Wave-Particle Duality

In this paper, I critically assess different interpretations of Bohmian mechanics that are not committed to an ontology based on the wave function being an actual physical object that inhabits configuration space. More specifically, my aim is to explore the connection between the denial of configuration space realism and another interpretive debate that is specific to Bohmian mechanics: the quantum potential versus guidance approaches. Whereas defenders of the quantum potential approach to the theory claim that Bohmian mechanics is better formulated (...) as quasi-Newtonian, via the postulation of forces proportional to acceleration; advocates of the guidance approach defend the notion that the theory is essentially first-order and incorporates some concepts akin to those of Aristotelian physics. Here I analyze whether the desideratum of an interpretation of Bohmian mechanics that is both explanatorily adequate and not committed to configuration space realism favors one of these two approaches to the theory over the other. Contrary to some recent claims in the literature, I argue that the quasi-Newtonian approach based on the idea of a quantum potential does not come out the winner. (shrink)

Simultaneous observation of the wave-like and particle-like aspects of the photon in the double-slit experiment is unallowed. The underlying reason behind this limitation is not understood. In this paper, we explain this unique behavior by considering the communicational properties of the photons. Photons have three independently adjustable properties (energy, direction, and spin) that can be used to communicate messages. The double-slit experiment setup fixes two of these properties and confines the single photon’s capacity for conveying messages to no more than (...) one message. With such a low communication capacity, information theory dictates that measurements associated only with one proposition can obtain consistent results, and a second measurement associated with an independent proposition must necessarily lead to randomness. In the double-slit example, these are the wave or particle properties of the photon. The interpretation we offer is based on the formalism of information theory and does not make use of Heisenberg’s uncertainty relation in any form. (shrink)

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)

Interference of more and more massive objects provides a spectacular confirmation of quantum theory. It is usually regarded as support for “wave–particle duality” and in an extension of this duality even as support for “complementarity”. We first give an outline of the historical development of these notions. Already here it becomes evident that they are hard to define rigorously, i.e. have mainly a heuristic function. Then we discuss recent interference experiments of large and complex molecules which seem to support this (...) heuristic function of “duality”. However, we show that in these experiments the diffraction of a delocalized center-of-mass wave function depends on the interaction of the localized structure of the molecule with the diffraction element. Thus, the molecules display “dual features” at the same time, which contradicts the usual understanding of wave–particle duality. We conclude that the notion of “wave–particle duality” deserves no place in modern quantum physics. (shrink)

A prominent way through which wave-particle duality has been ascribed to photons is by illustrating their “wave-like” behaviour in the Mach-Zehnder interferometer and “particle-like” behaviour in the anti-correlation experiment. This duality has been formulated in two ways. Some have based the claim on the complementarity principle. This formulation, however, has already been shown to be problematic. Others have made a much simpler duality claim by considering that single-photons are analogous to waves and particles in the above experiments. I criticise this (...) formulation by arguing that the analogies cannot be distinctly established. Thus, this duality claim is found to be unsubstantiated. (shrink)

The traditional analysis of the basic version of the double-slit experiment leads to the conclusion that wave-particle duality is a fundamental fact of nature. However, such a conclusion means to imply that we are not only required to have two contradictory pictures of reality but also compelled to abandon the objectiveness of the truth values, “true” and “false”. Yet, even if we could accept wave-like behavior of quantum particles as the best explanation for the build-up of an interference pattern in (...) the double-slit experiment, without the objectivity of the truth values we would never have certainty regarding any statement about the world. The present paper discusses ways to reconcile the correct description of the double-slit experiment with the objectiveness of “true” and “false”. (shrink)

Quantum Counterfactual Communication is the recently-proposed idea of using quantum physics to send messages between two parties, without any matter/energy transfer associated with the bits sent. While this has excited massive interest, both for potential ‘unhackable’ communication, and insight into the foundations of quantum mechanics, it has been asked whether this process is essentially quantum, or could be performed classically. We examine counterfactual communication, both classical and quantum, and show that the protocols proposed so far for sending signals that don’t (...) involve matter/energy transfer associated with the bits sent must be quantum, insofar as they require wave-particle duality. (shrink)

