In A Null Measurement, Where Is The Uncertainty Principle? Nowhere To Be Found- The Uncertainty Principle Does Not Protect A Null Measurement: Knowledge Does

At least some null measurements (nms) do not involve the uncertainty principle (up). To determine which path in an interferometer (int_met) a photon takes with a nm we do not find either position measured precisely and momentum uncertain or vice versa. There is no physical interaction (pi) between the particle measured and a measuring apparatus (ma). We do know that a photon did not take the other possible path through the int_met. In a nm one must know what is happening at both legs of the int_met. The same applies to positive measurements (pms) where there is a pi between the particle and the ma. For pms, one starts out in the int_met with probabilities that the photon is traveling both paths and interference in the probability distribution until a pi indicates that only one leg is involved and no interference. Always at first both paths are possible paths for the photon even if we find that only one path was taken. As we are dealing with probabilistic knowledge, one can never have a pm for one path without having a nm on the other path that the photon did not take. Bohr used the up “to escape the paradoxical necessity of concluding that the behaviour of…a photon should depend on the presence of a slit in the diaphragm through which it could be proved not to pass.”