Classical physics is about real objects, like apples falling from trees, whose motion is governed by Newtonian laws. In standard quantum mechanics only the wave function or the results of measurements exist, and to answer the question of how the classical world can be part of the quantum world is a rather formidable task. However, this is not the case for Bohmian mechanics, which, like classical mechanics, is a theory about real objects. In Bohmian terms, the problem of the classical (...) limit becomes very simple: when do the Bohmian trajectories look Newtonian? (shrink)

We criticize speculations to the effect that quantum mechanics is fundamentally about information. We do this by pointing out how unfounded such speculations in fact are. Our analysis focuses on the dubious claims of this kind recently made by Anton Zeilinger.

Book to honor the work of GianCarlo Ghirardi.

The present paper revisits the debate between realists about gravitational energy in GR and anti-realists/eliminativists. I re-assess the arguments underpinning Hoefer’s seminal eliminativist stance, and those of their realist detractors’ responses. A more circumspect reading of the former is proffered that discloses where the so far not fully appreciated, real challenges lie for realism about gravitational energy. I subsequently turn to Lam and Read’s recent proposals for such a realism. Their arguments are critically examined. Special attention is devoted to the (...) adequacy of Read’s appeals to functionalism, imported from the philosophy of mind. (shrink)

This chapter contains sections titled: Nothing Wants to Die An Eye for an Eye, a Tooth for a Tooth Solution 1: Keep Your Powder Dry Solution 2: Pretend It Wasn't You Solution 3: Give, and Ye Shall Receive Solution 4: Take Only What You Need Solution 5: Cheat Death The Keepers of the Game as a Moral Authority Notes.

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)

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)

Galt Xenokrates in der bisherigen Forschung nur als subalterner Dogmatiker, so wirft diese Arbeit ein neues Licht auf den dritten Akademieleiter. Die Gesamtdarstellung seiner Philosophie enthält neben der Kosmologie, Theologie und Ontologie erstmalig auch seine Prinzipienlehre. Diese findet sich im berühmten Sextus-Bericht, Adv. Math., X §§ 248-283, der auf der Folie der Philosophie des Xenokrates neu gelesen wird. Die darin vorgestellte monistische Prinzipienlehre stammt von Xenokrates, der in seine Berichterstattung über Platons Ungeschriebene Lehre seine eigenen Lehrsätze mit einfließen ließ. Diese (...) Prinzipienlehre stellt das Bindeglied zwischen der Seinsmetaphysik des Aristoteles und der Einheitsmetaphysik Platons dar, da das erste Prinzip, die absolute Monas, nushaft und seinstranszendent ist. Xenokrates erweist sich als platontreuer und innovativer Denker, als 'Fels', auf den Platon seine Lehre und seine Schule gründen konnte. (shrink)

Dr. theol. Dr. phil. Detlef Schwartz, Jahrgang 1954, Pfarrer i. R. und langjähriger nebenamtlicher Universitätsdozent, mit Stationen in Deutschland und den USA sowie Lateinamerika, zieht eine vorläufige Bilanz seiner bisherigen Arbeit im Auslandsdienst der Evangelischen Kirche in Deutschland. Er ordnet diese ein in Erfahrungen in einem Pfarramt der United Church of Christ, USA, und seinen Beobachtungen in der Millionenmetropole Los Angeles. Die Konsequenz eines verstärkten Dialogs der Religionen, besonders mit dem Islam, koppelt er zurück an die Frage nach der (...) Notwendigkeit eines Paradigmenwechsels im Religionsunterricht hin zu einem den Dialog fördernden Kulturunterrichts."-- Back cover. (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)

Bohmian mechanics is a theory about point particles moving along trajectories. It has the property that in a world governed by Bohmian mechanics, observers see the same statistics for experimental results as predicted by quantum mechanics. Bohmian mechanics thus provides an explanation of quantum mechanics. Moreover, the Bohmian trajectories are defined in a non-conspiratorial way by a few simple laws.

The paper takes up Bell's “Everett theory” and develops it further. The resulting theory is about the system of all particles in the universe, each located in ordinary, 3-dimensional space. This many-particle system as a whole performs random jumps through 3N-dimensional configuration space – hence “Tychistic Bohmian Mechanics”. The distribution of its spontaneous localisations in configuration space is given by the Born Rule probability measure for the universal wavefunction. Contra Bell, the theory is argued to satisfy the minimal desiderata for (...) a Bohmian theory within the Primitive Ontology framework. TBM's formalism is that of ordinary Bohmian Mechanics, without the postulate of continuous particle trajectories and their deterministic dynamics. This “rump formalism” receives, however, a different interpretation. We defend TBM as an empirically adequate and coherent quantum theory. Objections voiced by Bell and Maudlin are rebutted. The “for all practical purposes”-classical, Everettian worlds exist sequentially in TBM. In a temporally coarse-grained sense, they quasi-persist. By contrast, the individual particles themselves cease to persist. (shrink)

