanics, the Klein paradox was an unexpected effect of relativity on the predictions of quantum tunneling theory for particles encountering high potential-energy barriers. The phenomenon itself is now known as Klein tunneling. It is named after physicist Oskar Klein who discovered it in 1929. Originally, Klein obtained a paradoxical result by applying the Dirac equation to the familiar problem of electron scattering from a potential barrier. In nonrelativistic quantum mechanics, electron tunneling into a barrier is observed, with exponential damping. However, Klein's result showed that if the potential is at least of the order of the electron mass , the barrier is nearly transparent. Moreover, as the potential approaches infinity, the reflection diminishes and the electron is always transmitted.