Niels Bohr's theory on the collapse of wave functions is an interpretation of quantum mechanics known as the Copenhagen interpretation. This interpretation was developed in the 1920s and played a significant role in shaping our understanding of quantum physics.
In Bohr's interpretation, the wave function represents the probability distribution of finding a particle in different states. It describes the "superposition" of all possible states that a particle can exist in simultaneously. However, when a measurement or observation is made on the particle, the wave function collapses instantaneously into a single state corresponding to the observed value.
Bohr argued that the act of measurement disturbs the system being measured, and the observer interacts with the system in a way that determines the outcome of the measurement. This interaction causes the wave function to collapse, and the particle takes on a definite value.
According to the Copenhagen interpretation, the collapse of the wave function is a fundamental and irreducible aspect of quantum mechanics. It introduces an element of unpredictability into the behavior of quantum systems, as the outcome of a measurement cannot be precisely determined beforehand. Instead, the collapse occurs probabilistically, with the probability of obtaining a particular outcome determined by the squared magnitude of the corresponding amplitude in the wave function.
Bohr emphasized that the wave function represents our knowledge and information about a system rather than a physical reality. He viewed it as a mathematical tool for calculating probabilities, but not a complete description of the underlying reality. Bohr believed that the concepts of classical physics, which rely on deterministic and objective properties, break down at the quantum level.
It's worth noting that the Copenhagen interpretation has been a subject of debate and alternative interpretations of quantum mechanics have also emerged. However, Bohr's ideas on the collapse of wave functions and the role of measurement continue to be influential in the field of quantum physics.