Physicians define death as the irreversible breakdown of all brain-functions including brain-stem. By irreversible they mean a damage that is beyond the human capacity to restore the patient's healthy state. In the same line I propose to complete the definition of quantum physics [1] by Principle D (Detection): Detection outcomes (like death) are ordinarily irreversible and observerindependent. It is then argued that this principle excludes generalization of quantum superposition to visible objects bearing observer-dependent outcomes. However this exclusion is not absolute: It rather means that "Schrödinger's cat" and "Wigner's friend" should be considered "miracle" narratives beyond the domain of science.