Panmere

There is a difference between quantum mechanics (the theory) and the reality it is describing (electrons etc.). Electrons are not wave packets flying around in space. Electrons are physical objects, wave packets are theoretical notions. Probably the only way to have a wave packet flying in space is by throwing one’s quantum mechanics textbook. If a quantum mechanical observable were a Hermitian operator, one could observe it by looking into one’s quantum mechanics textbook. These trivial remarks are not superfluous because whole generations of physicists have been trained to think about electrons as wave packets flying around in space, and to see values of Hermitian operators as properties of microscopic objects.
— Willem de Muynck , www.phys.tue.nl/ktn/Wim/muynck.htm