>[!abstract] >In quantum mechanics, the measurement problem is the problem of definite outcomes: quantum systems have superpositions but quantum measurements only give one definite result. > >The wave function in quantum mechanics evolves deterministically according to the [[Schrödinger equation]] as a linear superposition of different states. However, actual measurements always find the physical system in a definite state. Any future evolution of the wave function is based on the state the system was discovered to be in when the measurement was made, meaning that the measurement "did something" to the system that is not obviously a consequence of Schrödinger evolution. The measurement problem is describing what that "something" is, how a superposition of many possible values becomes a single measured value. ("Measurement problem", 2025). ## References - Measurement problem. (2025, February 15). In *Wikipedia*. https://en.wikipedia.org/w/index.php?title=Measurement_problem&oldid=1260881809 ## Related - [[Schrödinger's cat]]