Consider two scenarios: Scenario 1: Single slit, single photons sent one by one. We would have a blob or column of dots. However inside this column is there an interference pattern hidden? Scenario 2: Double slit, single photons sent one by one, however we have instrumentation in place to find out which slit the photon went through. In this case there would be two columns of dots. However inside (each of) these two columns is there an interference pattern hidden? In summary: Could a single photon via a single slit still be interfering with "itself"?