Geometric underdetermination (i.e., the underdetermination of the geometric properties of space and time) is a live possibility in light of some of our best theories of physics. In response to this, geometric conventionalism offers a selective anti-realism, refusing to assign truth values to variant geometric propositions. Although often regarded as being dead in the water by modern philosophers, in this article we propose to revitalise the programme of geometric conventionalism both on its own terms, and as an attractive response to (...) the above-mentioned live cases of geometric underdetermination. Specifically, we (1) articulate geometrical conventionalism as we conceive it, (2) anticipate various objections to the view, and defend it against those objections, and (3) demonstrate how geometric conventionalism plays out in the context of a wide variety of spacetime theories, both classical and relativistic. (shrink)

We critically examine the role and status probabilities, as they enter via the Quantum Equilibrium Hypothesis, play in the standard, deterministic interpretation of deBroglie’s and Bohm’s Pilot Wave Theory (dBBT), by considering interpretations of probabilities in terms of ignorance, typicality and Humean Best Systems, respectively. We argue that there is an inherent conflict between dBBT and probabilities, thus construed. The conflict originates in dBBT’s deterministic nature, rooted in the Guidance Equation. Inquiring into the latter’s role within dBBT, we find it (...) explanatorily redundant (in particular for dBBT’s solution of the Measurement Problem, which only requires that the corpuscles possess definite positions), and subject to a number of difficulties. Following a suggestion from Bell, we propose to abandon the Guidance Equation, whilst retaining dBBT’s point particle-based Primitive Ontology, with positions as local beables. The resultant theory, which we identify as a stochastic, minimally deBroglie-Bohmian theory, describes a random walk through configuration space. Its probabilities, we propose, are best understood as dispositions of possible corpuscle configurations to manifest themselves. We subsequently evaluate the merits of sdBBT vis-à-vis dBBT, such as the justification of the Symmetrisation Postulate and the violation of the Action-Reaction Principle. Not only is sdBBT an attractive Bohmian theory that, whilst retaining dBBT's virtues, overcomes many of its shortcomings; it also sparks off a number of exciting follow-up questions, such as a comparison between sdBBT and other stochastic hidden-variable theories, e.g. Nelson Stochastics, or between sdBBT and the Everett interpretation. (shrink)

Segundo as descobertas da Física Moderna (Física Quántica), Realidade (Wirklichkeit em Alemão) não é mais o real que nos é familiar e tangível (cousal), mas algo bem diferente, tanto espacial como temporalmente, algo claramente mais aberto. Trata-se de algo holístico, uma Gestalt de carácter a-material, uma relação depura inter-conexão ("a-dvaita"), uma potencialidade inseparável, similar ao amor espiritual e omnicompreensivo. Ou seja, segundo o autor, a realidade está possuída por uma tonalidade processual, uma inspiração holística e intimamente conectada, uma transformação, um (...) processo contínuo de criação e aniquilamento, com o potencial de se manifestar a si mesma de um modo em que predomina uma essencial complementaridade dual energético-material. Assim, para o autor do artigo, o mundo em que vivemos, Wirklichkeit, não pode ser propriamente compreendido em termos puramente ontológicos. Segundo o autor, a questão : O que é, o que é que existe? torna-se uma questão desprovida de sentido. Em sua opinião, admissíveis seriam apenas questões acerca do que propriamente actua (wirkt), do que acontece, do que conecta, ou, por outras palavras, a questão do "entre". Consequentemente, a evolução no tempo e no espaço não procede mais de leis causais estritamente determinadas, pois o que existe são apenas tendências gerais intrínsecas (expectações), caracterizadas por probabilidades relativas a uma infinidade de realizações possíveis, as quais em média, pelo processo de sobreposições descoerentes, nos fazem voltar à nossa concepção comum do mundo como sendo uma realidade tangível dominada por leis naturais rigorosa e universalmente válidas. /// According to the findings of modern physics (quantum physics) Reality (in German more appropriate: Wirklichkeitj is basically no more the familiar, tangible (thing-like) reality but quite different and, spatially and temporally, more open. It is a holistic a-material "Gestalt", a pure connectedness ("a-dvaita"), an inseparable potentiality, similar to the spiritual and to all-embracing love. It relates to a processlike holistic and intimately connected inspiration and transformation, a continuous creation and annihilation, with the potential manifesting itself with some vagueness in complementary dual and essentially energetic/material diversified fashion. Hence, for the author, the world in which we are living, Wirklichkeit, cannot be understood strictly in an ontological way. The question: What is, what exists? becomes meaningless. Questions still admissible are: What acts (wirkt), happens, binds?, the question for the "in-between". The evolution in time does not follow anymore from strictly determined causal laws but there are only general intrinsic tendencies ("expectations"), characterised by probabilities for infinitely many possible realizations, which on average (decoherent superpositions) lead back to our familiar conception of the world as an objective tangible reality with its rigorously valid natural laws. (shrink)

