In quantum mechanics, the wave function is a mathematical description of a particle or a physical system. It contains all the information about the particle's possible states, such as its position, momentum, and energy. The wave function is typically represented by the Greek letter psi (Ψ).
The wave function itself is a complex-valued function that obeys the Schrödinger equation, which describes the evolution of quantum systems over time. It is a fundamental concept in quantum mechanics and provides a probabilistic interpretation of the behavior of particles at the microscopic level.
When a measurement is made on a quantum system, such as measuring the position or momentum of a particle, the wave function "collapses" or "reduces" to a specific state. The collapse of the wave function is a non-deterministic process, meaning that the outcome of the measurement cannot be predicted with certainty. Instead, the collapse occurs probabilistically, and the outcome is determined by the probabilities encoded in the wave function.
Once the wave function collapses, the particle is found in one of its possible states corresponding to the measured quantity. The other possible states that were initially described by the wave function no longer hold true, and their probabilities go to zero. This collapse reflects our knowledge about the particle becoming definite and removes the superposition of multiple states. The specific state the particle collapses into depends on the particular measurement that was performed.
It's important to note that the interpretation and understanding of the collapse of the wave function are still topics of debate and different interpretations exist in quantum mechanics, such as the Copenhagen interpretation, many-worlds interpretation, and objective collapse theories. These interpretations offer different perspectives on the nature of the collapse and the fate of the other possible states.