This is because, according to the laws of quantum mechanics, it is possible to have transitions between two states, even in the presence of an energy barrier separating the two states, and the phenomenon is called, quite appropriately, quantum tunneling.
To je zbog toga što su, prema zakonima kvantne mehanike, mogući prijelazi između dva stanja, čak i ako postoji energetska barijera koja razdvaja dva stanja, a ta se pojava naziva, sasvim prikladno, kvantnim tuneliranjem.