Niels Bohr was a central figure in quantum physics, well known for his work on atomic structure and his contributions to the Copenhagen interpretation of quantum mechanics. In this book, philosopher of science Slobodan Perović explores the way Bohr practiced and understood physics, and analyzes its implications for our understanding of modern science. Perović develops a novel approach to Bohr’s understanding of physics and his method of inquiry, presenting an exploratory symbiosis of historical and philosophical analysis that uncovers the key (...) aspects of Bohr’s philosophical vision of physics within a given historical context. -/- To better understand the methods that produced Bohr’s breakthrough results in quantum phenomena, Perović clarifies the nature of Bohr’s engagement with the experimental side of physics and lays out the basic distinctions and concepts that characterize his approach. Rich and insightful, Perović’s take on the early history of quantum mechanics and its methodological ramifications sheds vital new light on one of the key figures of modern physics. (shrink)

Scientific realism is the view that our best scientific theories can be regarded as (approximately) true. This is connected with the view that science, physics in particular, and metaphysics could (and should) inform one another: on the one hand, science tells us what the world is like, and on the other hand, metaphysical principles allow us to select between the various possible theories which are underdetermined by the data. Nonetheless, quantum mechanics has always been regarded as, at best, puzzling, if (...) not contradictory. As such, it has been considered for a long time at odds with scientific realism, and thus a naturalized quantum metaphysics was deemed impossible. Luckily, now we have many quantum theories compatible with a realist interpretation. However, scientific realists assumed that the wave-function, regarded as the principal ingredient of quantum theories, had to represent a physical entity, and because of this they struggled with quantum superpositions. In this paper I discuss a particular approach which makes quantum mechanics compatible with scientific realism without doing that. In this approach, the wave-function does not represent matter which is instead represented by some spatio-temporal entity dubbed the primitive ontology: point-particles, continuous matter fields, space-time events. I argue how within this framework one develops a distinctive theory-construction schema, which allows to perform a more informed theory evaluation by analyzing the various ingredients of the approach and their inter-relations. (shrink)

Because an unmeasured quantum system consists of information — neither tangible existence nor its complete absence — no property can be assigned a definite value, only a range of likely values should it be measured. The instantaneous transition from information to matter upon measurement establishes a gradient between being and not-being. A quantum system enters a determinate state in a particular moment until this moment is past, at which point the system resumes its default state as an evolving superposition of (...) potential values of properties, neither strictly being nor not-being. Like a “self-organized” chemical system that derives energy from breaking down environmental gradients, a quantum system derives information from breaking down the ontological gradient. An organism is a body in the context of energy and a mind in the context of information. (shrink)

A recent series of experiments have demonstrated that a classical fluid mechanical system, constituted by an oil droplet bouncing on a vibrating fluid surface, can be induced to display a number of behaviours previously considered to be distinctly quantum. To explain this correspondence it has been suggested that the fluid mechanical system provides a single-particle classical model of de Broglie’s idiosyncratic ‘double solution’ pilot wave theory of quantum mechanics. In this paper we assess the epistemic function of the bouncing oil (...) droplet experiments in relation to quantum mechanics. We find that the bouncing oil droplets are best conceived as an analogue illustration of quantum phenomena, rather than an analogue simulation, and, furthermore, that their epistemic value should be understood in terms of how-possibly explanation, rather than confirmation. Analogue illustration, unlike analogue simulation, is not a form of ‘material surrogacy’, in which source empirical phenomena in a system of one kind can be understood as ‘standing in for’ target phenomena in a system of another kind. Rather, analogue illustration leverages a correspondence between certain empirical phenomena displayed by a source system and aspects of the ontology of a target system. On the one hand, this limits the potential inferential power of analogue illustrations, but, on the other, it widens their potential inferential scope. In particular, through analogue illustration we can learn, in the sense of gaining how-possibly understanding, about the putative ontology of a target system via an experiment. As such, the potential scientific value of these extraordinary experiments is undoubtedly a significant one. (shrink)

The assertion that an experiment by Afshar et al. demonstrates violation of Bohr’s Principle of Complementarity is based on the faulty assumption that which-way information in a double-slit interference experiment can be retroactively determined from a future measurement.

