I've always been confused about something -- I'd love for someone to clear up my ignorance. I understand that the position of a particle can be modeled as a wavefunction (a probability distribution, to my understanding) where we can describe the position as fundamentally random, but it takes on a value at a frequency in accordance to the distribution once it interacts with something. My question: What does it mean for it to "interact?" When two particles collide into each other to take on their "real" states, how does it know when this occurs? In my mind I am viewing it as two clouds of probability heading towards each other. Technically, the clouds are always intersecting because the wavefunction distributes itself across all space and time, right? Even if I am wrong on that point, my question is what is actually happening here when probability clouds collide. What is the mechanism that describes the actual collapse of the wavefunction from probability clouds to real states? Do they just have to take on the same values at the same time, where this becomes more and more likely as the clouds intersect more intimately? Sorry if I am not making much sense.