The Einstein–Podolsky–Rosen paradox (1935) is reexamined in the light of Shannon’s information theory (1984). The EPR argument did not take into account that the observer’s information was localized, like any other physical object.

Bell inequalities are derived for any number of observers, any number of alternative setups for each one of them and any number of distinct outcomes for each experiment. It is shown that if a physical system consists of several distant subsystems, and if the results of tests performed on the latter are determined by local variables with objective values, then the joint probabilities for triggering any given set of distant detectors are convex combinations of a finite number of Boolean arrays, (...) whose components are either 0 or 1 according to a simple rule. This convexity property is both necessary and sufficient for the existence of local objective variables. It leads to a simple graphical method which produces a large number of generalized Clauser-Horne inequalities corresponding to the faces of a convex polytope. It is plausible that quantum systems whose density matrix has a positive partial transposition satisfy all these inequalities, and therefore are compatible with local objective variables, even if their quantum properties are essentially non-local. (shrink)

Popper conceived an experiment whose analysis led to a result that he deemed absurd. Popper wrote that his reasoning was based on the Copenhagen interpretation and therefore invalidated it. Many authors who have examined Popper's analysis have found in it various technical flaws which are briefly summarized here. However, the aim of the present article is not technical. My concern is to redress logical flaws in Popper's argument: the terminology he uses is ambiguous, his analysis involves counterfactual hypotheses, and it (...) violates Bohr's complementarity principle. Therefore, the absurdity of Popper's result only confirms Bohr's approach. (shrink)

The proof of Bell's inequality is based on the assumption that distant observers can freely and independently choose their experiments. As Bell's inequality isexperimentally violated, it appears that distant physical systems may behave as a single, nonlocal, indivisible entity. This apparent contradiction is resolved. It is shown that the “free will” assumption is, under usual circumstances, an excellent approximation.I have set before you life and death, blessing and cursing: therefore choose life.... —Deuteronomy XXX, 19.

This paper contains four new dialogues among Simplicio, Salviati, and Sagredo, on the fate of Schrödinger's cat, the existence of physical quantities, the paradigm of Einstein, Podolsky, and Rosen, and why a watched kettle may boil, after all.

Linear combinations of “elements of reality,” as defined by Einstein, Podolsky, and Rosen, may not be themselves “elements of reality.” There are questions which can be formulated (and unambiguously answered) in the ordinary language of experimental physics, but cannot be represented in the mathematical framework of quantum theory in a nontrivial way.

The purpose of this paper is to review and clarify the quantum “measurement problem.” The latter originates in the ambivalent nature of the “observer”: Although the observer is not described by the Schrödinger equation, it should nevertheless be possible to “quantize” him and include him in the wave function if quantum theory is universally valid. The problem is to prove that no contradiction may arise in these two conflicting descriptions. The proof invokes the notion of irreversibility. The validity of the (...) latter is questionable, because the standard rationale for classical irreversibility, namely mixing and coarse graining, does not apply to quantum theory. There is no chaos in a closed, finite quantum system. However, when a system is large enough, it cannot be perfectly isolated from its “environment,” namely from external (or even internal) degrees of freedom which are not fully accounted for in the Hamiltonian of that system. As a consequence, the long-range evolution of such a quantum system is essentially unpredictable. It follows that the notion of irreversibility is a valid one in quantum theory and the “measurement problem” can be brought to a satisfactory solution. (shrink)

An imprecise measurement of a dynamical variable (such as a spin component) does not, in general, give the value of another dynamical variable (such as a spin component along a slightly different direction). The result of the measurement cannot be interpreted as the value of any observable that has a classical analogue.

A generalized Kochen-Specker theorem is proved. It is shown that there exist sets of n projection operators, representing n yes-no questions about a quantum system, such that none of the 2″ possible answers is compatible with sum rules imposed by quantum mechanics. Namely, if a subset of commuting projection operators sums up to a matrix having only even or only odd eigenvalues, the number of “yes” answers ought to he even or odd, respectively. This requirement may lead to contradictions. An (...) example is provided, involving nine projection operators in a 4-dimensional space. (shrink)

The physicist not only observes phenomena, but he also has an active role in the formulation of some laws. For instance, laws involving irreversibility refer explicitly to what can or cannot be done by physicists. As the abilities of the latter may vary, we obtain sequences of laws, the convergence of which is discussed.

