The Multiverse
So we have to come to a deeper understanding of how to explain what is going on in this double state experiment. Because if we fire either a photon or an electron at that double-slit apparatus, and we put a detector at either of those slits, then we will detect a particle.
So we can detect that we fired a particle, we can detect that a particle is going through those slits, and we can detect a particle at the projection screen as well. When you do this experiment in the laboratory using electrons, you can see the dots where the electrons strike, hitting the screen. But you don't get a simple pattern that you would expect if you're firing cannon balls at a wall where there are two holes in the wall through which the cannonballs can go.
You would expect that all the cannonballs are going to go through those two holes and land in one of two positions behind the wall. But with particles at the quantum level, that's not what happens. Something is going on, and the only explanation is that when we fire a photon, there's the photon that we can see in our universe, but there's also photons in other universes passing through the apparatus that we cannot see.
And these photons are able to interact with the photon that we are able to detect. This is where the concept of interference comes in. Interference is an old concept in physics; it goes back to waves. Waves certainly interfere, but we need to understand the way in which particles can interfere one with another.
Particles that we can observe and particles that we can only assume to observe given these experiments. And this is why we are forced into acknowledging the existence of these other particles, and not only these other particles, but other universes in which these particles exist.