How to compute the probability distribution of a detection time, i.e., of the time which a detector registers as the arrival time of a quantum particle, is a long-debated problem. In this regard, Bohmian mechanics provides in a straightforward way the distribution of the time at which the particle actually does arrive at a given surface in 3-space in the absence of detectors. However, as we discuss here, since the presence of detectors can change the evolution of the wave function (...) and thus the particle trajectories, it cannot be taken for granted that the arrival time of the Bohmian trajectories in the absence of detectors agrees with the one in the presence of detectors, and even less with the detection time. In particular, we explain why certain distributions that Das and Dürr (Sci. Rep. 9: 2242, 2019) presented as the distribution of the detection time in a case with spin, based on assuming that all three times mentioned coincide, are actually not what Bohmian mechanics predicts. (shrink)

Quantum philosophy, a peculiar twentieth-century malady, is responsible for most of the conceptual muddle plaguing the foundations of quantum physics. When this philosophy is eschewed, one naturally arrives at Bohmian mechanics, which is what emerges from Schrodinger's equation for a nonrelativistic system of particles when we merely insist that 'particles' means particles. While distinctly non-Newtonian, Bohmian mechanics is a fully deterministic theory of particles in motion, a motion choreographed by the wave function. The quantum formalism emerges when measurement situations are (...) analyzed according to this theory. When the quantum formalism is regarded as arising in this way, the paradoxes and perplexities so often associated with quantum theory simply evaporate.Bohr's ... approach to atomic problems ... is really remarkable. He is completely convinced that any understanding in the usual sense of the word is impossible. Therefore the conversation is almost immediately driven into philosophical questions, and soon you no longer know whether you really take the position he is attacking, or whether you really must attack the position he is defending. (shrink)

