The phenomenon you are referring to is the famous double-slit experiment, which demonstrates the wave-particle duality of matter. In this experiment, a beam of particles, such as electrons, is directed at a barrier with two closely spaced slits. The particles can behave as both waves and particles simultaneously.
When electrons pass through the double slits, they exhibit an interference pattern on a screen placed behind the barrier. This pattern arises due to the wave nature of electrons interfering with themselves as they pass through the slits. Interference occurs when two or more waves overlap, leading to constructive or destructive interference at different locations.
To detect the passage of electrons through the double slits, a detector, such as a photographic plate or a sensitive electronic device, is placed behind the slits. This detector records the position of the electrons when they arrive. By collecting a large number of electron impacts over time, the interference pattern emerges, revealing the wave-like behavior of the particles.
It's important to note that the act of detection itself can disrupt the interference pattern. The detection process typically involves interacting with the electron, which disturbs its wavefunction and collapses it into a definite position. This collapse destroys the interference pattern and results in a pattern similar to what would be observed if electrons were simply particles.
The double-slit experiment challenges our intuitive understanding of particles and waves. The behavior of particles at the quantum level is inherently probabilistic and described by a mathematical framework called quantum mechanics. This experiment highlights the strange and fascinating nature of quantum mechanics and continues to be a subject of intense study and interpretation among physicists.