Quantum Mechanics, Misc

We study the conservation of energy, or lack thereof, when measurements are performed in quantum mechanics. The expectation value of the Hamiltonian of a system changes when wave functions collapse in accordance with the standard textbook treatment of quantum measurement, but one might imagine that the change in energy is compensated by the measuring apparatus or environment. We show that this is not true; the change in the energy of a state after measurement can be arbitrarily large, independent of the (...) physical measurement process. In Everettian quantum theory, while the expectation value of the Hamiltonian is conserved for the wave function of the universe, it is not constant within individual worlds. It should therefore be possible to experimentally measure violations of conservation of energy, and we suggest an experimental protocol for doing so. (shrink)

I offer an account of how the quantum theory we have helps us explain so much. The account depends on a pragmatist interpretation of the theory: this takes a quantum state to serve as a source of sound advice to physically situated agents on the content and appropriate degree of belief about matters concerning which they are currently inevitably ignorant. The general account of how to use quantum states and probabilities to explain otherwise puzzling regularities is then illustrated by showing (...) how we can explain single-particle interference phenomena, the stability of matter, and interference of Bose–Einstein condensates. Finally, I note some open problems and relate this account to alternative approaches to explanation that emphasize the importance of causation, of unification, and of structure. 1 Introduction2 Two Requirements on Explanations in Physics3 What We Can use Quantum Theory to Explain4 The Function of Quantum States and Born Probabilities5 How These Functions Contribute to the Explanatory Task6 Example One: Single-Particle Interference7 Example Two: Explanation of the Stability of Matter8 Example Three: Bose Condensation9 Conclusion. (shrink)

This paper is about Ionicioiu and Terno's paper (2011) about wave-particle duality and my EDWs pperspective (from 2005, 2006, 2008, 2010, 2011, 2014).

Here P is the density operator of the system under consideration, and σ ± and σ 3 are the usual Pauli matrices, acting on atom i whose states are |1 > or |0 >, representing, respectively, the atom being in an excited state or in the ground state. B and C are appropriate decay constants and s has been called the pumping parameter [1]. It varies from s = 0 for pure damping to s = 1 for full laser action. (...) To solve the corresponding quantum master equations, three approaches have been taken: First, one focuses on the case of one atom. Second, one truncates eq. (1) and derives semi-classical models. Third, one employs numerical simulation methods such as the quantum trajectory method. While the latter method is very popular, it should be noted that the numerical complexity of the problem increases exponentially with the number of atoms, and so numerical methods soon become unfeasible. (shrink)

The potential for scalable quantum computing depends on the viability of fault tolerance and quantum error correction, by which the entropy of environmental noise is removed during a quantum computation to maintain the physical reversibility of the computer’s logical qubits. However, the theory underlying quantum error correction applies a linguistic double standard to the words “noise” and “measurement” by treating environmental interactions during a quantum computation as inherently reversible, and environmental interactions at the end of a quantum computation as irreversible (...) measurements. Specifically, quantum error correction theory models noise as interactions that are uncorrelated or that result in correlations that decay in space and/or time, thus embedding no permanent information to the environment. I challenge this assumption both on logical grounds and by discussing a hypothetical quantum computer based on “position qubits.” The technological difficulties of producing a useful scalable position-qubit quantum computer parallel the overwhelming difficulties in performing a double-slit interference experiment on an object comprising a million to a billion fermions. (shrink)

The universality assumption (“U”) that quantum wave states only evolve by linear or unitary dynamics has led to a variety of paradoxes in the foundations of physics. U is not directly supported by empirical evidence but is rather an inference from data obtained from microscopic systems. The inference of U conflicts with empirical observations of macroscopic systems, giving rise to the century-old measurement problem and subjecting the inference of U to a higher standard of proof, the burden of which lies (...) with its proponents. This burden remains unmet because the intentional choice by scientists to perform interference experiments that only probe the microscopic realm disqualifies the resulting data from supporting an inference that wave states always evolve linearly in the macroscopic realm. Further, the nature of the physical world creates an asymptotic size limit above which interference experiments, and verification of U in the realm in which it causes the measurement problem, seem impossible for all practical purposes if nevertheless possible in principle. This apparent natural limit serves as evidence against an inference of U, providing a further hurdle to the proponent’s currently unmet burden of proof. The measurement problem should never have arisen because the inference of U is entirely unfounded, logically and empirically. (shrink)

I accept that McTaggart's A-series and B-series are not inter-reducible and that both are needed for a complete temporal description of a physical system. I consider the Wigner's Friend thought experiment. The A-series are associated with each (quantum) system, and relativity is associated with the B-series. I consider temporal evolution through this 'hybrid' time. We may define the rate of temporal flow as 1 B-series second per A-series second.

This paper proposes an interpretation of time that is an 'A-theory' in that it incorporates both McTaggart's A-series and his B-series. The A-series characteristics are supposed to be 'ontologically private' analogous to qualia in the problem of other minds, such as in the Inverted Spectrum thought experiment, and is given a definition. The main idea is then that the experimenter and the cat do not share the same A-series characteristics, e.g. the same 'now', to some extent. So there is no (...) single time at which the cat gets ascribed different states, one by the experimenter and one by the cat. Also it is proposed one may define an ontologically private 'unit of becoming' that coordinatizes the future/present/past A-series spectrum as well as allow one to calculate rates of becoming with seconds. The latter are taken to measure differences in B-series times. (shrink)

A theory of time was proposed in "A theory of time", an early version of which is on PhilPapers. The idea was that the A-series features of a physical system are ontologically private, and this was given a mathematical definition. Also B-series features are ontologically public. This brief note is a detailed rumination on path-integrals and Schrodinger's Cat, in this theory.

The purpose of this yet-another version of this note is to make another attempt to show how an 'AB-series' interpretation of time, given in a companion paper, leads, surprisingly, apparently, to the signature of the physicists' important AdS^5 geometry. This is not a theory of 2 time dimensions. Rather, it is a theory of 1 time dimension that has both A-series and B-series characteristics.

The UNBELIEVABLE similar ideas between Theise and Menas’ ideas (2016) and my ideas (2002-2008) in Physics and Cognitive Neuroscience and Philosophy (the mind-brain problem, quantum mechanics, etc.) -/- (2016) Theise D. Neil (Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY, USA) and Kafatos C. Menas (bDepartment of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA; cSchmid College of Science & Technology, Chapman University, Orange, CA, USA) (2016), REVIEW - Fundamental awareness: A (...) framework for integrating science, philosophy and metaphysics, in COMMUNICATIVE & INTEGRATIVE BIOLOGY, 2016, VOL. 9, NO. 3, e1155010 (19 pages), http://dx.doi.org/10.1080/19420889.2016.1155010 -/- A friend of mine indicated me the strike similarities between Theise and Kafatos’ ideas in their book (Fundamental awareness: A framework for integrating science, philosophy and metaphysics) and my ideas in 2002-20008! I do not have access to this book, but I investigate the ideas that are in a review about this work. Let me introduce the abstract of that Review: -/- The ontologic framework of Fundamental Awareness proposed here assumes that non-dual Awareness is foundational to the universe, not arising from the interactions or structures of higher level phenomena. The framework allows comparison and integration of views from the three investigative domains concerned with understanding the nature of consciousness: science, philosophy, and metaphysics. In this framework, Awareness is the underlying reality, not reducible to anything else. Awareness and existence are the same. As such, the universe is non-material, self-organizing throughout, a holarchy of complementary, process driven, recursive interactions. The universe is both its own first observer and subject. Considering the world to be non-material and comprised, a priori, of Awareness is to privilege information over materiality, action over agency and to understand that qualia are not a “hard problem,” but the foundational elements of all existence. These views fully reflect main stream Western philosophical traditions, insights from culturally diverse contemplative and mystical traditions, and are in keeping with current scientific thinking, expressible mathematically. (shrink)

