Notice that the only explanation for quantum tunneling is if the position of the electron is truly spread
out, not just hidden or unmeasured. Its raw uncertainty allows for the wave
function to penetrate the barrier. This is genuine indeterminism, not simply
an unknown quantity until someone measures it.
It is important to note that the superposition of possibilities
only occurs before the entity is observed. Once an observation is made (a position
is measured, a mass is determined, a velocity is detected) then the superposition
converts to an actual. Or, in quantum language, we say the wave function has
collapsed.
The collapse of the wave function by observation is a
transition from the many to the one, from possibility to actuality. The identity
and existence of a quantum entities are bound up with its overall environment
(this is called contextualism). Like homonyms, words
that depend on the context in which they are used, quantum reality shifts its
nature according to its surroundings.