My brain is in great pain from reading Greene's 'Fabric o/t Cosmos'. I'm currently on p.197 (Chapter 7: Time and the Quantum - Shaping the Past). He's got the delayed choice setup rigged so that photons with 'which-path' info and no 'which-path' info are hitting the same screen. He says that if you examine *all* the data from all photons, you see no interference pattern - quote" ...not the slightest hint of an interference pattern...", but if you examine a subset of that data, corresponding to the photons that had no which-path data available, you see an interference pattern. He goes further to suggest that if you could have the two types of points coloured-coded, a colour-blind observer would see no pattern. So, here's my question: If half the photons are lining up in an interference pattern, and the sum total have no pattern, that must mean that the remaining photons are impacting preferentially in places where the interference patterns produce dark bands. Basically, they would have to produce a sort of inverse pattern to cancel out the first pattern. (See attached diagram) (It's something often experienced when spray painting. If you draw some lines (a pattern) on a wall, you can't then expect that a second spraying in a random (no pattern) coverage will cancel it out - you would merely get the sum of the two sprayings. To actually cancel your design out, you would have to preferentially fill in the blank areas until everything was even again.) Am I misunderstanding? What if you heavily weighted the experiment to produce 99% photons with no 'which-path' data? Would the sum total of the 99% patterned and the 1% unpatterned photons still show no discernible pattern? Ow ow.