Four initial postulates are presented (with two more added later), which state that construction of the physical universe proceeds from a sequence of discrete steps or "projections" --- a process that yields a sequence of discrete levels (labeled 0, 1, 2, 3, 4). At or above level 2 the model yields a (3+1)-dimensional structure, which is interpreted as ordinary space and time. As a result, time does not exist below level 2 of the system, and thus the quantum of action, (...) h, which depends on time (since its unit is time•energy), also does not exist below level 2. This implies that the quantum of action is not fundamental, and thus e.g. that the physical universe cannot have originated from a quantum fluctuation. When the gravitational interaction for the model is developed, it is seen that the basic ingredient for gravity is already operating at level 1 of the system, which implies that gravity, too, is not fundamentally quantum mechanical (since, as stated, h only kicks in at level 2) --- perhaps obviating the need for a quantum theory of gravity. Further arguments along this line lead to the conclusion that quantum fluctuations cannot be a source of gravity, and thus cannot contribute to the cosmological constant --- thereby averting the cosmological constant problem. Along the way, the model also provides explanations for dark energy, the beginning and ending of inflation, quark confinement, and more. Although the model dethrones the quantum, it nevertheless elevates an idea in physics that was engendered by quantum mechanics: the necessary role of "observers" in constructing the world. (shrink)

In quantum mechanics, the wave function of a N-body system is a mathematical function defined in a 3N-dimensional configuration space. We argue that wave function realism implies particle ontology when assuming: (1) the wave function of a N-body system describes N physical entities; (2) each triple of the 3N coordinates of a point in configuration space that relates to one physical entity represents a point in ordinary three-dimensional space. Moreover, the motion of particles is random and discontinuous.

Based on an analysis of protective measurements, we show that the quantum state represents the physical state of a single quantum system. This result is more definite than the PBR theorem [Pusey, Barrett, and Rudolph, Nature Phys. 8, 475 (2012)].

We analyze the possible implications of spacetime discreteness for the special and general relativity and quantum theory. It is argued that the existence of a minimum size of spacetime may explain the invariance of the speed of light in special relativity and Einstein’s equivalence principle in general relativity. Moreover, the discreteness of spacetime may also result in the collapse of the wave function in quantum mechanics, which may provide a possible solution to the quantum measurement problem. These interesting results might (...) have some important implications for a complete theory of quantum gravity. (shrink)

We present a theory of discontinuous motion of particles in continuous space-time. We show that the simplest nonrelativistic evolution equation of such motion is just the Schroedinger equation in quantum mechanics. This strongly implies what quantum mechanics describes is discontinuous motion of particles. Considering the fact that space-time may be essentially discrete when considering gravity, we further present a theory of discontinuous motion of particles in discrete space-time. We show that its evolution will naturally result in the dynamical collapse process (...) of the wave function, and this collapse will bring about the appearance of continuous motion of objects in the macroscopic world. (shrink)

I show how omissions lead to robustness and can justify distortions, and I give inferentially relevant explications of abstraction and idealization. Abstraction is explicated as the omission of all and only those claims that use a specific vocabulary; idealization is explicated as the distortion of only those claims that use a specific vocabulary. With these explications, abstraction can justify idealization. As examples of how abstraction justifies idealization and leads to robustness, I discuss Beauchamp and Childress's four principles of biomedical ethics (...) and the qualitative treatment of the Schrödinger equation. (shrink)

in: Compendium of Quantum Physics, ed. by F. Weinert, K. Hentschel, D. Greenberger, and B. Falkenburg (Springer 2008).

We argue about a conceptual approach to quantum formalism. Starting from philosophical conjectures (Platonism, Idealism and Realism) as basic ontic elements (namely: math world, data world, and state of matter), we will analyze the quantum superposition principle. This analysis bring us to demonstrate that the basic assumptions affect in different ways:(a) the general problem of the information and computability about a system, (b) the nature of the math tool utilized and (c) the correspondent physical reality.

This paper shows how the classical finite probability theory (with equiprobable outcomes) can be reinterpreted and recast as the quantum probability calculus of a pedagogical or toy model of quantum mechanics over sets (QM/sets). There have been several previous attempts to develop a quantum-like model with the base field of ℂ replaced by ℤ₂. Since there are no inner products on vector spaces over finite fields, the problem is to define the Dirac brackets and the probability calculus. The previous attempts (...) all required the brackets to take values in ℤ₂. But the usual QM brackets <ψ|ϕ> give the "overlap" between states ψ and ϕ, so for subsets S,T⊆U, the natural definition is <S|T>=|S∩T| (taking values in the natural numbers). This allows QM/sets to be developed with a full probability calculus that turns out to be a non-commutative extension of classical Laplace-Boole finite probability theory. The pedagogical model is illustrated by giving simple treatments of the indeterminacy principle, the double-slit experiment, Bell's Theorem, and identical particles in QM/Sets. A more technical appendix explains the mathematics behind carrying some vector space structures between QM over ℂ and QM/Sets over ℤ₂. (shrink)

In this article I raise a new problem for quantum mechanics, which I call the control problem. Like the measurement problem, the control problem places a fundamental constraint on quantum theories. The characteristic feature of the problem is its focus on state preparation. In particular, whereas the measurement problem turns on a premise about the completeness of the quantum state ('no hidden variables'), the control problem turns on a premise about our ability to prepare or control quantum states. After raising (...) the problem, I discuss some applications. I suggest that it provides a useful new lens through which to view existing theories or interpretations, in part because it draws attention to aspects of those theories that the measurement problem does not. I suggest that it also helps clarify the physical significance of the well-known no-go result—the no-cloning theorem—on which it is based. (shrink)

The idea that mind and body are distinct entities that interact is often claimed to be incompatible with physics. The aim of this paper is to disprove this claim. To this end, we construct a broad mathematical framework that describes theories with mind–body interaction as an extension of current physical theories. We employ histories theory, i.e., a formulation of physical theories in which a physical system is described in terms of a set of propositions about possible evolutions of the system (...) and a probability assignment to such propositions. The notion of dynamics is incorporated into the probability rule. As this formulation emphasises logical and probabilistic concepts, it is ontologically neutral. It can be used to describe mental ‘degrees of freedom’ in addition to physical ones. This results into a mathematical framework for psycho-physical interaction. Interestingly, a class of ΨΦ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Psi \Phi$$\end{document}I theories turns out to be compatible with energy conservation. (shrink)

In ‘Reichenbach's cubical universe and the problem of the external world’, Elliott Sober attempts a refutation of solipsism à la Reichenbach. I here contrast Sober's line of argument with observati...

I respond to Vaidman’s recent criticisms of my paper “A New Problem for Quantum Mechanics”.

The paper offers an argument against an intuitive reading of the Stone-von Neumann theorem as a categoricity result, thereby pointing out that this theorem does not entail any model-theoretical difference between the theories that validate it and those that don't.

The paper investigates the type of realism that best suits the framework of decoherence taken at face value without postulating a plurality of worlds, or additional hidden variables, or non-unitary dynamical mechanisms. It is argued that this reading of decoherence leads to an extremely radical type of perspectival realism, especially when cosmological decoherence is considered.

Building on self-professed perspectival approaches to both scientific knowledge and causation, I explore the potentially radical suggestion that perspectivalism can be extended to account for a type of objectivity in science. Motivated by recent claims from quantum foundations that quantum mechanics must admit the possibility of observer-dependent facts, I develop the notion of ‘perspectival objectivity’, and suggest that an easier pill to swallow, philosophically speaking, than observer-dependency is perspective-dependency, allowing for a notion of observer-independence indexed to an agent perspective. Working (...) through the case studies of colour perception and causal perspectivalism, I identify two places within which I claim perspectival objectivity is already employed, and make the connection to quantum mechanics through Bohr’s philosophy of quantum theory. I contend that perspectival objectivity can ensure, despite the possibility of perspective-dependent scientific facts, the objectivity of scientific inquiry. (shrink)

Quantum mechanics involves a generalized form of information, that of quantum information. It is the transfinite generalization of information and re-presentable by transfinite ordinals. The physical world being in the current of time shares the quality of “choice”. Thus quantum information can be seen as the universal substance of the world serving to describe uniformly future, past, and thus the present as the frontier of time. Future is represented as a coherent whole, present as a choice among infinitely many alternatives, (...) and past as a well-ordering obtained as a result of a series of choices. The concept of quantum information describes the frontier of time, that “now”, which transforms future into past. Quantum information generalizes information from finite to infinite series or collections. The concept of quantum information allows of any physical entity to be interpreted as some nonzero quantity of quantum information. The fundament of quantum information is the concept of ‘quantum bit’, “qubit”. A qubit is a choice among an infinite set of alternatives. It generalizes the unit of classical information, a bit, which refer to a finite set of alternatives. The qubit is also isomorphic to a ball in Euclidean space, in which two points are chosen. (shrink)