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)

According to our understanding of the everyday physical world, observable phenomena are underpinned by persistent objects that can be reidentified across time by observation of their distinctive properties. This understanding is reflected in classical mechanics, which posits that matter consists of persistent, reidentifiable particles. However, the mathematical symmetrization procedures used to describe identical particles within the quantum formalism have led to the widespread belief that identical quantum particles lack either persistence or reidentifiability. However, it has proved difficult to reconcile these (...) assertions with the fact that identical particles are routinely assumed to be reidentifiable in particular circumstances. For example, when two electrons move through a bubble chamber, each is said to generate a sequence of bubbles that is caused by one and the same particle. Moreover, neither of these assertions accounts for the mathematical form of the symmetrization procedures used to describe identical particles within the quantum framework, leaving open theoretical possibilities other than bosonic and fermionic behavior, such as paraparticles, which do not appear to be realized in nature. Here we propose the novel idea that both persistence and nonpersistence models must be employed in order to fully account for the behaviour of identical particles. Thus, identical particles are neither persistent nor nonpersistent. We prove the viability of this viewpoint by showing how Feynman's and Dirac's symmetrization procedures arise through a synthesis of a quantum treatment of these models, and by showing how reidentifiability emerges in a context-dependent manner. We further show that the persistence and nonpersistence models satisfy the key characteristics of Bohr's concept of complementarity, and thereby propose that the behavior of identical particles is a manifestation of a persistence-nonpersistence complementarity, analogous to Bohr's wave-particle complementarity for individual particles. Finally, we construct a precise parallel between these two complementarities, and detail their conceptual similarities and dissimilarities. (shrink)

Weak/strong duality is usually accompanied by what seems a puzzling ontological feature: the fact that under this kind of duality what is viewed as 'elementary' in one description gets mapped to what is viewed as 'composite' in the dual description. This paper investigates the meaning of this apparent 'particle democracy', as it has been called, by adopting an historical approach. The aim is to clarify the nature of the correspondence between 'dual particles' in the light of an historical analysis of (...) the developments of the idea of weak/strong duality, starting with Dirac's electric-magnetic duality and its successive generalizations in the context of field theory, to arrive at its first extension to string theory. This analysis is then used as evidential basis for discussing the 'elementary/composite' divide and, after taking another historical detour by analysing an instructive analogy case, drawing some conclusions on the particle-democracy issue. (shrink)

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)

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)

The notion of equality between two observables will play many important roles in foundations of quantum theory. However, the standard probabilistic interpretation based on the conventional Born formula does not give the probability of equality between two arbitrary observables, since the Born formula gives the probability distribution only for a commuting family of observables. In this paper, quantum set theory developed by Takeuti and the present author is used to systematically extend the standard probabilistic interpretation of quantum theory to define (...) the probability of equality between two arbitrary observables in an arbitrary state. We apply this new interpretation to quantum measurement theory, and establish a logical basis for the difference between simultaneous measurability and simultaneous determinateness. (shrink)

It is an experimental fact that \ -decays produce in a cloud chamber at most one track and that this track points in a random direction. This seems to contradict the description of decay in Quantum Mechanics: according to Gamow a spherical wave is produced and moves radially according to Schrödinger’s equation. It is as if the interaction with the supersaturated vapor turned the wave into a particle. The aim of this note is to place this effect in the context (...) of Schrödinger’s Quantum Mechanics. We shall see that the properties of the initial wave function suggest the introduction of a semiclassical formalism in which the \ -wave can be described as a collection of semiclassical wavelets; each of them interacts with an atom and forms an entangled state. The interaction can be regarded as a semiclassical inelastic scattering event. The measurement selects the wave function of one of the ions, with a probability given by Born’s rule. This ion interacts with the atoms nearby leading to the formation of a droplet. One can reasonably assume that also the wavelet entangled with the selected ion has probability one to remain as part of the description of the system. The measurement process is therefore represented by a unitary operator. The wavelet remains sharply localized on a classical path \ It is still a probability wave: it determines the probability that another atom be ionized. This probability is essentially zero unless the atom lies on \ . This gives the visible track. (shrink)

