[alphydan]

That is not an answer to his objection.

If you follow the equations of the wave packet of the particle arriving to the wall (or CCD) detector, you then need to solve the equation of the interaction of the particle + all the particles in the wall or the CCD. The challenge of the collapse is that simulating anything beyond a few dozen quantum particles is too demanding. Mathematical models that simulate millions of particles need to make assumptions (typically they are too hot, too cold, too strongly bound, so you can ignore most effects - think 1D Ising model, Bose-Einstein Condensates, Photon gases, etc). But the full description of a particle + all particles in a detector still escapes us.

Therefore the transition between: superposition of paths -> particle lands at specific points has never been truly explored. The best description currently involves decoherence. Many theorems have been proven (and experiments done) in that area. The gist is that as you add particles to a system (2, 3, 4, 5, 10, ...) the superposition effects slowly cancel each other out. Another angle is the monogamy of entanglement (the more particles are entangled, the weaker the entanglement between any 2 particles). The idea of decoherence is that as things get larger, the weird effects of quantum physics become more "dilute". However, going from double slit to macroscopic reading still has many assumptions along the way.

Take the above explanation with a grain of salt (as I have tried to make it accessible).