Introduction The EDWs perspective, a new general framework of thinking for all physicists! “The present situation in physics is as if we know chess, but we don't know one or two rules.” Richard Feynman In other works (2002, 2005, 2008, 2011, 2012, 2014, 2015, 2016; Vacariu and Vacariu 2010, 2016a, 2016b), we have showed that the greatest illusion of human knowledge is the notion of “world”, of “uni-verse”, or as we called it, the “Unicorn-world”, and this notion has survived from (...) the oldest times until today. In these works, we have indicated that the “world”, the “Universe” does not exist, but the “Epistemologically Different Worlds” (EDWs) exist (more specifically, for many EDWs, it is about the entities and the interactions which really exist and only represent these EDWs). We emphasize that the EDWs perspective is a new Copernican revolution in human thinking, the greatest movement in Physics, Cognitive Neuroscience, and Philosophy! During the past 15 years, we have applied the EDW paradigm to the main particular sciences and main theories in physics (quantum mechanics, Einstein’s special and general relativity, and the relationship between them), cognitive science (to the main theories like computationalism, connectionism, and the dynamical system approach), cognitive neuroscience, and biology (just to the relationship between life and organism/cell). Also, we showed that the entire Philosophy since Ancient period until now is totally wrong (just because, all philosophical approaches have been constructed within the “Unicorn-world”). This book closes the circle of great topics concerning the main particular sciences (physics, cognitive (neuro)science, and biology) and philosophy grasped in all our previous books (2008-2016): it is about the relationship between the main theories and concepts of Physics vs. the EDWs perspective! The main theories that we investigate in this and our previous works have been created within the Unicorn-world, therefore, all these approaches have been quite wrong. Some of these theories have been partially re-write in our previous books (Einstein both relativities, thermodynamics, and our EDWs perspective, see Vacariu and Vacariu 2016, 2017, etc.), but even some notions of these theories were wrong. For instance, in our previous book (2016), we indicated that “spacetime” cannot even exist (spacetime cannot have any kind of ontology!). Therefore, in 2017, re-wrote Einstein’s both relativities without “spacetime”. The majority of theories in Physics have been created within the unicorn world and therefore these theories have been quite wrong or at least the authors of these scientific theories have been used wrong concepts. This book is a collections of our previous ideas, but we strongly emphasize that some of these idea are quite developed in this work. Therefore, this book can be labeled as: “a philosopher overwriting Physics within a new paradigm, the ‘Epistemologically Different World’ (EDWs) perspective”! We emphasize that some parts of this book are from our previous works (but even so, these parts are modified, we added new paragraphs or sub-chapters), but some parts are new written. In general, the new details of this book are the results of following Presura’s book about Physics (2014) written in Romanian. His book is a general overview of the main theories in Physics. Presura is a physicist who wrote a book about these theories in a quite easy language for large public (also for philosophers). There are quite many paragraphs from Presura’s book that are quoted in our book. We emphasize that Presura’s paragraphs inserted in our book are our translations. Also, we inserted quite many of his ideas but we mentioned his name each time. We apologize if some notions or ideas are wrong translated. The first Chapter is about the EDWs perspective. In Chapter 2, we introduce more details about the rejection of “spacetime”. In Chapter 3, we insert the ideas from our book Vacariu and Vacariu 2017 about Einstein’s relativity without “spacetime”. However, new paragraphs are introduced in this chapter. In Chapter 4, we are indicating that all alternatives of quantum mechanics have been wrong: parts of this chapter are from our previous works, other parts and paragraphs are new ideas/comments. In Chapter 5, we discuss about the Grand Unified Theory (GUT) and the Theory of Everything (TOE), Big Bang (transformed, according to the EDWs perspective, in many Big Bangs – in this way, we avoid Alan Guth’s empty notion of “inflation” which contradict Einstein’s principle of constant speed of light which cannot be surpassed by anything else). In Chapter 6, we introduce an updated version about the dark matter and the dark energy (in 2016, we published a book about “dark matter/energy, space and time and other pseudo-notions in Cosmology” and in 2020 we published a chapter in a book edited by the physicist Michael Smith - see the bibliography. We mention that, in that book, except our chapter, all the other chapters are written by physicists!). For instance, in section 6.4, we introduce a new alternative to dark energy and dark matter, an alternative that is different even from this updated approach! In Chapter 7, we furnish more details about the non-existence of “hyperspace” and the futility of the “superstring theory”. In Chapter 8 in indicate the clear great distinction between our EDWs and Primas and Atmanspascher’s approach (under Spinoza’s “dual aspects” approach and Bohr’s “complementarity” constructed within the unicorn world). In the last chapter, chapter 9, we analysis Rovelli’s rejection of “spacetime” (based on Einstein’s general relativity) within the unicorn world. We rejected the ontology of “spacetime”, but our argument is totally different than Rovelli’s argument. Moreover, we indicate that Rovelli’s argument is quite wrong, constructed within the unicorn world. As a conclusion, we emphasize that we have overwritten the main theories, ideas and concepts of Physics within the new Copernican framework of thinking, the EDWs perspective. The umbrella under which we have been working indicates that the great problems of Physics are pseudo-problems constructed within the wrong framework, the “Unicorn world” (the Universe/world) which does not really exist. Therefore, we have to replace the unicorn world with the EDWs! At the end of our Introduction, we mention that that have been many physicists, cognitive neuroscientists and philosophers who have published UNBELIEVABLE similar ideas to our ideas long time after our ideas being published!).[ Discovering the EDWs, Gabriel Vacariu HAS CHANGED EVERYTHING in human knowledge! His EDWs is the greatest CHALLENGE in the history of human thinking. Many people have published UNBELIEVABLE similar ideas to our ideas long time after we published and posted our first works on Internet. About the UNBELIEVABLE SIMILARITIES here: academia researchgate philpapers All our main ideas (the mind-brain problem, main problems of cognitive science and quantum mechanics, Einstein’s relativity vs. quantum mechanics, etc.) from my Springer’s book (2016) can be found in my PhD thesis (2007), UNSW (Sydney, Australia, posted on university’s website, free, by the university’s team in 2007) unsworks.unsw.... Nobody discovered the EDWs during 2500 years, Gabriel Vacariu discovered them in 2002 (first publication), 2003 and 2005. Amazing, in the last years, many people also “discovered” the existence of EDWs! Statistically, it is quite impossible, so many people (hundreds!) to “discover” the EDWs! (Don’t forget, we have been working within the Internet’s world, therefore, communication is much faster than 20 years ago...) “I don't care that they stole my idea. I care that they don't have any of their own… The present is theirs; the future, for which I really worked, is mine.” (Nikolai Tesla) What these authors have been missing comparing with Gabriel Vacariu? They have been either physicists or cognitive neuroscientists or philosophers while Gabriel Vacariu is a philosopher working Cognitive Neuroscience and Physics! This is the main reason they have been unable to discover the EDWs and to think and write the “Metaphysics of EDWs” (our book 2019)!] It is not something surprising since the EDWs has changed everything in human knowledge! Therefore, we end this chapter with this paragraph: “The distance between the pioneers and the much smaller followers becomes so great that the latter cannot reach the former; the age of servile imitation begins – yet not of nature, but of the style of the great masters, zealous copyists remove the labels from the elixirs of the Magi and put them on their vials.” (Arnold Gehlen, Images of time). (shrink)

This invited article is a response to the paper “Quantum Misuse in Psychic Literature,” by Jack A. Mroczkowski and Alexis P. Malozemoff, published in this issue of the Journal of Near-Death Studies. Whereas I sympathize with Mroczkowski’s and Malozemoff’s cause and goals, and I recognize the problem they attempted to tackle, I argue that their criticisms often overshot the mark and end up adding to the confusion. I address nine specific technical points that Mroczkowski and Malozemoff accused popular writers in (...) the fields of health care and parapsychology of misunderstanding and misrepresenting. I argue that, by and large—and contrary to Mroczkowski’s and Malozemoff’s claims—the statements made by these writers are often reasonable and generally consistent with the current state of play in foundations of quantum mechanics. (shrink)

