Single photon, double slit question If photons are fired conitnuosly one at a time through the double slits is the statistical outcome going through each slit 50%?
 A: The key feature of the double slit experiment is that the light passes through both slits at the same time. It does not go through one slit or the other but instead passes through both.
This happens because unlike macroscopic objects like baseballs quantum objects do not have a position. They are fuzzy objects that are spread out over a region of space. The double slit experiment only works when the photons are delocalised enough that their spatial extent covers both slits.
A: Yes.
You actually state it quite well: the statistical outcome, if you were to measure the path of the photon (or any other quantum particle, for all that matters), would be 50% for each slit. It would ruin the interference pattern on the screen, though.
The quantum description in absence of measurement would be to say that the statistical amplitude is the same for each slit.
Formally, the difference between both situation corresponds to the loss of coherences due to the measurement.
A: The answer is no. The information of the photon spreads outward everywhere. (The wave function evolves spreading out, so it goes through both slits, no 50/50 chance stuff here.) Once it interacts (wavefunction of photon becomes significantly non-zero at the surface/detector) with the surface/detector, the wave function evolves/collapses to one of its position eigenvalues.
