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)

(a historical text with comments - 11pages pdf - 80kB).

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

Time travel is one of mankind's most ancient dreams. It inspires our imagination and provides material for bizarre stories. H. G. Wells' novel, "The Time Machine" (1895), marks the beginning of a long history of science fiction literature devoted to the subject of time travel. -/- A work on the subject of time travel forces us to re-examine our concept of "time". The complexity and the contradictory nature this subject makes it difficult to be more precise about "time". On its (...) deepest subjective side, time is a means of perception, a biological rhythm, a social phenomenon in terms of our collective understanding of time. But it is also a physical parameter. -/- Einstein's Theory of Relativity revolutionised our idea of space and time by freeing us from the Newtonian concept of absolute space and absolute time. The "problem of time travel", a subject that Wells wrote about just ten years before as mere fiction, was now a discussion worthy of physics. Einstein's Special Theory of Relativity (1905), by predicting the effects of time dilation, allowed for "travels into the future" and Einstein's Theory of Gravity used closed time-like lines for solutions to calculations about time travel (for example, the Gödel Universe and the Anti-de Sitter Universe). However, a trip to a time warp would immediately involve a whole set of paradoxes (for example, the grandfather paradox and the information paradox) and semantic inconsistencies. -/- This work discusses approaches for "time machines" which are consistent with modern physics. Some of the discussions that will be presented are the tachyon hypothesis, Tipler's rotating cylinder, the Gödel Universe, the Anti-de Sitter Universe and so-called "wormholes". At the same time, approaches will be presented (for example, Eternalism, the Many-Worlds Interpretation and the Consistent Histories Approach) that will provide attempts to find a solution for paradoxes regarding time travel to the past. -/- Surprisingly, the fundamental laws of physics (apart from extremely rare and non-emergent macroscopic quantum mechanical effects) are not violated by the concept of time reversal. Yet, in nature, there still seems to be a fundamental prohibition against time travel to the past. Physicist Dieter Zeh, whose position is more closely presented in the final chapter of this work, supports the view that science fiction literature on the subject of "time travel" is overwhelmingly based on simple conceptual errors. The processes used in this literature, which are based on the General Theory of Relativity, at best, are just as "theoretically possible" as a gas which gathers itself into the corner of a container. -/- Questions about time travel to the past are like the questions asked on Radio Yerevan. The answer is always, "In principle yes, but…" But the fascination about time travel will continue to provide material for "fiction". // -/- Zeitreisen sind ein alter Menschheitstraum; sie beflügeln die Fantasie und bieten Stoff für skurrile Geschichten. Wells’ Roman „Die Zeitmaschine (1895)“ steht am Anfang einer Fülle von Science-Fiction-Literatur, die sich dem Thema der Zeitreisen widmet. -/- Eine Arbeit zum Thema Zeitreisen zwingt zu einer Auseinandersetzung mit dem Begriff der „Zeit“. Die Vielschichtigkeit und der antinomische Charakter dieses Begriffes machen es schwer, „Zeit“ genauer zu fassen. Zeit tritt uns entgegen als Form der Wahrnehmung in ihrer zutiefst subjektiven Seite, als biologischer Rhythmus, als soziales Phänomen im Sinne einer kollektiven Zeitbestimmung, aber eben auch als physikalischer Parameter. -/- Einsteins Relativitätstheorie revolutioniert unsere Vorstellungen von Raum und Zeit, indem sie sich vom newtonsch-mechanischen Konzept des absoluten Raumes und der absoluten Zeit löst. Sie macht aber das, was bei Wells zehn Jahre vorher noch reine Fiktion war, zu einem für die Physik diskussionswürdigen Thema, nämlich das „Problem der Zeitreisen“. Einsteins Spezielle Relativitätstheorie (1905) erlaubt durch den von ihr vorhergesagten Effekt der Zeitdilatation „Reisen in die Zukunft“ und die Einsteinsche Gravitationstheorie lässt geschlossene zeitartige Linien als Lösungen ihrer Gleichungen zu (z. B. Gödel-Kosmos, Anti-de-Sitter-Kosmos). Allerdings würde eine Reise auf einer Zeitschleife sofort ein ganzes Bündel von Paradoxien (z.B. Großvater-Paradoxon, Informationsparadoxon) und semantischen Inkonsistenzen nach sich ziehen. -/- Die vorliegende Arbeit erörtert Ansätze für „Zeitmaschinen“, die in Einklang mit der modernen Physik stehen. Besprochen werden u. a. die Tachyonen-Hypothese, Tiplers rotierender Zylinder, der Gödel-Kosmos, der Anti-de-Sitter-Kosmos und die sogenannten „Wurmlöcher“. Zugleich sollen Ansätze vorgestellt werden (z. B. Eternalismus, Viele-Welten-Modell, Prinzip der konsistenten Geschichte), die Lösungsversuche für die Paradoxien von Vergangenheitsreisen bieten. -/- Obwohl erstaunlicherweise die fundamentalen Gesetze der Physik (abgesehen von extrem seltenen und makroskopisch nicht in Erscheinung tretenden quantenmechanischen Effekten) bei einer Zeitumkehr nicht verletzt sind, scheint es in der Natur doch ein grundsätzliches Verbot von Vergangenheitsreisen zu geben. Der Physiker Dieter Zeh, dessen Position im Schlusskapitel der Arbeit näher beleuchtet wird, vertritt die Auffassung, dass die Science-Fiction-Literatur zum Thema „Zeitreisen“ überwiegend auf einfachen begrifflichen Fehlern beruhe. Die in Anlehnung an die Allgemeine Relativitätstheorie konstruierten Vorgänge seien bestenfalls genauso „theoretisch möglich“ wie ein Gas, das sich von selbst in einer Ecke des Gefäßes versammelt. -/- Um die Reisen in die Vergangenheit scheint es zu stehen wie mit einer Anfrage an Radio Jerewan; die Antwort lautet stets: „Im Prinzip ja, aber …“ Doch die Faszination dieser Idee wird weiterhin Stoff für die „Fiction“ liefern. (shrink)

