Regarding a quantum leap, a particle goes from one place to another instantaneously - it is said - say an electron switching between levels. If a particle were to switch from one place to another, how would you know it was one particle moveing in space, and not two particles alternately appearing and disappearing ? I have never seen anything to say that one electron is distinguishable from another - they are not like dogs whereby you can say that it is definitely your dog moving from one place to another because you recgnise his coat. Surely the existence of distinguishing features is one of the fundamentals of recognising an object, and if uniquely distinguishing features are missing then you cannot say that you recognise an object, and therefore cannot identify it, and single it out from all the others, to say that it moved ? Isn't that fundamental unique identifier lacking in the subatomic world ?