I have 2 questions 1. I'm telling a friend that in the double slit experiment.. the electron has no trajectories between the emission and detection. But she commented the initial emission has trajectory. Is this correct? What is the term for this situation of the initial emission of the electron? 2. In the detection, how do you change the observable from position to let's say energy. Or what kind of detector do you have to put so it won't measure the position of the particle but some other observable (and what are they?) Thank you.