Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

DC Josephson effect occurs because of this effect. This effect is used in STMs, which are a type of microscopes. Calculating the probability of this happening for a Heaviside step function requires using the boundary conditions that the wavefunction and its derivative have to be continuous everywhere. The probability of this happening has a hyperbolic sine squared in its denominator and this was used to explain (*) alpha decay as protons would need a large amount of energy to leave the nucleus. This effect happens when a potential barrier is greater than the energy of a moving particle and the particle moves through the barrier. For 10 points, name this quantum mechanical effect.
Science