I was watching this simulation of two quantum wave packets colliding in a box:
The wave function gets arbitrarily delocalized as time goes on until you have almost an equal probability of finding the two particles anywhere in the box. This would mean that the particles are "everywhere" in the box and the place where they would "appear" upon measurement would be almost random.
Do real particles traveling in interstellar space without interacting much at all with anything get smeared out in this way? If so how we can form images of extremely far away objects? It seems as if any photon emitted from a star would be extremely delocalized by the time the wave packet reaches earth, even if it has an initially well defined direction and position when emitted. The probability of finding it at any given point on the expanding "sphere of influence" of the wave packet would be extremely small.
Also, how most of the particles in our "real" world seem to be always very localized? I mean, my body doesn't dissolve as time goes on. I can imagine these reasons of why this happens in practice:
Because interactions between individual particles with large systems maintains them localized. Those interactions would be more similar to "measurements" than the interaction seen on the simulation and so their wave functions would be continuously collapsing.
Most of my particles are "locked" into a kind of potential from which they can't escape like the one on the simulation.
A combination of both.
Which one is correct, is there another explanation?