A central open problem of quantum physics is to reconcile theory with experience. In this work I present a framework for studying distinct modes of experience in a superposed world. A modes of experience is characterized by how the world, experiences, and options relate to each other by the perceptions, decisions, and actions, as well as by probabilistic rules encoding probabilistic or deterministic correlations among first person experiences. In a toy model, the life expectancies of beings in different candidate modes of experience are compared. It is found that the quantum mode without macroscopic superposition outlives that with macroscopic superposition and that with real amplitudes. These highlight the prospect to explain a mode of experience by its evolutionary advantages.
A central open problem of quantum physics is to reconcile theory with experience. In this work I present a framework for studying distinct modes of experience in a superposed world. A modes of experience is characterized by how the world, experiences, and options relate to each other by the perceptions, decisions, and actions, as well as by probabilistic rules encoding probabilistic or deterministic correlations among first person experiences. In a toy model, the life expectancies of beings in different candidate modes of experience are compared. It is found that the quantum mode without macroscopic superposition outlives that with macroscopic superposition and that with real amplitudes. These highlight the prospect to explain a mode of experience by its evolutionary advantages.
Quantum mechanics has achieved unparalleled success as an operational theory, describing a wide range of experiments to remarkable accuracy. However, the physical foundations on which it rests remain as puzzling as they were a century ago, and a concise statement of the physical principles that underlie quantum mechanics is still outstanding. One promising approach holds that these principles should be formulated in terms of information, since many of the counter-intuitive effects in quantum theory concern questions such as what one can know about a quantum system and how the information encoded therein can be processed and distributed between parties. Another challenging feature of quantum theory is its incompatibility with the other cornerstone of modern physics, general relativity. In order to reconcile the two, one must identify and retain only the essential concepts and principles of each theory, and in the case of general relativity, causality has been identified as such a concept. This raises the question of how our classical understanding of causality must change when quantum theory is taken into account. In order to address these questions about information, knowledge and causality, I turn to the framework of causal models. In classical statistics, causal models explain the relations among a set of variables in terms of causal influences, which makes them a powerful tool for structuring our knowledge about complex systems and developing strategies for interacting with them. More importantly, the framework provides the conceptual underpinnings and mathematical methods for addressing questions about causation, information and knowledge in a rigorous manner. In this thesis, I develop a version of the classical causal models framework that is compatible with quantum theory and explore its physical implications. \n \n \nA first step is to define quantum versions of fundamental elements such as variables, conditionals and belief propagation rules. This allows one to consider the question of what one can come to know about a quantum variable from the point of view of causal modelling. The conditionals relating quantum variables are found to have a richer structure than their classical counterparts, which can be exploited for the task of discerning causal relations given limited data -- a central problem in classical causal modelling. The mathematical properties of quantum conditionals also establish a correspondence between various classes of two-party correlations, such as bound and distillable entanglement, and the types of causal structures that can give rise to them, which may become a useful tool for entanglement theory and quantum information processing. In the context of open quantum systems dynamics, quantum causal models provide a clear physical explanation of not completely positive maps and, more broadly, of non-Markovian quantum dynamics. Finally, I consider the possibility of non-classical effects in the way that different causal mechanisms are combined -- that is, non-classical causal structures. For the simple case of two causally ordered variables, I propose indicators that witness different classes of combinations of causal mechanisms, including a non-classical mixture, and describe an experiment realizing examples of the different classes. \n \n \nAs these results illustrate, the framework of quantum causal models provides both greater conceptual clarity and a comprehensive mathematical formalism for studying a diverse set of problems, ranging from foundational questions to applications in open systems dynamics and the exploration of non-classical causal structures, which are likely to feature in a future theory of quantum gravity. The material presented in this thesis is intended as a foundation and inspiration for further applications of quantum causal models.