I criticize two accounts of the temporal asymmetry of electromagnetic radiation - that of Huw Price, whose account centrally involves a reinterpretation of Wheeler and Feynman's infinite absorber theory, and that of Dieter Zeh. I then offer some reasons for thinking that the purported puzzle of the arrow of radiation does not present a genuine puzzle in need of a solution.

These two books, both by distinguished authors, are excellent. Though they are written by and for physicists, they are an invaluable resource for philosophers interested in the grand theme of how classical physical phenomena emerge from the quantum realm. Both individually and taken together, they are fine representatives of the present state of knowledge about this theme, and about many more specific topics falling under it. They are also pedagogic, though aimed at an advanced level—graduate students and beyond, in physics (...) and mathematics. Thus, they are packed with sophisticated expositions of such topics as quantum Brownian motion, and decoherence in quantum field theory, the rigorous definition of macroscopic observables and of their evolution laws in quantum statistical physics, and the rigorous treatment of open quantum systems. So overall, they provide an invaluable overview of a large and lively research area of physics. But the books are also different in several ways. The first book, by Joos et al., has six authors, all theoretical physicists based in Germany and part of the ‘Heidelberg school’ of decoherence physics, which has grown up in the last twenty-five years under the tutelage of Heinz- Dieter Zeh. The second book is a monograph: Sewell is a British mathematical physicist, most of whose work has been in the algebraic approach to quantum statistical mechanics. Other, less obvious, differences follow on from these. By and large, the material in Decoherence is both more familiar and more accessible to philosophers of physics. And for reviewing the books for philosophers of physics, it will be a convenient strategy to spell out the three reasons for this contrast. But as we shall see, Quantum Mechanics being more difficult need not mean it is less valuable. First, decoherence processes of the kinds that Joos, et al., mostly discuss are now well-known to philosophers of quantum theory, not least through the work of the Heidelberg school itself and of the ‘Los Alamos school’ of Zurek and coauthors. Indeed, Joos’ own Chapter 3, “Decoherence through Interaction with the... (shrink)