Since its discovery in 1912, X-ray crystallography has become a most useful tool in physics, chemistry, material science, mineralogy, metallurgy, and even in the biological sciences. In 1914, Max von Laue was awarded the Nobel Prize “for the discovery of X-ray diffraction by crystals,” followed by the 1915 Nobel Prize to William Henry Bragg and William Lawrence Bragg “for their services in analysis of crystal structure by means of X-rays.” And these early Nobel prizes marked only the beginning of X-ray (...) crystallography as one of the most fruitful methods in the history of modern science. A 100 years after Laue’s Nobel Prize and 50 years after another Nobel Prize to Dorothy Hodgkin “for her determination by X-ray technique of the structures of important biochemical substances,” the UN proclaimed 2014 the International Year of Crystallography. “In all, 45 scientists have been awarded over the past century for work that is either directly or indirectly related to crystallo .. (shrink)

In my 2013 article, “A New Theory of Free Will”, I argued that several serious hypotheses in philosophy and modern physics jointly entail that our reality is structurally identical to a peer-to-peer (P2P) networked computer simulation. The present paper outlines how quantum phenomena emerge naturally from the computational structure of a P2P simulation. §1 explains the P2P Hypothesis. §2 then sketches how the structure of any P2P simulation realizes quantum superposition and wave-function collapse (§2.1.), quantum indeterminacy (§2.2.), wave-particle duality (§2.3.), (...) and quantum entanglement (§2.4.). Finally, §3 argues that although this is by no means a philosophical proof that our reality is a P2P simulation, it provides ample reasons to investigate the hypothesis further using the methods of computer science, physics, philosophy, and mathematics. (shrink)

We describe a new class of experiments designed to probe the foundations of quantum mechanics. Using quantum controlling devices, we show how to attain a freedom in temporal ordering of the control and detection of various phenomena. We consider wave–particle duality in the context of quantum-controlled and the entanglement-assisted delayed-choice experiments. Then we discuss a quantum-controlled CHSH experiment and measurement of photon’s transversal position and momentum in a single set-up.

The notion of uncertainty in the description of a physical system has assumed prodigious importance in the development of quantum theory. Overcoming the early misunderstanding and confusion, the concept grew continuously and still remains an active and fertile research field. Curious new insights and correlations are gained and developed in the process with the introduction of new ‘measures’ of uncertainty or indeterminacy and the development of quantum measurement theory. In this article we intend to reach a fairly uptodate status report (...) of this yet unfurling concept and its interrelation with some distinctive quantum features like nonlocality, steering and entanglement/inseparability. Some recent controversies are discussed and the grey areas are mentioned. (shrink)

Book Review of: Dow We Really Understand Quantum Mechanics? by Franck Laloe.

The aim of this dissertation is to clarify the debate over the explanation of quantum speedup and to submit, for the reader's consideration, a tentative resolution to it. In particular, I argue, in this dissertation, that the physical explanation for quantum speedup is precisely the fact that the phenomenon of quantum entanglement enables a quantum computer to fully exploit the representational capacity of Hilbert space. This is impossible for classical systems, joint states of which must always be representable as product (...) states. I begin the dissertation by considering, in Chapter 2, the most popular of the candidate physical explanations for quantum speedup: the many worlds explanation of quantum computation. I argue that, although it is inspired by the neo-Everettian interpretation of quantum mechanics, unlike the latter it does not have the conceptual resources required to overcome objections such as the so-called `preferred basis objection'. I further argue that the many worlds explanation, at best, can serve as a good description of the physical process which takes place in so-called network-based computation, but that it is incompatible with other models of computation such as cluster state quantum computing. I next consider, in Chapter 3, a common component of most other candidate explanations of quantum speedup: quantum entanglement. I investigate whether entanglement can be said to be a necessary component of any explanation for quantum speedup, and I consider two major purported counter-examples to this claim. I argue that neither of these, in fact, show that entanglement is unnecessary for speedup, and that, on the contrary, we should conclude that it is. In Chapters 4 and 5 I then ask whether entanglement can be said to be sufficient as well. In Chapter 4 I argue that despite a result that seems to indicate the contrary, entanglement, considered as a resource, can be seen as sufficient to enable quantum speedup. Finally, in Chapter 5 I argue that entanglement is sufficient to explain quantum speedup as well. (shrink)