Human beings do not observe world from outside, but rather are fully embedded in it. The sciences, however, often give observer both a god's eye perspective and substantial a~priori knowledge. Motivated by W. Ross Ashby's statement, the theory of Black Box is merely theory of real objects or systems, when close attention is given to question, relating object and observer, about what information comes from object, and how it is obtained (Introduction to Cybernetics, 1956, p. 110), I develop here an alternate picture of world as a black box to which observer is coupled. Within this framework I prove purely-classical analogs of no-go theorems of quantum theory. Focussing on question of identifying macroscopic objects, such as laboratory apparatus or even other observers, I show that standard quantum formalism of superposition is required to adequately represent classical information that an observer can obtain. I relate these results to supporting considerations from evolutionary biology, cognitive and developmental psychology, and artificial intelligence.
This is an attempt to reconcile the formalisms of quantum mechanics with ordinary macroscopic experience. Thus the formal superposition of alternative physical states is interpreted as an actual superposition of differing “copies” of the same object or objects. Chance events usually regarded as mutually exclusive are here assumed to have simultaneous effects on different copies of the same system, including its human observers. In this way, initially superposed copies become separated and undergo differential changes. Reconvergence of differentiated copies gives rise to familiar diffraction phenomena. Specific physical examples and human experiences are treated, and the Schrödinger equation is derived.
After a summary of Bohr's views and their relation to Kant's theory of science, two fruitless lines of attack on the measurement problem are discussed: the way of the psi-ontologist and the way of the QBist. In the remainder of the paper the following results are obtained. (i) Because the testable correlations between outcomes of measurements of macroscopic positions are consistent with both the classical and the quantum laws, there is no conflict between the superposition principle and the existence of measurement outcomes. (ii) Intrinsically, each fundamental particle is numerically identical with every other fundamental particle. What presents itself here and now with these properties and what presents itself there and then with those properties is one and the same entity, herein called "Being." (iii) The distinction between a classical domain and a quantum domain is essentially a distinction between the manifested world and its manifestation. By entering into reflexive spatial relations, Being gives rise to (a) what looks like a multiplicity of relata if the reflexive quality of the relations is ignored, and (b) what looks like a substantial expanse if the spatial quality of the relations is reified. (iv) The reason why quantum mechanics is a calculus of correlations between measurement outcomes is that it concerns the progressive realization of distinguishable objects and distinguishable regions of space. (v) The key to the relation between quantum mechanics and experience is that Being does not simply manifest the world, Being manifests the world to itself. It is at once the single substance by which the world exists and the ultimate self or subject for which it exists. The question how we are related to this ultimate self or subject is discussed.
I take a pragmatist perspective on quantum theory. This is not a view of the world described by quantum theory. In this view quantum theory itself does not describe the physical world, nor our observatons, experiences or opinions of it. Instead, the theory offers reliable advice on when to expect an event of one kind or another, and on how strongly to expect each possible outcome of that event. The actual outcome is a perspectival fact: a fact relative to a physical context of assessment. Measurement outcomes and quantum states are both perspectival. By noticing that each must be relativized to an appropriate physical context one can resolve the measurement problem and the problem of nonlocal action. But if the outcome of a quantum measurement is not an absolute fact, then why shoud the statistics of such outcomes give us any objective reason to accept quantum theory? One can describe extensions of the scenario of Wigner's friend in which a statement expressing the outcome of a quantum measurement would be true relative to one such context but not relative to another. However, physical conditions in our world prevent us from realizing such scenarios. Since the outcome of every actual quantum measurement is certified at what is essentially a single context of assessment, the outcome relative to that context is an objective fact in the only sense that matters for science. We should accept quantum theory because the statistics these outcomes display are just those it leads us to expect.
This work presents an option to unite different perspectives of reality. Through literature review and considerations of visible manifestation of light and other physical effects, the author evaluates if quantum effect shows up in our daily life. Reality is an overlap of waves which our brain utilizes to produce individual perception. It is not so bizarre to consider the interference pattern of particles if we characterize the visual experience as a momentary photograph of that wave. Science is multi-disciplinary, so we attempt to reconcile diverse areas of knowledge.