In order to know the actual location of the electron, a measurement must be made, and here is where the troubles begin for the die-hard determinists.… - Michael S. Gazzaniga

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In order to know the actual location of the electron, a measurement must be made, and here is where the troubles begin for the die-hard determinists. Once a measurement is made, the quantum state is said to collapse, meaning that all the other possible states the electron could have been in (known as superpositions) have collapsed into one. All the other possibilities have been eliminated. The measurement, of course, was irreversible and had constrained the system by causing the collapse. Over the next couple of years physicists realized that neither the classical concept of “particle” nor that of “wave” could fully describe the behavior of quantum-scale objects at any one point in time. As Feynman quipped, “They don’t behave like a wave or like a particle, they behave quantum mechanically.”18