The cliché has it that the Copenhagen interpretation demands adherence without deep enquiry. That does physics a disservice
Collapse Theories
Quantum mechanics, with its revolutionary implications, has posedinnumerable problems to philosophers of science. In particular, it hassuggested reconsidering basic concepts such as the existence of aworld that is, at least to some extent, independent of the observer,the possibility of getting reliable and objective knowledge about it,and the possibility of taking (under appropriate circumstances) atleast some properties to be objectively possessed by physical systems.It has also raised many others questions which are well known to thoseinvolved in the debate on the interpretation of this pillar of modernscience. One can argue that most of the problems are not only due tothe intrinsic revolutionary nature of the phenomena which have led tothe development of the theory. They are also related to the fact that,in its standard formulation and interpretation, quantum mechanics is atheory which is excellent (in fact it has an unprecedented success inthe history of science) in telling us everything about what weobserve, but it meets with serious difficulties in telling uswhat there is. We are making here specific reference to thecentral problem of the theory, usually referred to as themeasurement problem, which is accompanying quantum theory sinceits birth. It is just one of the many attempts to overcome thedifficulties posed by this problem that has led to the development ofCollapse Theories, i.e., to the Dynamical ReductionProgram (DRP). As we shall see, this approach consists inaccepting that the dynamical equation of the standard theory should bemodified by the addition of stochastic and nonlinear terms. The nicefact is that the resulting theory is capable, on the basis of a singledynamics which is assumed to govern all natural processes, to accountat the same time for all well-established facts about microscopicsystems as described by the standard theory, as well as for theso-called postulate of wave packet reduction (WPR), which accompaniesthe interaction of a microscopic system with a measuring device. As iswell known, such a postulate is assumed in the standard scheme just inorder to guarantee that measurements have outcomes but, as weshall discuss below, it meets with insurmountable difficulties if onetries to derive it by assuming the measurement itself to be a processgoverned by the linear laws of the theory. Finally, the collapsetheories account in a completely satisfactory way for the classicalbehavior of macroscopic systems.
Spirits and the incompleteness of physics
Complexity, renormalization, and the spirits beyond the horizon of theory
The Kochen-Specker Theorem
The Kochen-Specker theorem is an important and subtle topic in the foundations of quantum mechanics (QM). The theorem demonstrates the impossibility of a certain type of interpretation of QM in terms of hidden variables (HV) that naturally suggests itself when one begins to consider the project of interpretating QM.We here present the theorem/argument and the foundational discussion surrounding it at different levels. The reader looking for a quick overview should read the following sections and subsections: 1, 2, 3.1, 3.2, 4, and 6. Those who read the whole entry will find proofs of some non-trivial claims in supplementary documents.
Putting Paradoxes to Work: Contextuality in Measurement-Based Quantum Computation
We describe a joint cohomological framework for measurement-based quantum computation (MBQC) and the corresponding contextuality proofs. The central object in this framework is an element $$[\beta _\Psi ]$$[βΨ]in the second cohomology group of the chain complex describing a given MBQC. $$[\beta _\Psi ]$$[βΨ]contains the function computed therein up to gauge equivalence, and at the same time is a contextuality witness. The present cohomological description only applies to temporally flat MBQCs, and we outline an approach for extending it to the temporally ordered case.
Jacob Barandes - “A Deflationary Account of Quantum Theory & Implications for the Complex Numbers”
The Consistent Histories Approach to Quantum Mechanics
The consistent histories, also known as decoherent histories, approachto quantum interpretation is broadly compatible with standard quantummechanics as found in textbooks. However, the concept ofmeasurement by which probabilities are introduced in standardquantum theory no longer plays a fundamental role. Instead,all quantum time dependence is probabilistic (stochastic),with probabilities given by the Born rule or its extensions. Byrequiring that the description of a quantum system be carried outusing a well-defined probabilistic sample space (called a“framework”) this approach resolves many well-knownquantum paradoxes of quantum foundations. In particular, quantummechanics is local and consistent with special relativity. Classicalmechanics emerges as a useful approximation to the more fundamentalquantum mechanics under suitable conditions. The price to be paid forthis is a set of rules for reasoning resembling, but very much simplerthan, those of quantum logic. An important philosophical implicationis the absence of a single universally-true state of affairs at eachinstant of time. However, there is a correspondence limit in which thenew quantum logic becomes standard logic in the macroscopic world ofeveryday experience, and the laws of classical mechanics emerge as agood approximation to an underlying, and in principle more exact,quantum description.
