In philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible. A still broader definition includes everything that has existed, exists, or will exist. Reality is often contrasted with what is imaginary, delusional, (only) in the mind, dreams, what is abstract, what is false, or what is fictional. The truth refers to what is real, while falsity refers to what is not. Fictions are considered not real. Reality can be defined in a way that links it to world views or parts of them. Reality is the totality of all things, structures (actual and conceptual), events (past and present) and phenomena, whether observable or not. It is what a world view , whether it be based on individual or shared human experiences, ultimately attempts to describe or build a map. The main two categories in science to understanding consciousness is that of general relativity and quantum mechanics. One of the unsolved problems in physics is general relativity and quantum mechanics are hard to unify. Quantum mechanics involves quantum superpositions, which are not perceived by observers, some interpretations of quantum mechanics place conscious observers in a special position. The founders of quantum mechanics debated the role of the observer, and of them, Wolfgang Pauli and Werner Heisenberg believed that it was the observation that produced collapse. This point of view, which was never fully endorsed by Albert Einstein. Quantum theory offers a complete description of nature, albeit one that is simply ill suited for everyday experiences – which are better described by classical mechanics and probability. “Schrödinger’s cat” thought experiment proposed that the consciousness of an observer is the demarcation line which precipitates collapse of the wave function, independent of any realist interpretation. Commonly known as “consciousness causes collapse”, this interpretation of quantum mechanics states that observation by a conscious observer is what makes the wave function collapse. Quantum physics tries to describe a theory that would unify or explain through a single model the theories of all fundamental interactions and of all particles of nature: general relativity for gravitation, and the standard model of elementary particle physics – which includes quantum mechanics – for electromagnetism, the two nuclear interactions, and the known elementary particles. Current candidates for a “Theory of everything” include string theory, M theory, and loop quantum gravity.