Prologue: Stormclouds : London, April 1900 -- Quantum of action: The most strenuous work of my life : Berlin, December 1900 ; Annus Mirabilis : Bern, March 1905 ; A little bit of reality : Manchester, April 1913 ; la Comédie Française : Paris, September 1923 ; A strangely beautiful interior : Helgoland, June 1925 ; The self-rotating electron : Leiden, November 1925 ; A late erotic outburst : Swiss Alps, Christmas 1925 -- Quantum interpretation: Ghost field : Oxford, August (...) 1926 ; All this damned quantum jumping : Copenhagen, October 1926 ; The uncertainty principle : Copenhagen, February 1927 ; The 'Kopenhagener geist' : Copenhagen, June 1927 ; There is no quantum world : Lake Como, September 1927 -- Quantum debate: The debate commences : Brussels, October 1927 ; An absolute wonder : Cambridge, Christmas 1927 ; The photon box : Brussels, October 1930 ; A bolt from the blue : Princeton, May 1935 ; The paradox of Schrödinger's cat : Oxford, August 1935 -- Interlude: The first war of physics : Christmas 1938-August 1945 -- Quantum fields: Shelter Island : Long Island, June 1947 ; Pictorial semi-vision thing : New York, January 1949 ; A beautiful idea : Princeton, February 1954 ; Some strangeness in the proportion : Rochester, August 1960 ; Three quarks for Muster Mark! : New York, March 1963 ; The 'God particle' : Cambridge, Massachusetts, Autumn 1967 -- Quantum particles: Deep inelastic scattering : Stanford, August 1968 ; Of charm and weak neutral currents : Harvard, February 1970 ; The magic of colour : Princeton/Harvard, April 1973 ; The November revolution : Long Island/Stanford, November 1974 ; Intermediate vector bosons : Geneva, January/June 1983 ; The standard model : Geneva, September 2003 -- Quantum reality: Hidden variable : Princeton, Spring 1951 ; Bertlmann's socks : Boston, September 1964 ; The Aspect experiments : Paris, September 1982 ; The quantum eraser : Baltimore, January 1999 ; Lab cats : Stony Brook/Delft, July 2000 ; The persistent illusion : Vienna, December 2006 -- Quantum cosmology: The wavefunction of the universe : Princeton, July 1966 ; Hawking radiation : Oxford, February 1974 ; The first superstring revolution : Aspen, August 1984 ; Quanta of space and time : Santa Barbara, February 1986 ; Crisis? What crisis? : Durham, Summer 1994 -- A quantum of solace? : Geneva, March 2010. (shrink)

In spite of the interference manifested in the double-slit experiment, quantum theory predicts that a measure of interference defined by Sorkin and involving various outcome probabilities from an experiment with three slits, is identically zero. We adapt Sorkin’s measure into a general operational probabilistic framework for physical theories, and then study its relationship to the structure of quantum theory. In particular, we characterize the class of probabilistic theories for which the interference measure is zero as ones in which it is (...) possible to fully determine the state of a system via specific sets of ‘two-slit’ experiments. (shrink)

A growing number of commentators have, in recent years, noted the important affinities in the views of Immanuel Kant and Niels Bohr. While these commentators are correct, the picture they present of the connections between Bohr and Kant is painted in broad strokes; it is open to the criticism that these affinities are merely superficial. In this essay, I provide a closer, structural, analysis of both Bohr's and Kant's views that makes these connections more explicit. In particular, I demonstrate the (...) similarities between Bohr's argument, on the one hand, that neither the wave nor the particle description of atomic phenomena pick out an object in the ordinary sense of the word, and Kant's requirement, on the other hand, that both ‘mathematical’ (having to do with magnitude) and ‘dynamical’ (having to do with an object's interaction with other objects) principles must be applicable to appearances in order for us to determine them as objects of experience. I argue that Bohr's ‘complementarity interpretation’ of quantum mechanics, which views atomic objects as idealizations, and which licenses the repeal of the principle of causality for the domain of atomic physics, is perfectly compatible with, and indeed follows naturally from a broadly Kantian epistemological framework. (shrink)

