If we have a kilometer long million slit light source and make an observation on a slit at one of the ends, will the interference pattern fully collapse or partially collapse? is there any delay in the propagation of the collapse or is the collapse instant?
Link to multiple slits.
Additional information. I am thinking that if Alice is at one end, point A and is looking at the pattern on the wall from the million slits. Bob is at the other end a kilometer away at point B. Bob then makes an observation to detect if a photon is going through a slit. Wouln't Alice see the pattern on the wall disappear?
My understanding of how this is not faster than light in the 2 slit experiment is because the change in light travels from the slit to the wall at c after the instant collapse. In the multiple slit though the collapse travels a lot further instantly and then the change in light travels at c from the slits to the wall. For Alice that is. Where is my mistake?