I've been exposed to two different interpretations of the uncertainty principle. 1) If an electron is in a certain state, a measurement of its position will yield a definite result. However, if after the measurement the electron could be returned to the same state, then a repeated measurement of its position will yield a different answer. Same holds for measurements of momentum. However, the standard deviation of the distribution for positions * the standard deviation for the distribution for momentum will always be greater than a certain constant. 2) Measurements are fuzzy. Measurements of, say, position will never yield a definite result, unless the momentum becomes completely unknown. Which one is right?