In the double-slit experiment, the behavior of particles, such as electrons, when not observed or measured is described by their wave function, which follows the laws of quantum mechanics. The wave function represents the probability distribution of where a particle is likely to be found if a measurement is made.
When unobserved, the particles in the double-slit experiment exhibit an interference pattern. This means that the particles behave as waves and produce an alternating pattern of light and dark bands on a screen placed behind the double slits. The interference pattern arises due to the wave-like nature of particles and their ability to interfere with themselves.
Each particle's wave function passes through both slits simultaneously, creating two coherent wavefronts that interact with each other. The resulting interference pattern on the screen is a consequence of the constructive and destructive interference between these two wavefronts. This pattern indicates regions of high and low probability for the particle's detection.
It's important to note that the wave function describes the probabilistic nature of quantum particles. It represents the range of possibilities for the particle's position or other observable properties until a measurement is made. Once a measurement or observation is performed, the wave function collapses into a specific state, and the particle is observed at a particular location.
In summary, when not observed or measured in the double-slit experiment, particles behave as waves and create an interference pattern on the screen. The wave function represents the probability distribution of the particle's position, and it collapses into a specific state upon measurement or observation.