I review arguments demonstrating how the concept of “particle” numbers arises in the form of equidistant energy eigenvalues of coupled harmonic oscillators representing free fields. Their quantum numbers (numbers of nodes of the wave functions) can be interpreted as occupation numbers for objects with a formal mass (defined by the field equation) and spatial wave number (“momentum”) characterizing classical field modes. A superposition of different oscillator eigenstates, all consisting of n modes having one node, while all others have none, defines (...) a non-degenerate “n-particle wave function”. Other discrete properties and phenomena (such as particle positions and “events”) can be understood by means of the fast but continuous process of decoherence: the irreversible dislocalization of superpositions. Any wave-particle dualism thus becomes obsolete. The observation of individual outcomes of this decoherence process in measurements requires either a subsequent collapse of the wave function or a “branching observer” in accordance with the Schrödinger equation—both possibilities applying clearly after the decoherence process. Any probability interpretation of the wave function in terms of local elements of reality, such as particles or other classical concepts, would open a Pandora’s box of paradoxes, as is illustrated by various misnomers that have become popular in quantum theory. (shrink)

'Particle or Wave' explains the origins and development of modern physical concepts about matter and the controversies surrounding them.

In 1909, Einstein derived a formula for the mean square energy fluctuation in blackbody radiation. This formula is the sum of a wave term and a particle term. In a key contribution to the 1926 Dreim¨.

We respond to criticism of our paper “Paradox in Wave-Particle Duality for Non-Perturbative Measurements”. We disagree with Steuernagel’s derivation of the visibility of the Afshar experiment. To calculate the fringe visibility, Steuernagel utilizes two different experimental situations, i.e. the wire grid in the pattern minima and in the pattern maxima. In our assessment, this procedure cannot lead to the correct result for the complementarity properties of a wave-particle in one particular experimental set-up.

In previous work, a non-standard theory of probability was formulated and used to systematize interference effects involving the simplest type of quantum systems. The main result here is a self-contained, non-trivial generalization of that theory to capture interference effects involving a much broader range of quantum systems. The discussion also focuses on interpretive matters having to do with the actual/virtual distinction, non-locality, and conditional probabilities.

In the previous article (Found. Phys. Lett. 16:325–341, 2003), we showed that a reciprocity of the Gauss sums is connected with the wave and particle complementary. In this article, we revise the previous investigation by considering a relation between the Gauss optics and the Gauss sum based upon the recent studies of the Weil representation for a finite group.

We report on the simultaneous determination of complementary wave and particle aspects of light in a double-slit type “welcher-weg” experiment beyond the limitations set by Bohr’s Principle of Complementarity. Applying classical logic, we verify the presence of sharp interference in the single photon regime, while reliably maintaining the information about the particular pinhole through which each individual photon had passed. This experiment poses interesting questions on the validity of Complementarity in cases where measurements techniques that avoid Heisenberg’s uncertainty principle and (...) quantum entanglement are employed. We further argue that the application of classical concepts of waves and particles as embodied in Complementarity leads to a logical inconsistency in the interpretation of this experiment. (shrink)

Why do photons and speeding electrons have both wave features and particle features when common sense tells us that they should be either particle or wave and not an amalgam of both? Part I of this paper deals with photons and argues that there are flaws in the assumptions we have made regarding their particle nature. The argument depends upon distinguishing between two identities of the photon, namely unstored energy and its stored (relativistic) mass. Part II extends these arguments to (...) the case of the speeding electron and argues that current ontological assumptions made about projectiles have exacerbated our confusion about the nature of moving electrons. When regarded ontologically, projectile motion is not as simple as has been assumed by both classical and modern physics. (shrink)

