The behavior of a single photon in the double-slit experiment is often described in terms of wave-particle duality, which can lead to some conceptual challenges. When a single photon is sent toward a double-slit apparatus, it can exhibit interference patterns characteristic of wave-like behavior.
According to the standard interpretation of quantum mechanics, the photon does not go through both slits simultaneously as classical particles would. Instead, it exists in a superposition of states, where it is in a combination of possibilities. This superposition includes the possibility of passing through both slits, and it's this superposition that allows for interference effects to occur.
When the photon interacts with the detection screen, its wavefunction collapses to a specific location, and it appears as if the photon went through one of the slits. The interference pattern emerges when many photons are sent through the apparatus, and their individual probabilities interfere constructively or destructively.
It is important to note that the concept of a photon simultaneously going through both slits is a way of describing the behavior mathematically using wave-particle duality. The underlying reality is more nuanced and requires a quantum mechanical framework to fully comprehend. The wave-particle duality is a manifestation of the probabilistic nature of quantum mechanics, where particles can exhibit wave-like or particle-like properties depending on the experimental setup and observation.