Jacob Barandes | Quantum Theory as a New Kind of Stochastic Process
Jacob Barandes | Quantum Theory as a New Kind of Stochastic Process
QBism: Quantum Theory as a Hero's Handbook
This paper represents an elaboration of the lectures delivered by one of us (CAF) during "Course 197 -- Foundations of Quantum Physics" at the International School of Physics "Enrico Fermi" in Varenna, Italy, July 2016. Much of the material for it is drawn from arXiv:1003.5209, arXiv:1401.7254, and arXiv:1405.2390. However there are substantial additions of original material in Sections 4, 7, 8 and 9, along with clarifications and expansions of the older content throughout. Topics include the meaning of subjective probability; no-cloning, teleportation, and quantum tomography from the subjectivist Bayesian perspective; the message QBism receives from Bell inequality violations (namely, that nature is creative); the import of symmetric informationally complete (SIC) quantum measurements for the technical side of QBism; quantum cosmology QBist-style; and a potential meaning for the holographic principle within QBism.
More on whether useful quantum computing is “imminent”
These days, the most common question I get goes something like this: A decade ago, you told people that scalable quantum computing wasn’t imminent. Now, though, you claim it plausibly is immi…
Illusions of Understanding in the Sciences
Scientists seek to understand the causes of observed phenomena. Beliefs that they have succeeded are based on understanding that is rarely or possibly never complete, and varies in depth and quality. Most often scientists believe they understand more than they do, making their belief an illusion. This illusion then persists in explanations scientists provide in print, in talks, or in discussions. The illusion that a scientist has a valid and complete explanation tends to be magnified when the data are well described by mathematical and computer simulation models due to the precision of such models and their ability to predict well; prediction does not imply causality, but gives the illusion that it does. The first part of this essay supports the case for the universality of partial and incomplete levels of understanding by showing the difficulty of reaching a deep level of understanding for even a simple analysis and model that most scientists use and believe they understand: linear regression. The second part highlights some implications of the existence of many levels of understanding and explanation, and their use by scientists for design, testing, analysis, and theory development. It discusses the way that deduction and induction depend on the levels of understanding and the implications of the illusion that a scientist’s understanding is deep. It makes a case that the many incomplete levels of understanding affect, often unwittingly, the ways scientists design experiments, test theories, comprehend, communicate, and teach.
The hard problem of consciousness is a distraction from the real one | Aeon Essays
It looks like scientists and philosophers might have made consciousness far more mysterious than it needs to be
Alexander Lerchner, The Abstraction Fallacy: Why AI Can Simulate But Not Instantiate Consciousness - PhilArchive
Computational functionalism dominates current debates on AI consciousness. This is the hypothesis that subjective experience emerges entirely from abstract causal topology, regardless of the underlying physical substrate. We argue this view ...
Alexander Lerchner, The Abstraction Fallacy: Why AI Can Simulate But Not Instantiate Consciousness - PhilPapers
Computational functionalism dominates current debates on AI consciousness. This is the hypothesis that subjective experience emerges entirely from abstract causal topology, regardless of the underlying physical substrate. We argue this view ...
The cell membrane as the ‘missing link’ for the evolution of consciousness
While Prof. Torday agrees with Federico Faggin that quantum mechanics is salient to consciousness, he maintains that the role of the cell membrane—which separates an organism from its environment—is key to the selective assimilation or mirroring of the quantum properties of the cosmos into the differentiated consciousness of the organism. This essay is short, dense, and may be difficult to unpack. But it handsomely rewards the effort of the patient and determined reader. The many literature citations in the essay also provide rich ground for further exploration.