"Wir mögen an der Natur beobachten, messen, rechnen, wägen und so weiter, wie wir wollen, es ist doch nur unser Maß und Gewicht, wie der Mensch das Maß der Dinge ist." So schrieb Goethe im Jahre 1807. "Die Natur wird uns keine Sonderbehandlung gewähren, nur weil wir uns als 'Krone der Schöpfung' betrachten... Ich fürchte, sie ist nicht eitel genug, um sich an den Menschen als einen Spiegel zu klammern, in dem allein sie ihre eigene Schönheit sehen kann", schreibt der (...) Physiker Hans-Peter Dürr heute. Diesen beiden Stellungnahmen liegen sehr unterschiedliche Vorstellungen vom Verhältnis Mensch - Natur zugrunde. Wie überhaupt die Naturphilosophie von den Vorsokratikern bis in die Gegenwart die unterschiedlichsten Varianten dieser Beziehung durchgespielt hat. Dass der Mensch sich jedoch in einem weit über die alttestamentarische Vorstellungskraft hinausgehenden Maße die Natur "untertan" gemacht und dabei großräumig zerstört hat, steht außer Zweifel. Im Rahmen der ökologischen Krise muss das Verhältnis zur Natur neu überdacht werden. Das vorliegende Lesebuch, das sich auch als Studientext und Diskussionsgrundlage für Schulen und Hochschulen bestens eignet, bietet den Blick in die Geschichte der Naturphilosophie, der dafür unerlässlich ist: Die Schwierigkeiten, die heute im Umgang mit der Natur auftreten, sind vielfach auf immer noch wirksame traditionelle Naturvorstellungen zurückzuführen. Andererseits gibt es einige eigenständige, bisher noch zu wenig berücksichtigte Ansätze, die zu neuen Konzeptionen anregen können. ------------------------------------------------------------- Inhalt: Vorwort; Einführung: Traditionslinien der Naturphilosophie; Heraklit und die Atomisten Leukipp und Demokrit; Platon und Aristoteles; Christliches Naturverstehen im Mittelalter: Aurelius Augustinus, Thomas von Aquin, Jacob Böhme; Naturvorstellungen in der beginnenden Neuzeit: Galileo Galilei, Rene Descartes, Isaac Newton; Kants Naturbegriff; Goethes Naturforschung; Nachkantische Naturphilosophie: Friedrich Wilhelm Joseph Schelling, Georg Wilhelm Friedrich Hegel; Geschichte der Natur und Kritik des Naturalismus: Karl Marx, Charles Darwin, John Stuart Mill; Kritik des Substanzbegriffes, Alfred North Whitehead, Werner Heisenberg, Ilya Prigogine und Isabelle Stengers; Bibliographie. (shrink)

Oft wird nur jenes anerkannt, was "wissenschaftlich beweisbar" ist. Ein solches Vorurteil vergisst, dass es auch andere Wirklichkeiten gibt. Ist unsere Welt ein Blick durch ein Kaleidoskop? Wie kann es sein, dass man eine mehr oder minder große Auswahl panoramenhafter Wirklichkeiten vor sich hat? Ist es möglich, solche Wirklichkeiten zu verlassen und in andere überzuwechseln? Anhand konkreter Beispiele wird dieser Wirklichkeits-Pluralismus beleuchtet. Das erste Beispiel, ein astronomisches, zeigt in aller Ausführlichkeit, auf welche Weise Wirklichkeit entstehen kann. Dann ist von anderen (...) naturwissenschaftlichen Wirklichkeiten die Rede, vom Licht und von der Farbe sowie von einer fremden heilkundlichen Wirklichkeit. Ein zentrales Anliegen von Gerhard Fasching ist ein Denken, welches in einen Wirklichkeitspluralismus mündet. Unser monokulturelles Wirklichkeitsverständnis hat nämlich schon viele Wirklichkeiten unserer eigenen Kultur und fremder Kulturen missachtet und dadurch verloren. Unser humanistisches Weltbild benötigt also ein breiteres Fundament. Das Buch findet zu einem überraschenden Ergebnis: Man selbst gehört nicht zur Wirklichkeit, sondern man steht stets außerhalb jeder Wirklichkeit. GERHARD FASCHING. Geb. 1933 in Wien, Univ.-Prof. Dipl.-Ing. Dr. techn., 1966 Habilitation, seit 1970 Ordinarius an der Technischen Universität Wien, Österreich. Er hält Vorlesungen über Aufbau und Eigenschaften der Materie und über Fragen der Erkenntnistheorie. HANS-PETER DÜRR. Em. Univ.-Prof., Direktor em. am Max-Planck-Institut für Physik, München, Deutschland. Träger des Alternativen Nobelpreises. (shrink)

