The behavior you're referring to, where two particles can occupy the same place at the same time, is a fundamental concept in quantum mechanics called "quantum superposition." It is different from the classical notion of objects occupying distinct positions.
In quantum mechanics, particles are described by wavefunctions, which are mathematical representations that encode the probabilities of finding a particle in different states or positions. According to the principles of superposition, a particle can exist in a combination or superposition of multiple states simultaneously.
For example, consider a hypothetical experiment with two particles, such as electrons, called particle A and particle B. Each particle has its own wavefunction, and initially, let's assume they are well-separated. If we bring particle A and particle B close together, their wavefunctions can interact, resulting in entanglement.
Entanglement is a phenomenon where the wavefunctions of two or more particles become correlated, so that the state of one particle cannot be described independently of the state of the other. When particles are entangled, their individual wavefunctions are no longer separable, and they form a joint or composite wavefunction.
In some cases, the composite wavefunction can have properties that allow the particles to exhibit a form of spatial overlap. This means that the position of one particle is not well-defined or localized, but instead, it exists in a superposition of possible positions. The same applies to the other entangled particle. This doesn't mean that the particles physically occupy the exact same space, but rather that their wavefunctions are entangled in a way that their positions are highly correlated and uncertain until a measurement is made.
However, when a measurement is performed to determine the position of one particle, the superposition "collapses" into a specific outcome, and the wavefunctions of the particles become localized or separated. This collapse leads to one of the particles taking on a definite position, and the other particle instantaneously assumes a correlated position due to the entanglement.
It's important to note that the concept of particles being in the same place at the same time is more accurately described in terms of their wavefunctions and the probabilistic nature of quantum mechanics. Quantum superposition and entanglement are fundamental aspects of the quantum world and have been experimentally verified through numerous experiments and observations.