Previzualizare carte -/- O introducere la nivel fenomenologic, cu un aparat matematic minimal, în mecanica cuantică. Un ghid pentru cine dorește să înțeleagă cea mai modernă, mai complexă și mai neconformă disciplină fizică, un domeniu care a schimbat fundamental percepțiile oamenilor de știință despre Lume. În 1900, Max Planck a introdus ideea că energia este cuantificată, pentru a obţine o formulă la energia emisă de un corp negru. În 1905, Einstein a explicat efectul fotoelectric postulând că energia luminii vine în (...) cuante numite fotoni. In 1913, Bohr a explicat liniile spectrale ale atomului de hidrogen, din nou prin utilizarea de cuante. În 1924, Louis de Broglie a prezentat teoria sa a undelor de materie. Aceste teorii, deşi de succes, au fost strict fenomenologice: nu a existat nicio justificare riguroasă pentru cuantificare. Ele sunt denumite colectiv ca vechea teorie cuantică. Expresia "fizica cuantica" a fost folosită pentru prima dată în lucrarea lui Johnston: Universul lui Planck în lumina fizicii moderne. Mecanica cuantică modernă s-a născut în 1925, când Heisenberg a dezvoltat mecanica matriceală şi Schrödinger a inventat mecanica ondulatorie şi ecuaţia Schrödinger. Schrödinger a demonstrat ulterior că cele două abordări au fost echivalente. Heisenberg a formulat principiul său de incertitudine în 1927, iar interpretarea de la Copenhaga a apărut în aproximativ acelaşi timp. În 1927, Paul Dirac a unificat mecanica cuantică cu teoria relativităţii restrânse. De asemenea, el a utilizat printre primii teoria operatorilor, inclusiv notaţia influenţială bra-ket. În 1932, John von Neumann a formulat baza matematică riguroasă pentru mecanica cuantică, ca teoria operatorilor. În anii 1940, electrodinamica cuantică a fost dezvoltată de Feynman, Dyson, Schwinger, şi Tomonaga. Ea a servit ca model pentru teoriile ulterioare ale câmpului cuantic. Interpretarea multiplelor lumi a fost formulat de către Everett în 1956. Cromodinamica cuantică a avut o istorie lungă, de la începutul anilor 1960. Teoria aşa cum o ştim astăzi a fost formulată de către Polizter, Gross şi Wilzcek în 1975. Bazându-se pe munca de pionierat a lui Schwinger, Higgs, Goldstone şi alţii, Glashow, Weinberg şi Salam au demonstrat în mod independent cum că forţa nucleară slabă şi electrodinamica cuantică ar putea fi unite într-o singură forţă electroslabă. Încă de la începuturile sale, cele mai multe rezultate contra-intuitive ale mecanicii cuantice au provocat puternice dezbateri filozofice şi mai multe interpretări. Interpretarea de la Copenhaga, datorată în mare parte lui Niels Bohr, a fost interpretarea standard a mecanicii cuantice, atunci când a fost formulată pentru prima dată. În conformitate cu aceasta, natura probabilistică a predicţiilor mecanicii cuantice nu poate fi explicată în termeni ai altor teorii deterministe, şi nu reflectă pur şi simplu cunoştinţele noastre limitate. Mecanica cuantică oferă rezultate probabilistice deoarece universul fizic este în sine probabilistic, mai degrabă decât determinist. O mare parte a tehnologiei moderne funcţionează în conformitate cu principiile din mecanica cuantică. Exemplele includ laserul, microscopul electronic, şi imagistica prin rezonanţă magnetică. Cele mai multe dintre calculele efectuate în chimia computaţională se bazează pe mecanica cuantică. -/- CUPRINS -/- 1 Mecanica cuantică - - - Descrierea teoriei - - - Istorie - - - Formulări matematice - - - Interacția cu alte teorii ale fizicii - - - - - - Mecanica cuantică și fizica clasică - - - - - - Interpretarea de la Copenhaga a cinematicii cuantice versus clasice - - - - - - Relativitatea generală și mecanica cuantică - - - - - - Încercări pentru o teorie a câmpului unificată - - - Formulări matematice echivalente - - - Implicații filosofice - - - 1.1 Atomul și cuanta - - - 1.2 Radiația corpului negru și cuantificarea lui Planck - - - - - - Radiația corpului negru - - - - - - Cuantificarea și constanta lui Planck - - - - - - - - - Metode de cuantificare - - - - - - - - - - - - Cuantificarea canonică - - - - - - - - - Constanta lui Planck - - - - - - - - - - - - Valoare - - - - - - - - - - - - Semnificația valorii - - - 1.3 Cuanta de lumină (Fotoni) - - - - - - Proprietăți fizice - - - - - - Optica cuantică - - - 1.4 Efectul fotoelectric - - - - - - Mecanismul de emisie - - - - - - Observații experimentale ale emisiei fotoelectrice - - - - - - Descrierea matematică - - - - - - Utilizări și efecte - - - - - - - - - Fotomultiplicatori - - - - - - - - - Senzori de imagine - - - - - - - - - - - - Electroscop cu frunză de aur - - - - - - - - - Spectroscopie fotoelectronică - - - - - - - - - Nave spațiale - - - - - - - - - Praful lunar - - - - - - - - - Dispozitive de vedere pe timp de noapte - - - 1.5 Unde materiale - Relațiile de Broglie - - - - - - Context istoric - - - - - - Ipoteza de Broglie - - - - - - Relațiile de Broglie - - - - - - Interpretări - - - 1.6 Modelul Bohr al atomului - - - - - - Origine - - - 1.7 Nivele energetice cuantificate: Undele electronilor - - - - - - Explicație - - - - - - Tranziții ale nivelelor de energie - - - 1.8 Difracția electronilor - - - - - - Proprietăți cuantice - - - - - - Difracția electronilor - - - - - - Interacțiunea electronilor cu materia - - - - - - Microscop cu electroni de transmisie 2 Dualitatea undă-particulă - - - Tratamentul în mecanica cuantică modernă - - - Vizualizare - - - Aplicarea la modelul Bohr - - - 2.1 Complementaritatea - - - - - - Conceptul - - - - - - Natura - - - - - - Considerații suplimentare - - - - - - Experimente - - - 2.2 Microscopul lui Heisenberg - - - - - - Argumentul lui Heisenberg - - - - - - Analiza argumentului - - - 2.3 Experimentul celor două fante - - - - - - Prezentare generală - - - - - - Interpretările experimentului - - - - - - - - - Interpretarea de la Copenhaga - - - - - - - - - Formularea integrală a căii - - - - - - - - - Interpretarea relațională - - - - - - - - - Interpretarea multiplelor-lumi - - - 2.4 Disputa Einstein-Bohr - - - - - - Dezbateri pre-revoluționare - - - - - - Revoluția cuantică - - - - - - Post-revoluția: prima etapă - - - - - - - - - Argumentul lui Einstein - - - - - - - - - Răspunsul lui Bohr - - - - - - - - - A doua critică a lui Einstein - - - - - - - - - Triumful lui Bohr - - - - - - Post-revoluție: a doua etapă - - - - - - Post-revoluție: a treia etapă - - - - - - - - - Argumentul EPR - - - - - - - - - Răspunsul lui Bohr - - - - - - Post-revoluție: etapa a patra - - - 2.5 Experimentul alegerii întârziate - - - - - - Introducere - - - - - - Versiunea fantei duble - - - - - - Detalii experimentale - - - - - - Fantele duble în laborator și în cosmos - - - - - - Concluzii 3 Ecuația Schrödinger - - - Ecuația dependentă de timp - - - Ecuația independentă de timp - - - Interpretarea funcției de undă - - - Ecuația de undă pentru particule - - - 3.1 Stări cuantice - - - - - - Descrierea conceptuală - - - - - - - - - Stări pure - - - - - - - - - Imaginea lui Schrödinger vs. imaginea lui Heisenberg - - - - - - În fizica matematică - - - - - - - - - Valori proprii și