Time travel and superluminal travel are two of mankind's dreams. They inspire our imagination and provide material for bizarre stories. -/- A work on the subject of time travel and superluminal travel forces us to re-examine our concept of "time". The complexity and the contradictory nature this subject makes it difficult to be more precise about "time". On its deepest subjective side, time is a means of perception, a biological rhythm, a social phenomenon in terms of our collective understanding of (...) time. But it is also a physical parameter. -/- Albert Einstein's Theory of Relativity revolutionised our idea of space and time by freeing us from the Newtonian concept of absolute space and absolute time. The "problem of time travel", a subject that Herbert George Wells wrote about just ten years before as mere fiction, was now a discussion worthy of physics. Albert Einstein's Special Theory of Relativity (1905), by predicting the effects of time dilation, allowed for "travels into the future" and Albert Einstein's Theory of Gravity used closed time-like lines for solutions to calculations about time travel (for example, the Gödel Universe and the Anti-de Sitter Universe). However, a trip to a time warp would immediately involve a whole set of paradoxes (for example, the grandfather paradox and the information paradox) and semantic inconsistencies. -/- Surprisingly, the fundamental laws of physics (apart from extremely rare and non-emergent macroscopic quantum mechanical effects) are not violated by the concept of time reversal. Yet, in nature, there still seems to be a fundamental prohibition against time travel to the past. Physicist Dieter Zeh, whose position is more closely presented in the final chapter of this work, supports the view that science fiction literature on the subject of "time travel" is overwhelmingly based on simple conceptual errors. The processes used in this literature, which are based on the General Theory of Relativity, at best, are just as "theoretically possible" as a gas which gathers itself into the corner of a container. -/- This work discusses approaches for "time machines" and superluminal travel which are consistent with modern physics. Some of the discussions that will be presented are the tachyon hypothesis, Frank J. Tipler's rotating cylinder, the Gödel Universe, the Anti-de Sitter Universe, so-called "wormholes" and the Alcubierre-metric. At the same time, approaches will be presented (for example, Eternalism, the Many-Worlds Interpretation and the Consistent Histories Approach) that will provide attempts to find a solution for paradoxes regarding time travel to the past. -/- Questions about time travel to the past and superluminal travel are like the questions asked on Radio Yerevan. The answer is always, "In principle yes, but…" But the fascination about time travel will continue to provide material for "fiction". (shrink)

It is demonstrated that neither the arguments leading to inconsistencies in the description of quantum-mechanical measurement nor those “explaining” the process of measurement by means of thermodynamical statistics are valid. Instead, it is argued that the probability interpretation is compatible with an objective interpretation of the wave function.

The program of a physical concept of information is outlined in the framework of quantum theory. A proposal is made for how to avoid the intuitive introduction of observables. The conventional and the Everett interpretations in principle may lead to different dynamical consequences. An ensemble description occurs without the introduction of an abstract concept of information.

The relation between quantum measurement and thermodynamically irreversible processes is investigated. The reduction of the state vector is fundamentally asymmetric in time and shows an observer-relatedness which may explain the double interpretation of the state vector as a representation of physical states as well as ofinformation about physical states. The concept of relevance being used in all statistical theories of irreversible thermodynamics is demonstrated to be based on the same observer-relatedness. Quantum theories of irreversible processes implicitly use an objectivized process (...) of state vector reduction. The conditions for the reduction are discussed, and it is concluded that the final (subjective) observer system may be carried by a space point. (shrink)

The interpretations of measurements in Bohm's and Everett's quantum theories are compared. Since both theories are based on the assumption of a universally valid Schrödinger equation, they face the common problem of how to explain that arrow of time, which in conventional quantum theory is represented by the collapse of the wave function. Its solution requires, in a statistical sense, a very improbable initial condition for thetotal wave function of the universe. The historical importance of Bohm's quantum theory is pointed (...) out. (shrink)

It is argued by means of analogy with certain irreversible processes that a symmetry-violating vacuum need not necessarily be explained by a special cosmic initial condition.

Dieter Birnbacher is professor of philosophy at the University of Düsseldorf and a member of the Foundation for the Rights of Future Generations’ scientific board. In 1988 he published the book Verantwortung für zukünftige Generationen ; which was translated into French and Polish. Hanna Schudy is an ethicist and environmentalist interested in questions of intergenerational responsibility concerning the natural environment. She is a doctoral student at the University of Wroclaw and a DAAD scholarship holder. The interview was conducted in (...) December 2011 at the Heinrich Heine Universität; Duesseldorf. It is part of Ms. Schudy’s current research into “The principle of responsibility in Hans Jonas’ and Dieter Birnbacher’s environmental ethics”. (shrink)

Anderswo im Anderswann–Autofiktion als Utopie21.–23.03.2018 im Tagungshotel Schloss Gnadenthal, KleveDr. Yvonne Delhey, Prof. Dr. Rolf Parr und Dr. Kerstin Wilhelms Ihre Gemeinsamkeiten offenbaren die Konzepte der Utopie und der Autofiktion erst auf einenzweiten Blick. Die Utopie beschreibt–zumindest im alltagssprachlichen Verständnis–einenin die Zukunft projizierten gesellschaftlichen Gegenentwurf. Die Utopie [gr. oὐ und τóπoς,‚nicht', ‚Ort'] ist der Nicht-Ort, ein fi ktionales Produkt. Die Autofiktion wiederum hat ihrenUrsprung zwar in der Autobiographieforschung, adressiert im Gegensatz zur an Authentizitätund...

