Apparently it should not just work with light, a wave that goes on.
A gas is not, a liquid, and a solid is not thought to be a wave. So how is the double-slit experiment done with molecules that do not have a wave function?
However, you're stopping at the double-slit experiment. The other quantum mechanics experiment is the 58 atom molecule can be in either Box A or Box B.
When you open Box A and it is there, it shoots to the projector screen. When opening Box B it is not there.
When you open Box A and it is not there, you open Box B and it shoots to the projector screen.
When you open Box A and Box B at the same time, it cannot shoot to the same place on the projector screen. This illustrates that the molecule was in both boxes before shooting to the projector screen.
The third experiment is that you have two molecules: one with 58 atoms and one with 114 atoms. Are both atoms in Box A or Box B or is the couple of atoms distributed in both boxes?
All possibilities exist before the observation.