vectori proprii - - - 3.2 Funcția de undă - - - - - - Exemple non-relativiste - - - - - - - - - Barieră potențială finită - - - - - - - - - Atomul de hidrogen - - - 3.3 Colapsul funcției de undă - - - - - - Descrierea matematică - - - - - - - - - Procesul - - - - - - - - - Determinarea bazei preferate - - - - - - - - - Decoerența cuantică - - - - - - Istorie și context - - - 3.4 Interpretarea probabilităților (Problema măsurătorilor) - - - - - - Pisica lui Schrödinger - - - - - - Interpretări - - - 3.5 Formularea spațiului de fază - - - - - - Distribuția spațiului de fază - - - - - - Evoluția timpului - - - - - - Exemple - - - - - - - - - Potențial Morse - - - - - - - - - Tunelarea cuantică - - - - - - - - - Potențialul quartic - - - - - - - - - Starea pisicii lui Schrödinger 4 Pachete de unde - - - Unde și particule în mișcare - - - 4.1 Principiul incertitudinii - - - - - - Definire - - - - - - Utilizare - - - - - - Relația de incertitudine timp-energie - - - 4.1.1 Paradoxurile lui Zenon în mecanica cuantică - - - - - - Ahile și broasca țestoasă - - - - - - Paradoxul dihotomiei - - - - - - Paradoxul săgeții - - - - - - Soluții cuantice propuse - - - - - - - - - Peter Lynds - - - - - - - - - Hermann Weyl - - - - - - Efectul cuantic Zenon - - - 4.2 Funcții proprii - - - - - - Exemplul de derivată - - - 4.3 Operatorul impuls - - - - - - Definiție (spațiu de poziție) - - - - - - Proprietăți - - - - - - - - - Hermiticitatea - - - - - - - - - Relația canonică de comutație - - - - - - - - - Transformarea Fourier - - - 4.4 Forma generală a ecuației Schrodinger: Operatorul hamiltonian - - - - - - Ecuația Schrödinger - - - - - - Formalismul Dirac - - - 4.5 Postulatele mecanicii cuantice și semnificația măsurătorilor - - - - - - Postulate ale mecanicii cuantice - - - - - - - - - Postulatul 1: Definirea stării cuantice - - - - - - - - - Postulatul 2: Principiul corespondenței - - - - - - - - - Postulatul 3: Măsurarea - valori posibile ale unei observabile - - - - - - - - - Postulatul 4: Postulatul lui Born - interpretarea probabilistică a funcției de undă - - - - - - - - - Postulatul 5: Măsurarea - reducerea pachetului de unde; obținerea unei singure valori; proiecția stării cuantice - - - - - - - - - Postulatul 6: Evoluția temporală a stării cuantice - - - - - - Problema măsurării - - - - - - - - - Interpretarea stării relative 5 Soluții ale ecuației Schrödinger - - - 5.1 Particulă într-o cutie unidimensională - - - - - - Soluția unidimensională - - - - - - - - - Funcția de undă a poziției - - - - - - - - - - - - Funcția de undă a impulsului - - - - - - - - - Niveluri energetice - - - 5.2 Barieră rectangulară de potențial - - - - - - Calcul - - - - - - Transmisie și reflexie - - - - - - - - - E < V0 - - - - - - - - - E > V0 - - - - - - - - - E = V0 - - - - - - Observații și aplicații - - - 5.3 Puț de potențial finit - - - - - - Particulă într-o cutie 1-dimensională - - - 5.4 Paritatea - - - - - - Relații simple de simetrie - - - - - - Efectul inversiunii spațiale asupra unor variabile ale fizicii clasice - - - - - - - - - Par - - - - - - - - - Impar - - - - - - Posibile valori proprii în mecanica cuantică - - - 5.5 Oscilatorul armonic unidimensional - - - - - - Oscilator armonic unidimensional - - - - - - - - - Hamiltonianul și stările proprii ale energiei - - - - - - - - - Scale naturale pentru lungimi și energie - - - - - - - - - Stări foarte excitate - - - - - - - - - Soluții pentru spațiul de fază - - - 5.6 Operatorul momentului unghiular - - - - - - Momentul unghiular orbital - - - - - - Momentul unghiular de spin - - - - - - Momentul unghiular total - - - - - - Interpretare vizuală - - - - - - Relația de incertitudine dintre momentul unghiular și unghiul de rotație - - - 5.7 Particule identice - - - - - - Distingerea între particule - - - - - - Stările simetrice și antisimetrice - - - - - - Simetria de schimb - - - - - - Fermioni și bosoni - - - 5.8 Potențialul central (Potențialul cuantic) - - - - - - Potențialul cuantic ca parte a ecuației lui Schrödinger - - - - - - - - - Ecuația de continuitate - - - - - - - - - Ecuația cuantică Hamilton-Jacobi - - - - - - Proprietăți - - - - - - - - - Relația cu procesul de măsurare - - - - - - - - - Potențialul cuantic al unui sistem de n-particule - - - - - - Interpretarea și denumirea potențialului cuantic - - - - - - Aplicații - - - 5.9 Puțul de potențial - - - - - - Confinarea cuantică - - - - - - - - - În mecanica cuantică - - - - - - - - - În mecanica clasică 6 Paradoxuri și interpretări ale mecanicii cuantice - - - 6.1 Inseparabilitatea cuantică - - - - - - Inseparabilitatea cuantică - - - - - - Istorie - - - - - - Conceptul - - - - - - - - - Sensul inseparabilității - - - - - - - - - Paradoxul - - - - - - - - - Teoria variabilelor ascunse - - - - - - - - - Încălcarea inegalității Bell - - - - - - - - - Alte tipuri de experimente - - - - - - - - - Misterul timpului - - - - - - - - - Sursa pentru săgeata timpului - - - 6.2 Paradoxurile mecanicii cuantice - - - 6.3 Paradoxul EPR - - - - - - Istoria evoluțiilor EPR - - - - - - Mecanica cuantică și interpretarea ei - - - - - - Opoziția lui Einstein - - - - - - Descrierea paradoxului - - - - - - - - - Articolul EPR - - - 6.4 Interpretarea Copenhaga - - - - - - Fundal - - - - - - Principii - - - - - - Regula Born - - - - - - Natura colapsului - - - - - - Non-separabilitatea funcției de undă - - - - - - Dilema undă-particulă - - - - - - Acceptarea printre fizicieni - - - 6.5 Variabile ascunse - - - - - - Motivație - - - - - - "Dumnezeu nu joacă zaruri" - - - - - - Tentative timpurii - - - - - - Declarația de completitudine a mecanicii cuantice și dezbaterile Bohr-Einstein - - - - - - Paradoxul EPR - - - - - - Teorema lui Bell - - - - - - Teoria variabilelor ascunse a lui Bohm - - - - - - Evoluțiile recente - - - 6.6 Paradoxul pisicii lui Schrödinger - - - - - - Origine și motivație - - - - - - Experimentul de gândire - - - - - - Interpretarea de la Copenhaga - - - - - - Aplicații și teste - - - - - - Extensii - - - 6.7 Interpretarea ansamblului (statistică) - - - - - - Înțelesul lui "ansamblu" și "sistem" - - - - - - Pisica lui Schrödinger - - - 6.8 Interpretarea multiplelor lumi - - - - - - Origine - - - - - - Dezvoltare - - - - - - Interpretarea colapsului funcției de undă - - - - - - Interpretarea nereală/reală - - - - - - Descrierea MWI 7 Stările cuantice conform lui Dirac - - - Definiție - - - Vectorii de stare - - - Operatori - - - - - - Operatorul hamiltonian - - - - - - Matricea densității - - - Ecuațiile timp-evoluție în imaginea interacțiunilor - - - - - - Evoluția în timp a stărilor - - - - - - Evoluția în timp a operatorilor - - - - - - Evoluția în timp a matricei de densitate - - - Valori așteptate - - - Utilizarea imaginii interacțiunilor - - - 7.1 Ecuația de undă Dirac - - - - - - Formularea matematică - - - - - - Interpretarea fizică - - - - - - - - - Identificarea observabilelor - - - - - - - - - Teoria găurilor - - - 7.2 Notația bra-ket în mecanica cuantică - - - - - - Introducere - - - - - - Utilizarea în mecanica cuantică 8 Corespondența cu mecanica