Quantum tunnelling is a strange effect in quantum physics where very tiny things, like electrons, can pass through walls or barriers that they shouldn't be able to cross if the usual rules of physics applied. Imagine throwing a ball at a wall—normally, the ball would just bounce back, but in the quantum world, the ball could sometimes magically appear on the other side without climbing over the wal. This happens because particles act like waves that can stretch through barriers, and there is a small chance that the particle will end up on the other side, even though it doesn’t have enough energy to go over.