The article reports considerable changes in the content and style of German election coverage between 1990 and 2002. The findings are based on a content analysis of the main evening news of the four major television channels, spanning four Bundestag elections. During the observation period, television has immensely expanded its coverage of the top candidates. While the presence of the candidates in the news increased, they were not able to get their issues across to the audience. The news discourse was (...) narrowed down to election and campaigning as issues. Matters of campaigning style, the ‘game schema’, as well as election polls became increasingly salient. The number of sound bites grew, although the average sound bite length decreased slightly. The presentation of the candidates became more vivid and more colorful, and, thus, more attractive for the audience. On the other hand, there are no signs of increasing negativism. The observable trends in the scope and kind of presentation of candidates can be interpreted as increasing personalization and dramatization of media coverage. The changes partially fit into the pattern of convergence. These developments are partly rooted in the change of the German television market. Other results can be explained by historical incidents such as the German unification in 1990, and by the candidate constellation during each election. In spite of some similarities with developments in the US, the authors argue that it would be misleading to label the observable changes of German election coverage as ‘Americanization’. (shrink)

Thanks to the editorial work of David Pacini, the lectures appear here with annotations linking them to editions of the masterworks of German philosophy as they ...

Hence, there is still controversy over which of the two versions of the deduction deserves priority and whether indeed any distinction between them can be maintained that would go beyond questions of presentation and involve the structure of the proof itself. Schopenhauer and Heidegger held that the first edition alone fully expresses Kant's unique philosophy, while Kant himself, as well as many other Kantians, have only seen a difference in the method of presentation.

The relation between ethics and social science is often conceived as complementary, both disciplines cooperating in the solution of concrete moral problems. Against this, the paper argues that not only applied ethics but even certain parts of general ethics have to incorporate sociological and psychological data and theories from the start. Applied ethics depends on social science in order to asses the impact of its own principles on the concrete realities which these principles are to regulate as well as in (...) order to propose practice rules suited to adapt these principles to their respective contexts of application. Examples from medical ethics (embryo research) and ecological ethics (Leopold's land ethic) illustrate both the contingence of practice rules in relation to their underlying basic principles and the corresponding need for a co-operation between philosophy and empirical disciplines in judging their functional merits and demerits. In conclusion, the relevance of empirical hypotheses even for some of the perennial problems of ethics is shown by clarifying the role played by empirical theories in the controversies about the ethical differentiation between positive and negative responsibility and the relation between utility maximisation and (seemingly) independent criteria of distributive justice in the context of social distributions. (shrink)

This is a collection of four essays on aesthetic, ethical, and political issues by the pre-eminent Kant scholar in Germany today, perhaps best known for rekindling interest in the great classical German tradition from Kant to Fichte.

The scope of my considerations here is defined along two lines, which seem to me of essential relevance for a theory of dialectic. On the one hand, the form of negation that – as self-referring antinomical negation – gains a quasi-semantic expulsory force [Sprengkraft] and therewith a forwarding [weiterverweisenden] character; on the other hand, the notion that every logical category is defective insofar as the explicit meaning of a category does not express everything that is already implicitly presupposed for its (...) meaning. Both lines are tightly interwoven. This I would like to demonstrate with the example of the dialectic of Being and Non-Being at the beginning of the Hegelian Logic. I will first make visible the basic structures of dialectical argumentation (sections II and III) – whereby certain revisions will turn out to be necessary in comparison with Hegel’s actual argument. Thereby it proves essential that the whole apparatus of logical categories and principles must be always already available and utilized for the dialectical explication: proving dialectic as a self-explication of logic by logical means: dialectic, as it were, as the self-fulfillment of logic (sections IV–VI). (shrink)

In this collection comprising four of his most influential essays, Henrich proves himself unique in the conjunction of philosophical acumen, insight, and originality that he brings to Kant interpretation.