clasică - - - Ecuații de câmp - - - Ecuații de undă - - - Teoria cuantică - - - 8.1 Ecuația de mișare a lui Heisenberg (Reprezentările Heisenberg, Schrödinger și Dirac) - - - - - - Reprezentarea Heisenberg - - - - - - Reprezentarea Schrödinger - - - - - - Reprezentarea de interacțiune (Dirac) - - - - - - Comparație a evoluției în toate imaginile/reprezentările - - - 8.2 Teorema Ehrenfest și limita clasică a mecanicii cuantice - - - 8.3 Principiul corespondenței - - - - - - Mecanica cuantică - - - 8.4 Aproximarea WKB - - - - - - Scurt istoric - - - - - - Metoda WKB - - - - - - Aplicarea la ecuația Schrödinger - - - - - - - - - Aproximarea departe de punctele de cotitură - - - - - - - - - Comportamentul în apropierea punctelor de cotitură - - - - - - - - - Condițiile de potrivire - - - - - - - - - Densitatea de probabilitate - - - 8.5 Teorema adiabatică - - - - - - Procesele diabatice vs. adiabatice - - - - - - Exemple de sisteme - - - - - - - - - Pendulul simplu - - - - - - - - - Oscilator armonic cuantic 9 Momentul unghiular și spinul - - - 9.1 Momentul unghiular - - - - - - Moment ungiular de spin, orbital, și total - - - - - - Cuantizarea - - - - - - Incertitudinea - - - - - - Momentul unghiular total ca generator de rotații - - - 9.2 Spin și matrice - - - - - - Numărul cuantic - - - - - - Fermioni și bozoni - - - - - - Teorema statisticii spinului - - - - - - Paritate - - - 9.3 Mecanica matriceală - - - - - - Epifanie la Helgoland - - - - - - Cele trei documente fundamentale - - - - - - Raționamentul lui Heisenberg - - - - - - Bazele mecanicii matriceale - - - 9.3.1 Particule cu spin în câmp magnetic: Rezonanța magnetică nucleară - - - - - - Teoria rezonanței magnetice nucleare - - - - - - - - - Spin nuclear și magneți - - - - - - - - - Valorile momentului unghiular de spin - - - - - - - - - Energia de spin într-un câmp magnetic - - - 9.3.2 Precesia spinului în câmp magnetic (Rezonanța paramagnetică a electronilor) - - - - - - Rezonanță paramagnetică a electronilor - - - - - - - - - Originea unui semnal EPR - - - 9.4 Cuplarea momentelor unghiulare - - - - - - Conservarea momentului unghiular - - - - - - Cuplarea spin-orbită - - - - - - - - - Cuplarea LS - - - - - - - - - Cuplarea jj - - - 9.5 Principiul de excluziune Pauli - - - - - - Prezentare generală - - - - - - Principiul Pauli în teoria cuantică avansată - - - - - - Atomii și principiul Pauli - - - 9.6 Starea singlet și paradoxul EPR - - - - - - Istorie - - - - - - Exemple - - - - - - Reprezentări matematice - - - - - - Singleți și stări inseparate - - - 9.7 Teorema Bell - - - - - - Fundal istoric - - - - - - Prezentare generală - - - - - - Importanța - - - - - - Realismul local - - - 9.8 Inegalitatea Bell - - - - - - Testarea prin experimente practice - - - - - - Două clase de inegalități Bell - - - - - - Provocări practice - - - - - - Aspecte metafizice - - - - - - Remarci generale 10 Materia cuantică - - - 10.1 Atomul de hidrogen - - - - - - Izotopi - - - - - - Ionul de hidrogen - - - - - - Descrierea clasică a eșuat - - - - - - Modelul Bohr-Sommerfeld - - - 10.2 Atomul de hidrogen în interpretarea de la Copenhaga - - - - - - Soluțiile ecuației lui Schrödinger - - - 10.3 Structura fină a hidrogenului - - - - - - Structura brută - - - - - - Corecții relativiste - - - - - - Atomul de hidrogen - - - - - - - - - Corecția relativistă pentru energia cinetică - - - 10.4 Interacția spin-orbită - - - - - - Energia unui moment magnetic - - - - - - - - - În solide - - - - - - Câmp electromagnetic oscilant - - - 10.5 Explicația cuantică a tabelului periodic al elementelor - - - - - - Grupe - - - - - - Blocuri - - - - - - Configurație electronică - - - - - - Învelișuri electronice - - - - - - - - - Razele atomice - - - - - - A doua versiune și dezvoltarea ulterioară - - - - - - Tabele cu structuri diferite - - - - - - - - - ADOMAH (2006) - - - - - - - - - Modelul tridimensional al fizicianului Timothy Stowe - - - 10.6 Structura moleculelor - - - - - - Istorie - - - - - - Structura electronilor - - - - - - - - - Modelul ondulatoriu - - - - - - - - - Legături de valență - - - - - - - - - Orbitale moleculare - - - - - - - - - Teoria funcțională a densității - - - - - - Dinamica chimică - - - - - - - - - Dinamica chimică adiabatică - - - - - - - - - Dinamica chimică non-adiabatică - - - 10.7 Condensat Bose-Einstein și condensat fermionic - - - - - - Condensat Bose-Einstein - - - - - - - - - Istorie - - - - - - - - - Cercetări curente - - - - - - Condensat fermionic - - - - - - - - - Superfluiditate - - - - - - - - - Superfluide fermionice - - - - - - - - - Crearea primelor condensate fermionice - - - 10.8 Gazul Fermi și gazul Bose - - - - - - Gazul Fermi - - - - - - - - - Descriere - - - - - - Gazul Bose - - - - - - - - - Introducere și exemple 11 Perturbații - - - Hamiltonieni aproximați - - - Aplicarea teoriei perturbației - - - - - - Limitări - - - - - - - - - Perturbații mari - - - - - - - - - Stările non-adiabatice - - - - - - - - - Computerizarea dificultăților - - - Teoria perturbației independente de timp - - - - - - Corecții de ordinul întâi - - - - - - Efectele degenerării - - - 11.1 Metode de aproximare pentru stări staționare - - - - - - Proprietăți ale stării staționare - - - 11.2 Efectul Stark - - - - - - Istorie - - - - - - Mecanism - - - - - - Teoria perturbării - - - - - - Efect stark limitat cuantic - - - 11.3 Teoria perturbației dependente de timp - - - - - - Metoda variației constantelor - - - - - - Teoria perturbației puternice - - - 11.4 Perturbația periodică: Regula de aur a lui Fermi - - - - - - Rata și derivarea acesteia - - - - - - - - - Derivarea în teoria perturbării dependente de timp - - - 11.5 Teoria dispersiei. Aproximarea Born - - - - - - Fundamente conceptuale - - - - - - - - - Ținte compuse și ecuații de interval - - - - - - În fizica teoretică - - - - - - Dispersia în mecanica cuantică a fotonului și a nucleelor - - - - - - Aproximarea Born - - - - - - - - - Aplicații - - - 11.6 Amplitudinea de împrăștiere - - - - - - Expansiunea undelor parțiale 12 Teoria cuantică a câmpului - - - Varietăți de abordări - - - - - - Abordări perturbative și non-perturbative - - - - - - TCC și gravitația - - - Definiție - - - - - - Dinamica - - - - - - Stări - - - - - - Câmpuri și radiații - - - Principii - - - - - - Câmpuri clasice și cuantice - - - 12.1 Electrodinamica cuantică - - - - - - Viziunea lui Feynman asupra electrodinamicii cuantice - - - - - - - - - Introducere - - - - - - Construcții de bază - - - - - - - - - Amplitudini de probabilitate - - - - - - - - - Propagatori - - - - - - - - - Renormalizarea în masă - - - - - - - - - Concluzii - - - 12.2 Efectul Zeeman - - - - - - Nomenclatură - - - - - - Prezentare teoretică - - - - - - Aplicații - - - - - - - - - Astrofizică - - - - - - - - - Răcirea laserului - - - - - - - - - Energia Zeeman mediată de cuplare a spinului și mișcări orbitale - - - 12.3 Efectul Aharonov-Bohm - - - - - - Semnificație - - - - - - Potențiale vs. câmpuri - - - - - - Acțiune globală vs. forțe locale - - - - - - Localitatea efectelor electromagnetice - - - 12.4 Cuantizarea fluxului magnetic - - - 12.5 Filosofia macrorealismului și SQUID - - - - - - Inegalitatea Leggett–Garg - - - - - - - - - Încălcări experimentale - - - - - - SQUID 13 Modelul standard - - - Particule elementare - - - - - - Fermioni - - - - - - - - - Cuarci - - - - - - - - - Leptoni - - - - - - Bosoni - - - - - - Particule ipotetice - - - Particule compuse - - - - - - Hadroni - - - - - - Barioni - - - - - - Mezoni - - - - - - Nuclee atomice - - - - - - Atomi - - - - - - Molecule - - - Substanțe condensate - - - Alte particule - - - Clasificare după viteză - - - 13.1 Extensii ale Modelului Standard - - - - - - Marea unificare - - - - - - Supersimetria - - - - - - Teoria corzilor - - - - - - Teoria preonilor - - - 13.2 Cromodinamica cuantică - - - - - - Teorie - - - - - - - - - Unele definiții - - - - - - - - - Observații suplimentare: dualitatea - - - - - - - - - Grupuri de simetrie - - - - - - - - - Lagrangieni - - - - - - - - - Câmpuri - - - - - - - - - - - - Dinamica - - - - - - - - - - - - Confinarea și legea zonală 14 Gravitația cuantică - - - Prezentare generală - - - Mecanica cuantică și relativitatea generală - - - - - - Graviton - - - - - - Dilaton - - - - - - Nonrenormalizabilitatea gravitației - - - - - - Gravitația cuantică ca o teorie eficientă a câmpului - - - - - - Dependența spațiu-timpului de fundal - - - - - - Teoria corzilor - - - - - - - - - Teorii independente de fundal - - - - - - Gravitația cuantică semi-clasică - - - - - - Problema timpului - - - Teorii candidate - - - - - - Teoria corzilor - - - - - - Gravitația cuantică în bucle - - - - - - Alte abordări - - - Teste experimentale - - - 14.1 Gravitația cuantică în bucle - - - - - - Istorie - - - - - - Covarianța generală și independență de fundal - - - - - - Limita semiclasică - - - - - - - - - Ce este limita semiclastică? - - - - - - - - - De ce GCB nu ar avea relativitatea generală ca limită semiclasică? - - - - - - - - - Dificultăți la verificarea limitei semiclasice a GCB - - - - - - - - - Progresul în demonstrarea GCB are limita semiclastică corectă - - - - - - Aplicații fizice ale GCB - - - - - - - - - Entropia găurii negre - - - - - - - - - Radiația Hawking în GCB - - - - - - - - - Stea Planck - - - - - - - - - Cosmologică cuantică în bucle - - - - - - - - - Fenomenologia GCB - - - - - - - - - Amplitudini de împrăștiere independente de fundal - - - - - - Gravitoni, teoria corzilor, supersimetrie, dimensiuni suplimentare în GCB - - - - - - GCB și programele de cercetare aferente - - - - - - Probleme și comparații cu abordări alternative - - - 14.2 Teoria corzilor - - - - - - Fundamente - - - - - - - - - Corzi - - - - - - - - - Dimensiuni suplimentare - - - - - - - - - Dualitatile - - - - - - - - - Brane - - - - - - Teoria-M - - - - - - - - - Unificarea teoriilor supercorzilor - - - - - - - - - Teoria matriceală - - - - - - Găuri negre - - - - - - - - - Formula Bekenstein-Hawking - - - - - - - - - Derivarea în cadrul teoriei corzilor - - - - - - Corespondența AdS/CFT - - - - - - - - - Prezentare generală a corespondenței - - - - - - - - - Aplicații pentru gravitația cuantică - - - - - - Fenomenologie - - - - - - - - - Cosmologie - - - - - - Istorie - - - - - - - - - Rezultatele inițiale - - - - - - - - - Prima revoluție a supercorzilor - - - - - - - - - A doua revoluție a supercorzilor - - - - - - Critici - - - - - - - - - Numărul de soluții - - - - - - - - - Independența de fundal - - - - - - - - - Sociologia științei - - - 14.3 Teoria finală - - - - - - Antecedente istorice - - - - - - - - - De la Grecia antică la Einstein - - - - - - - - - Secolul al XX-lea și interacțiunile nucleare - - - - - - Fizica modernă - - - - - - - - - Secvența convențională a teoriilor - - - - - - - - - Teoria corzilor și teoria M - - - - - - - - - Gravitația cuantică în bucle - - - - - - - - - Alte încercări - - - - - - - - - Starea actuală - - - - - - Filosofia - - - - - - Argumente împotrivă - - - - - - - - - Teorema lui Gödel despre incompletență - - - - - - - - - Limitele fundamentale în precizie - - - - - - - - - Lipsa legilor fundamentale - - - - - - - - - Număr infinit de straturi de ceapă - - - - - - - - - Imposibilitatea calculului 15 Filosofia și interpretările mecanicii cuantice - - - Implicații filosofice - - - 15.1 Interpretări ale mecanicii cuantice - - - - - - Istoria interpretărilor - - - - - - Natura interpretării - - - - - - Provocări ale interpretărilor - - - - - - Pe scurt - - - - - - - - - Clasificarea adoptată de Einstein - - - - - - - - - Interpretarea de la Copenhaga - - - - - - - - - Multe lumi - - - - - - - - - Istorii consistente - - - - - - - - - Interpretarea de ansamblu - - - - - - - - - Teoria De Broglie-Bohm - - - - - - - - - Mecanica cuantică relațională - - - - - - - - - Interpretare tranzacțională - - - - - - - - - Mecanica stocastică - - - - - - - - - Teorii ale colapsului obiectiv - - - - - - - - - Conștiința cauzează colapsul (interpretarea von Neumann-Wigner) - - - - - - - - - Multe minți - - - - - - - - - Logica cuantică - - - - - - - - - Teoria informației cuantice - - - - - - - - - Interpretări modale ale teoriei cuantice - - - - - - - - - Teorii temporal simetrice - - - - - - - - - Teoriile ramificării spațiu-timpului - - - - - - - - - Alte interpretări - - - - - - Comparație - - - 15.2 Măsurători în mecanica cuantică - - - - - - Rezumat calitativ - - - - - - Cantități măsurabile ("observabile") ca operatori - - - - - - Probabilitățile de măsurare și colapsul funcțiilor de undă - - - - - - - - - Spectru discret, nondegenerat - - - - - - - - - Spectru continuu, nedegenerat - - - - - - - - - Spectre degenerate - - - 15.3 Matricea de densitate - - - - - - Stări pure și mixte - - - - - - Exemple de aplicații - - - 15.4 Interpretarea Von Neumann–Wigner - - - - - - Observația în mecanica cuantică - - - - - - Interpretarea - - - - - - Obiecții față de interpretare - - - - - - - - - Acceptarea - - - - - - - - - - - - Opinii ale pionierilor mecanicii cuantice 16 Perspective în mecanica cuantică - - - 16.1 Probleme rezolvate recent în fizică - - - 16.2 Probleme nerezolvate în fizică - - - 16.2.1 Fizica generală și mecanica cuantică - - - 16.2.2 Gravitația cuantică - - - 16.2.3 Fizica particulelor / Fizica energiilor înalte - - - 16.2.4 Fizica nucleară - - - 16.2.5 Fizica atomică, moleculară și optică - - - 16.2.6 Fizica plasmei Referințe Despre autor - - - Nicolae Sfetcu - - - - - - De același autor - - - - - - Contact Editura - - - MultiMedia Publishing -/- . 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We put forward a new, ‘coherentist’ account of quantum entanglement, according to which entangled systems are characterized by symmetric relations of ontological dependence among the component particles. We compare this coherentist viewpoint with the two most popular alternatives currently on offer—structuralism and holism—and argue that it is essentially different from, and preferable to, both. In the course of this article, we point out how coherentism might be extended beyond the case of entanglement and further articulated.