"Wir mögen an der Natur beobachten, messen, rechnen, wägen und so weiter, wie wir wollen, es ist doch nur unser Maß und Gewicht, wie der Mensch das Maß der Dinge ist." So schrieb Goethe im Jahre 1807. "Die Natur wird uns keine Sonderbehandlung gewähren, nur weil wir uns als 'Krone der Schöpfung' betrachten... Ich fürchte, sie ist nicht eitel genug, um sich an den Menschen als einen Spiegel zu klammern, in dem allein sie ihre eigene Schönheit sehen kann", schreibt der (...) Physiker Hans-Peter Dürr heute. Diesen beiden Stellungnahmen liegen sehr unterschiedliche Vorstellungen vom Verhältnis Mensch - Natur zugrunde. Wie überhaupt die Naturphilosophie von den Vorsokratikern bis in die Gegenwart die unterschiedlichsten Varianten dieser Beziehung durchgespielt hat. Dass der Mensch sich jedoch in einem weit über die alttestamentarische Vorstellungskraft hinausgehenden Maße die Natur "untertan" gemacht und dabei großräumig zerstört hat, steht außer Zweifel. Im Rahmen der ökologischen Krise muss das Verhältnis zur Natur neu überdacht werden. Das vorliegende Lesebuch, das sich auch als Studientext und Diskussionsgrundlage für Schulen und Hochschulen bestens eignet, bietet den Blick in die Geschichte der Naturphilosophie, der dafür unerlässlich ist: Die Schwierigkeiten, die heute im Umgang mit der Natur auftreten, sind vielfach auf immer noch wirksame traditionelle Naturvorstellungen zurückzuführen. Andererseits gibt es einige eigenständige, bisher noch zu wenig berücksichtigte Ansätze, die zu neuen Konzeptionen anregen können. -/- ------------------------------------------------------------- Inhalt: Vorwort; Einführung: Traditionslinien der Naturphilosophie; Heraklit und die Atomisten Leukipp und Demokrit; Platon und Aristoteles; Christliches Naturverstehen im Mittelalter: Aurelius Augustinus, Thomas von Aquin, Jacob Böhme; Naturvorstellungen in der beginnenden Neuzeit: Galileo Galilei, Rene Descartes, Isaac Newton; Kants Naturbegriff; Goethes Naturforschung; Nachkantische Naturphilosophie: Friedrich Wilhelm Joseph Schelling, Georg Wilhelm Friedrich Hegel; Geschichte der Natur und Kritik des Naturalismus: Karl Marx, Charles Darwin, John Stuart Mill; Kritik des Substanzbegriffes, Alfred North Whitehead, Werner Heisenberg, Ilya Prigogine und Isabelle Stengers; Bibliographie. (shrink)

It is well known that density matrices can be used in quantum mechanics to represent the information available to an observer about either a system with a random wave function (“statistical mixture”) or a system that is entangled with another system (“reduced density matrix”). We point out another role, previously unnoticed in the literature, that a density matrix can play: it can be the “conditional density matrix,” conditional on the configuration of the environment. A precise definition can be given in (...) the context of Bohmian mechanics, whereas orthodox quantum mechanics is too vague to allow a sharp definition, except perhaps in special cases. In contrast to statistical and reduced density matrices, forming the conditional density matrix involves no averaging. In Bohmian mechanics with spin, the conditional density matrix replaces the notion of conditional wave function, as the object with the same dynamical significance as the wave function of a Bohmian system. (shrink)

Kaum ein anderer lebender Naturwissenschaftler besitzt die Fähigkeit, mit solcher Geistesklarheit die tiefsten Einsichten von moderner Quantenphysik mit dem uralten spirituellen Menschheitswissen zu verknüpfen wie - Hans-Peter Dürr! Es gelingt Dürr scheinbar mühelos, eine Synthese zwischen den meditativen Einsichten der Weisen des Ostens und den aktuellen Erkenntnissen der modernen Naturwissenschaften herzustellen. Dabei verliert er sich niemals in langatmigen akademischen Erläuterungen, sondern hat stets den Menschen und die gesellschaftliche Wirklichkeit des 21. Jahrhunderts im Blick. Ein Brückenschlag zwischen zwei Welten, der vielleicht (...) niemals notwendiger war als zurzeit. Eine kleines Meisterwerk, das in einleuchtender Weise aufzeigt - alles Leben ist EINS! (shrink)

We analyze the origin of quantum randomness within the framework of a completely deterministic theory of particle motion—Bohmian mechanics. We show that a universe governed by this mechanics evolves in such a way as to give rise to the appearance of randomness, with empirical distributions in agreement with the predictions of the quantum formalism. Crucial ingredients in our analysis are the concept of the effective wave function of a subsystem and that of a random system. The latter is a notion (...) of interest in its own right and is relevant to any discussion of the role of probability in a deterministic universe. (shrink)

Review of Teatro, escuela y masculinidades, by María Paz Gallardo Barría.