In the following paper, I review and critically assess the four standard routes commonly taken to establish that gravitational waves possess energy-momentum: the increase in kinetic energy a GW confers on a ring of test particles, Bondi/Feynman’s Sticky Bead Argument of a GW heating up a detector, nonlinearities within perturbation theory, taken to reflect the fact that gravity contributes to its own source, and the Noether Theorems, linking symmetries and conserved quantities. Each argument is found to either to presuppose controversial (...) assumptions or to be outright spurious. I finally examine the standard interpretation of binary systems, according to which orbital decay is explained in terms of the system’s energy being via GW energy- momentum transport. I contend that a better interpretation, drawing only on the general-relativistic Equations of Motions and the Einstein Equations, is available - and in fact preferable; thereby also an inference to the best explanation for the vindication of GW energy-momentum is blocked. (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)

This article revisits Karl Popper’s falsificationist methodology with respect to three tasks. The first is to illuminate and systematize Popper’s methodological views in light of his core epistemological commitments. A second and related objective is to gauge which aspects of falsificationism should be identified as “conventionalist”—a label that Popper himself uses (albeit with qualifications) but that is compromised by and, thus, stands in need of elucidation because of Popper’s idiosyncratic understanding of conventionalism. Third, by elaborating Popper’s virtue-epistemological, dialogical model of (...) rationality, I show how Popper’s conventionalism, fallibilism, and critical rationalism form a coherent system. This system allows Popper to accord science the status of a privileged source of knowledge—without naïve appeal to authority. My systematization of Popper’s views yields an intrinsically and exegetically more satisfactory reading of Popper’s falsificationism than usual presentations. Thanks to its marked flexibility and methodological liberalism, it bypasses many standard objections but still offers sound and relevant methodological advice. With its “virtue-methodological” thrust, Popper sketches an original and promising approach to methodology, the fertility of which deserves further exploration for contemporary debates. (shrink)

What constitutes a scientific discovery? What role do discoveries play in science, its dynamics and social practices? Must every discovery be attributed to an individual discoverer (or a small number of discoverers)? The paper explores these questions by first critically examining extant philosophical explications of scientific discovery—the models of scientific discovery, propounded by Kuhn, McArthur, Hudson, and Schindler. As a simple, natural and powerful alternative, we proffer the “change-driver model”: in a nutshell, it takes discoveries to be cognitive scientific results (...) that have epistemically advanced science. The model overcomes the shortcomings of its precursors, whilst preserving their insights. We demonstrate its intensional and extensional superiority, especially with respect to the link between scientific discoveries and the dynamics of science, as well as the award system of science. Both as an illustration, and as an application to a recent scientific and political controversy, we apply the considered models of discovery to one of the most momentous discoveries of science: the expansion of the universe. We oppose the 2018 proposal of the International Astronomers’ Union as too simplistic vis-`a-vis the historical complexity of the episode. The change- driver model yields a more nuanced and circumspect verdict: (i) The redshift-distance relation shouldn’t be named the “Hubble-Lemaître Law”, but “Slipher-Lundmark-Hubble-Humason Law”; (ii) Its interpretation in terms of an expanding universe, however, Lemaître ought to be given credit for; but (iii) The establishment of the expansion of the universe, as an evidentially sufficiently warranted result, is a communal achievement, emerging in the 1950s or 1960s. (shrink)

Das Wirken Gabriel Biels, eines der bedeutendsten Theologen des Spatmittelalters, ist nicht nur durch scharfsinniges, vor allem an Ockham, aber auch an Scotus orientiertes theologisches Nachdenken gekennzeichnet. Es ist ebenso gepragt durch die Devotio moderna. Aus dieser Quelle speist sich sein unermuedlicher Einsatz fuer eine Kirchenreform wie auch seine tiefe Frommigkeit. Trotz Kenntnis der Bedeutung dieser Linie fuer Biels Frommigkeitspraxis blieb sein Verhaltnis zur Mystik bisher unerforscht. Das vorliegende Buch fuellt diese Luecke. Es sammelt aus Biels Hauptwerken, dem Collectorium und (...) der Auslegung des Meakanons, die mystischen Elemente (wie z.B. raptus, Einwohnung, unio, transformatio) und analysiert deren Rezeption. Dabei beruecksichtigt es auch das Vorfeld von Mystik in Gebet und Meditation. Einen anderen Schwerpunkt bildet Biels Stellung zum Phanomen religioser und mystischer Erfahrung. Einen qualifizierten Begriff religioser Erfahrung entwickelt Biel nicht. Er wertet sie durchaus positiv, doch gilt ihm als das Hochste im Christenleben die Liebe. Betrachtet man aber die Funktion der Mystik in Biels Werken, so ist seine Theologie im weiteren Sinne mystagogisch. In devoter Tradition stehend, will er zur Frommigkeit hinfuehren. Nicht zu hoch veranschlagt werden darf die Relevanz des Nominalismus fuer Biels Mystik-Rezeption. Mit Register. "Es ist M. gelungen, in seiner grundgelehrten Untersuchung einmal die Forschung der Theologie Biels erheblich weiter voranzutreiben, und er hat zugleich zu uebergeordneten Fragen substantielle Beitrage geleistet." Theologische Rundschau "a ein solider und fuer die Erforschung der spatmittelalterlichen Theologie und Frommigkeit unentbehrlicher Beitraga" Rottenburger Jahrbuch fuer Kirchengeschichte "Durch sorgfaltige Analysen diesen verkannten theologischen Denker in die Gegenwart geholt zu haben - dies ist ein Verdienst dieser Arbeit." Hulda "Die beeindruckenden Starken der Arbeit liegen in der behutsamen, differenzierten Einzelanalyse" Theologische Literaturzeitung. (shrink)