In quantum physics, the transition from possibilities to certainty occurs when a measurement or observation is made on a quantum system. Until a measurement is made, the system exists in a superposition of multiple possible states, each with an associated probability. However, upon measurement, the wavefunction describing the system collapses, and the system is found in a specific state corresponding to the measurement outcome.
The collapse of the wavefunction is a fundamental aspect of quantum mechanics and is often referred to as the measurement problem. It remains a topic of philosophical and interpretational debate. Various interpretations of quantum mechanics provide different explanations for when and how the collapse occurs.
According to the Copenhagen interpretation, which is widely accepted, the collapse happens instantaneously upon measurement. The act of observation triggers the collapse, and the system is projected into one of the possible states with probabilities given by the wavefunction. This collapse is inherently probabilistic, as it is not possible to predict with certainty which state the system will collapse into for a specific measurement.
It is important to note that until a measurement is made, the possibilities described by the wavefunction can interfere and exhibit wave-like behavior. This interference pattern can be observed in experiments such as the famous double-slit experiment, where particles exhibit both wave-like and particle-like characteristics until a measurement is made to determine their path.
In summary, in quantum physics, possibilities become certain through the process of measurement or observation, which causes the collapse of the wavefunction and determines the specific state of the system. Prior to measurement, the system exists in a superposition of multiple possible states, each with associated probabilities.