electron two slit experiment with gradual "collapse"? Just read about the two slit experiment with electrons where you try to find out through which slit the electron went by "shining a light on it" (Feynman lectures on physics I-37-7). I try to summarize the statement and then have a question: When using high intensity, high frequency light, every electron going through the apparatus can be detected and assigned to one of the two slits. In this case, no interference pattern can be seen. Now the frequency of the light (not the intensity) is reduced continuously, or in sufficiently small steps for a sufficient number of experiments. Still every electron is detected, but due to the lower frequency, the resolution of the measurement of the electron's position becomes less and less accurate, making an assignment to one of the slits more and more difficult and uncertain. The more the position gets uncertain, the clearer the interference pattern appears. Now my question: Isn't the disappearance of the interference pattern usually attributed to the "collapse of the wave function"? If yes, does the above describe a "fractional" collapse, or is this a completely different process from what is usually called the "collapse of the wavefunction"? Harald.