Before an observation is made, an object exists in all possible states simultaneously. To determine which state the object is in, we have to make an observation, which “collapses” the wave function, and the object goes into a definite state. The act of observation destroys the wave function, and the object now assumesa definite reality.
Michio Kaku, Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos
existence, observation, reality