I've been reading up a lot on the double slit experiment recently (and I'm no physicist at all). Although I haven't really seen the experiment done with my own eyes, from the demonstrations on youtube it seems as though the pattern when shining a laser through the slits is constant and solid. If this was really probability would a laser shining through onto a screen not be like an extremely fast animated version of watching the single photos building up (but disappearing as fast as they appear)? So would this not make the result appear to flicker...vary in brightness on each line? Unless it is not truly probability and the result is a guaranteed pattern after X amount of photons? Maybe it does flicker if you have seen it yourself but I have yet to get the chance.