The Einstein-Rupp experiments were proposed in 1926 by Albert Einstein to study the wave versus particle nature of light. Einstein presented a theoretical analysis of these experiments to the Berlin Academy together with results of Emil Rupp, who claimed to have successfully carried them out. However, as the preceding paper has shown, Rupp's success was the result of scientific fraud. This paper will argue, after exploring their interpretation, that the experiments were a relevant part of the background to such celebrated (...) contributions to quantum mechanics as Born’s statistical interpretation of the wave function and Heisenberg’s uncertainty principle. Yet, the Einstein-Rupp experiments have hardly received attention in the history of quantum mechanics literature. In part, this is a consequence of self-censorship in the physics community, enforced in the wake of the Rupp affair. Self-censorship among historians of physics may however also have played a role. (shrink)

Introduction The digital age has revolutionized the way we think, communicate, work, and enjoy life. Technology has increased the pace of life at an ...

The electron double-slit interference is re-examined from the point of view of temporal topos. Temporal topos (or t-topos) is an abstract algebraic (categorical) method using the theory of sheaves. A brief introduction to t-topos is given. When the structural foundation for describing particles is based on t-topos, the particle-wave duality of electron is a natural consequence. A presheaf associated with the electron represents both particle-like and wave-like properties depending upon whether an object in the site (t-site) is specified (particle-like) or (...) not (wave-like). It is shown that the localization of the electron at one of the slits is equivalent to choosing a particular object in the t-site and that the electron behaves as a wave when it passes through a double-slit because there are more than one object in the t-site. Also, the single-slit diffraction is interpreted as a result of the possibility of many different ways of factoring a morphism between two objects. (shrink)

Quantum mechanics is formulated as a geometric theory on a Hilbert manifold. Images of charts on the manifold are allowed to belong to arbitrary Hilbert spaces of functions including spaces of generalized functions. Tensor equations in this setting, also called functional tensor equations, describe families of functional equations on various Hilbert spaces of functions. The principle of functional relativity is introduced which states that quantum theory (QT) is indeed a functional tensor theory, i.e., it can be described by functional tensor (...) equations. The main equations of QT are shown to be compatible with the principle of functional relativity. By accepting the principle as a hypothesis, we then explain the origin of physical dimensions, provide a geometric interpretation of Planck’s constant, and find a simple model of the two-slit experiment and the process of measurement. (shrink)

Well known quantum and time paradoxes, and the difficulty to derive the second law of thermodynamics, are proposed to be the result of our historically grown paradigm for energy: it is just there, the capacity to do work, not directly related to change. When the asymmetric nature of energy is considered, as well as the involvement of energy turnover in any change, so that energy can be understood as fundamentally "dynamic", and time-oriented (new paradigm), these paradoxes and problems dissolve. The (...) most basic consequence concerns the particle-wave dualism. For a reversible inter-conversion of a particle into a wave, subject to a dynamic energy, a self-image of information has to be generated: quantum theory has to be complemented by a theory of information. Then, quantum processes can be derived from classical ones and the second law of thermodynamics with the tendency of increasing entropy follows in a straightforward way. (shrink)

When Einstein formulated his special relativity, he developed his dynamics for point particles. Of course, many valiant efforts have been made to extend his relativity to rigid bodies, but this subject is forgotten in history. This is largely because of the emergence of quantum mechanics with wave-particle duality. Instead of Lorentz-boosting rigid bodies, we now boost waves and have to deal with Lorentz transformations of waves. We now have some nderstanding of plane waves or running waves in the covariant picture, (...) but we do not yet have a clear picture of standing waves. In this report, we show that there is one set of standing waves which can be Lorentz-transformed while being consistent with all physical principle of quantum mechanics and relativity. It is possible to construct a representation of the Poincaré group using harmonic oscillator wave functions satisfying space-time boundary conditions. This set of wave functions is capable of explaining the quantum bound state for both slow and fast hadrons. In particular it can explain the quark model for hadrons at rest, and Feynman’s parton model hadrons moving with a speed close to that of light. (shrink)