A central problem in modern physics is the interpretation of results obtained in the classic double-slit experiment. The question of how particles sometimes act as waves and sometimes not is still unanswered despite much effort by physicists. In recent years, the double-slit experiment has been successfully performed using not only photons or electrons but also molecules, discrediting the traditional Copenhagen interpretation. My hypothesis is based on pilot wave theory, adding that space-time is waving around the particles depending on their energy and mass, similarly to Einstein’s theory of general relativity. John Archibald Wheeler’s words turns out to be true again: „Matter tells space-time how to curve; space-time tells matter how to move”. I believe that the problem of observation in the well-known double-slit experiment can be thought of as a physical version of the Monty Hall problem, so it does not belong to quantum mechanics as much as it does to probability theory.