In classical physics, the world is considered as a matter-based reality, the arrangement of whose parts in time is uniquely determined by certain dynamic laws. By contrast, modern quantum physics reveals that matter is not composed of matter, but reality is merely potentiality. The world has a holistic structure, which is based on fundamental relations and not material objects, admitting more open, indeterministic developments. In this more flexible causal framework, inanimate and animate matter are not to be considered as fundamentally (...) different but as different order structures of the same immaterial entity. In a stable configuration, effectively all the uncertainties are statistically averaged out, thus the unique and deterministic behavior of ordinary inanimate matter is exhibited; whereas in the case of statically unstable but dynamically stable configurations, the “lively” features of the underlying quantum structure have a chance to surface to the mesocopic level and to be connected with what we observe as the phenomenon of life. This supposition can be more explicitly treated and clarified by identifying the electric dipole moment of biomolecules as the ordering parameter of the corresponding macroquantum system. This has important consequences for biology and medicine. In particular, it suggests the existence of a quantum-based “software,” essential perhaps for the logistics of biological processes, which are hidden behind the matter/energy-based “hardware” that alone is considered in the conventional approach. In medicine it opens an opportunity to build bridges between conventional medicine based essentially on the classical paradigm, and the various forms of complementary medicine, which have strong affinities with the new features of the modern holistic worldview. (shrink)

We submit that, contrary to the standard view, gravitational waves do not carry energy-momentum. Analysing the four standard arguments on which the standard view rests - viz. the kinetic effects of a GW on a detector, Feynman’s Sticky Bead Argument, an application of Noether’s Theorem and a general perturbative approach – we find none of them to be successful: Pre-relativistic premises underlie each of them – premises that, as we argue, no longer hold in General Relativity. Finally, we outline a (...) GR-consistent interpretation of the effects and, in particular, the spin-down of binary systems. (shrink)

We analyse the various conceptual notions that go under the umbrella “relationalism/substantivalism”. Our focus will be on evaluating the ontological status of spacetime in General Relativity. To this end we systematically develop the ontological framework that implicitly underlies the traditional debate and common understanding of physics. We submit that spacetime with its chronogeometric and inertial structure, represented by the triple of the bare manifold, the metric and the affine structure, is best construed as the totality of possible and actual spatiotemporal (...) relations of events. This can explain the non-fundamentality of general relativistic gravitational energy and suggests a non-causal, non-interactional understanding of the interdependence of matter in spacetime in GR. (shrink)

Bohmian Mechanics was formulated in 1952 by David Bohm as a complete theory of quantum phenomena based on a particle picture. It was promoted some decades later by John S. Bell, who, intrigued by the manifestly nonlocal structure of the theory, was led to his famous Bell's inequalities. Experimental tests of the inequalities verified that nature is indeed nonlocal. Bohmian mechanics has since then prospered as the straightforward completion of quantum mechanics. This book provides a systematic introduction to Bohmian mechanics (...) and to the mathematical abstractions of quantum mechanics, which range from the self-adjointness of the Schrödinger operator to scattering theory. It explains how the quantum formalism emerges when Boltzmann's ideas about statistical mechanics are applied to Bohmian mechanics. The book is self-contained, mathematically rigorous and an ideal starting point for a fundamental approach to quantum mechanics. It will appeal to students and newcomers to the field, as well as to established scientists seeking a clear exposition of the theory. (shrink)