This article studies the quantum effect of the brain neuronal system on both normal and abnormal conscious states. It develops Plasma Brain Dynamics (PBD) to obtain a set of kinetic quantum-plasma Wigner-Poisson equations. The model is established under typical electrostatic and collision-free conditions in both the absence and presence of an external magnetic field. The quantum perturbation is solved analytically by employing a backward-mapping approach to the motion of electrons. Results expose that the quantum perturbation turns out to be zero (...) at normal conscious states; but no more than 11% of the classical perturbation under assumed abnormal situations like a sudden head trauma, mood disorder, etc. The introduction of the magnetic field does not influence the results. (shrink)

Some theories of quantum mechanical phenomena endorse wave function realism, according to which the physical space we inhabit is very different from the physical space we appear to inhabit. In this paper I explore an argument against wave function realism that appeals to a type of simplicity that, although often overlooked, plays a crucial role in scientific theory choice. The type of simplicity in question is simplicity of fit between the way a theory says the world is and the way (...) the world appears to be. This argument can be understood as one way of spelling out the so-called “incredulous stare objection” that is sometimes leveled against surprising metaphysical theories. (shrink)

Although written in Japanese, an overall picture of quantum physics is drawn, which would surely be useful for beginners as well as researchers of the humanities.

What are quantum entities? Is the quantum domain deterministic or probabilistic? Orthodox quantum theory (OQT) fails to answer these two fundamental questions. As a result of failing to answer the first question, OQT is very seriously defective: it is imprecise, ambiguous, ad hoc, non-explanatory, inapplicable to the early universe, inapplicable to the cosmos as a whole, and such that it is inherently incapable of being unified with general relativity. It is argued that probabilism provides a very natural solution to the (...) quantum wave/particle dilemma and promises to lead to a fully micro-realistic, testable version of quantum theory that is free of the defects of OQT. It is suggested that inelastic interactions may induce quantum probabilistic transitions. (shrink)

Two radically different views about time are possible. According to the first, the universe is three dimensional. It has a past and a future, but that does not mean it is spread out in time as it is spread out in the three dimensions of space. This view requires that there is an unambiguous, absolute, cosmic-wide "now" at each instant. According to the second view about time, the universe is four dimensional. It is spread out in both space and time (...) - in space-time in short. Special and general relativity rule out the first view. There is, according to relativity theory, no such thing as an unambiguous, absolute cosmic-wide "now" at each instant. However, we have every reason to hold that both special and general relativity are false. Not only does the historical record tell us that physics advances from one false theory to another. Furthermore, elsewhere I have shown that we must interpret physics as having established physicalism - in so far as physics can ever establish anything theoretical. Physicalism, here, is to be interpreted as the thesis that the universe is such that some unified "theory of everything" is true. Granted physicalism, it follows immediately that any physical theory that is about a restricted range of phenomena only, cannot be true, whatever its empirical success may be. It follows that both special and general relativity are false. This does not mean of course that the implication of these two theories that there is no unambiguous cosmic-wide "now" at each instant is false. It still may be the case that the first view of time, indicated at the outset, is false. Are there grounds for holding that an unambiguous cosmic-wide "now" does exist, despite special and general relativity, both of which imply that it does not exist? There are such grounds. Elsewhere I have argued that, in order to solve the quantum wave/particle problem and make sense of the quantum domain we need to interpret quantum theory as a fundamentally probabilistic theory, a theory which specifies how quantum entities - electrons, photons, atoms - interact with one another probabilistically. It is conceivable that this is correct, and the ultimate laws of the universe are probabilistic in character. If so, probabilistic transitions could define unambiguous, absolute cosmic-wide "nows" at each instant. It is entirely unsurprising that special and general relativity have nothing to say about the matter. Both theories are pre-quantum mechanical, classical theories, and general relativity in particular is deterministic. The universe may indeed be three dimensional, with a past and a future, but not spread out in four dimensional space-time, despite the fact that relativity theories appear to rule this out. These considerations, finally, have implications for views about the arrow of time and free will. (shrink)

The purpose of this book is to explain Quantum Bayesianism (‘QBism’) to “people without easy access to mathematical formulas and equations” (4-5). Qbism is an interpretation of quantum mechanics that “doesn’t meddle with the technical aspects of the theory [but instead] reinterprets the fundamental terms of the theory and gives them new meaning” (3). The most important motivation for QBism, enthusiastically stated on the book’s cover, is that QBism provides “a way past quantum theory’s paradoxes and puzzles” such that much (...) of the weirdness associated with quantum theory “dissolves under the lens of QBism”. (shrink)

The title of Kastner’s article is “Beyond Complementarity” (R. E. Kastner 6 March 2016 Foundations of Physics Group, University of Maryland, College Park, USA) -/- In this paper, there are quite many ideas similar to my ideas. The main ideas are the following: -/- - Bohr’s complementarity does not work: “’Complementarity’ cannot consistently account for the emergence of classicality from the quantum level (p. 1) - It is argued that ultimately this problem arises from Bohr’s implicit assumption that all quantum (...) evolution is unitary; i.e., that there is no real, physical non-unitary collapse. (p. 1) -/- In my works 2002-2008 and later (2010-2106), I argued exactly the same ideas. The non-unitary phenomena in quantum and in the relationship between quantum and classical phenomena means exactly the EDWs! -/- Our world of experience is clearly classical in that we can legitimately consider our lab and macroscopic measuring instruments as inhabiting a well-defined inertial frame. But these are the very phenomena that cry out for explanation in view of that fact that the microscopic quantum objects upon which we experiment, according to the theory describing them, do not inhabit well-defined reference frames. (pp. 3-4) -/- “Our world of experience” means exactly the macro-EW vs. the micro-EW. However, we have to pay attention that “quantum world” means the micro-EW (for particles) and the wave-EW. In section 4, Kastner investigates the “unnecessary” Bohr’s “epistemological and methodological assumptions”. If the reader will read the entire section will have the sensation of reading one of my works! In 2007, and 2008, I analyzed exactly the same notions with almost the same verdict! (shrink)

Causal modelling provides a powerful set of tools for identifying causal structure from observed correlations. It is well known that such techniques fail for quantum systems, unless one introduces 'spooky' hidden mechanisms. Whether one can produce a genuinely quantum framework in order to discover causal structure remains an open question. Here we introduce a new framework for quantum causal modelling that allows for the discovery of causal structure. We define quantum analogues for core features of classical causal modelling techniques, including (...) the causal Markov condition and faithfulness. Based on the process matrix formalism, this framework naturally extends to generalised structures with indefinite causal order. (shrink)

Definitions I presented in a previous article as part of a semantic approach in epistemology assumed that the concept of derivability from standard logic held across all mathematical and scientific disciplines. The present article argues that this assumption is not true for quantum mechanics (QM) by showing that concepts of validity applicable to proofs in mathematics and in classical mechanics are inapplicable to proofs in QM. Because semantic epistemology must include this important theory, revision is necessary. The one I propose (...) also extends semantic epistemology beyond the ‘hard’ sciences. The article ends by presenting and then refuting some responses QM theorists might make to my arguments. (shrink)

Students often invoke quantum mechanics in class or papers to make philosophical points. This tendency has been encouraged by pop culture influences like the film What the Bleep do We Know? There is little merit to most of these putative implications. However, it is difficult for philosophy teachers unfamiliar with quantum mechanics to handle these supposed implications in a clear and careful way. This paper is a philosophy of science version of MythBusters. We offer a brief primer on the nature (...) of quantum mechanics, enumerate nine of the most common implications associated with quantum mechanics, and finally clarify each implication with the facts. Our goal is to explain what quantum mechanics doesn’t show. (shrink)

La mécanique quantique est une théorie physique contemporaine réputée pour ses défis au sens commun et ses paradoxes. Depuis bientôt un siècle, plusieurs interprétations de la théorie ont été proposées par les physiciens et les philosophes, offrant des images quantiques du monde, ou des ontologies, radicalement différentes. L'existence d'un hasard fondamental, ou d'une multitude de mondes en-dehors du nôtre, dépend ainsi de l'interprétation adoptée. Après avoir discuté de la définition de l'interprétation d'une théorie physique, ce livre présente trois principales interprétations (...) quantiques, empiriquement équivalentes : l'interprétation dite orthodoxe, l'interprétation de Bohm, et l'interprétation des mondes multiples. Des textes d'Albert & Galchen, ainsi que de Mermin, présentent le concept de non-localité et invitent à une analyse de l'argument d'Einstein-Podolsky-Rosen et du théorème de Bell. (shrink)