Believe it or not, but the following fact has been demonstrated in scientific labs multiple times.
When observed, matter behaves as particles. When not observed, matter behaves as waves. How does the simple act of observing change the state of matter? How does matter know it is being observed? Nobody knows the answer to this question.In other words, reality (which, for us is formed by various spatial configurations of matter and its relation to time) may only exist only when observed. Otherwise, reality might just be a wave function of probabilities. See this video to understand this concept better.
See this video.