simulating telescope images

John Peterson (Purdue) is one of the principals in the LSST image simulation project. This project is insane, in that it simulates the images by laying down every single photon, from source through atmosphere, optics, and CCD. I spent a large part of today talking to him about all this, including the issue that it is hard (obviously) to see diffraction effects when you treat the light as being in the form of photons; there are some beautiful approximate methods for bridging the wave–particle duality. This is a nice problem to think about: How do you properly do simulations of a telescope, including all diffraction and refraction effects, without collapsing the wave function at the wrong time?