Thus one cannot (in the context of quantum theory) meaningfully assign an exact position and (simultaneously) an exact momentum (= velocity x mass) to a subatomic particle, for instance an electron. This feature (exact position and momentum) is thus not (objectively) observable. But this is just because of the inadequateness of the particle model (a model that attributes particle character to entities like electrons). The behaviors of such subatomic entities sometimes yield to the particle-model (i.e. are explainable with the particle model), sometimes to the wave-model. In both cases they are just models, and it is the models that cause the above mentioned and other difficulties. So it is not correct to assert that the quantum theory would force us to accept particles which do not possess at every moment in time a well determined momentum and position.
back to main text