The city of lions. Beaulieu-sur-Dordogne. The war starts. Drôle de guerre. Going to work. Going to school. Fleeing from village to village. Playing cat and mouse. The second landing. Return to Beaulieu. Return to Paris. Joining the boyscouts. Learning languages. Israel becomes independent. Arrival in Haifa. Kalay high school. Military training. The Hebrew Technion in Haifa. Relativity. Asher Peres. Metallurgy. Return to France. Escape from jail. Aviva.I am the cat who walks by himself, and all places are alike (...) to me.Rudyard KiplingI am grateful to all those who contributed to this Festschrift which celebrates my 70th birthday and therefore the beginning of my eighth decade. In the Jewish religion, there is a prayer, “she-hehhyanu” to thank the Lord for having kept us alive and let us reach this day. I am an atheist and I have no Lord to thank, but I wish to thank many other people who are no longer alive and who helped me reach this point. (shrink)

A pair of spin-j particles, prepared in a singlet state, move away from each other and are examined by two distant observers. If the latter are able to discriminate between the2j+1 values of a component ofJ, there are pairs of observables whose correlation strongly violates Bell's inequality, for arbitrarily large j. However, if neighboring values are lumped together because of limited instrumental resolution, the observable correlations tend to those predicted by classical mechanics.

The most efficient way of obtaining information about the state of a quantum system is not always a direct measurement. It is sometimes preferable to extend the original Hilbert space of states into a larger space, and then to perform a quantum measurement in the enlarged space. Such an extension is always possible, by virtue of Neumark's theorem. The physical interpretation usually given to that theorem is the introduction of an auxiliary quantum system, prepared in a standard state, and the (...) execution of a quantum measurement on both systems together. However, this widespread interpretation is unacceptable, because the statistical properties of the supposedly standard auxiliary system are inseparably entangled with those of the original, unknown system. A different method of preparing the auxiliary system is proposed, and shown to be physically acceptable. (shrink)

“Elements of reality” are defined as in the work of Einstein, Podolsky, and Rosen. It is further assumed that the sum or product of twocommuting elements of reality also is an element of reality. An algebra contradiction ensues.

Preface for Festschrift for Asher Peres's 70th Birthday, Foundations of Physics, issues 35(11), 35(12), and 36(1). -/- “All my friends!” These were nearly the first words I ever heard come from Asher Peres’s mouth. It was at a conference in Maryland in 1994 honoring the 83rd birthday of John Wheeler. The first morning of the meeting I spied Asher walk out of the lecture hall and into a long hallway where, in the distance, he saw (...) a group of old colleagues. His words came out so spontaneously and so lovingly it left a mark on me. I thought, “What a wonderful way to lead a life!—to have results that effect the world over, to travel the world reporting them, to see each conference as a family reunion.” Asher was a man of family—his blood family in Israel and his family of physicist colleagues throughout the world. He nurtured all of us, and we are what we are in large part because of him. (shrink)

This study is primarily a call to philosophers to attend the concerns raised by the increasing possibility of indefinitely extended human life. While these concerns are largely moral and socio-political, questions arising from this possibility are seen to involve other philosophical areas, including epistemology.Starting with the age-old desire for extended, enjoyable life, possible strategies for realizing such life are considered. Such realization is shown to conflict with the desire for children. Various reasons for choice between the alternatives of indefinitely extended (...) life and what is currently understood to be a normal life, including the possibility of offspring, are examined. Competing social visions are sketched for the purpose of resolving this dilemma. It is argued that humanity’s likely choice from among the competing social sketches favors the decision for extended life against that for limited lifespan with the possibility of children. Assuming that the extended life will be a life of learning leads to epistemological considerations regarding what is to be learned. (shrink)

RésuméJohn Searlea récemment soutenu que le cerveau ne peut pas être un ordinateur (non connexionniste). Son argument est que les vrais systèmes physiques comme les cerveaux fonctionnent à la causalité, tandis que les opérations computationnelles ne sont pas causales, mais sont plutôt des séquences formelles qui requièrent un interprète extérieur pour lew existence en tant que systèmes formels. Les vrais systèmes physiques, par contre, ne requièrent aucune interprétation pour lew existence comme systèmes physiques opérationnels.Contrairement à Searle, je soutiens qu'iln'y a (...) pas de démarcation nette entre notre application des formalismes mathématiques standard à des phénomènes physiques comme les oscillations, et notre application des formalismes computationnels aux divers phénomènes physiques qui sont, effectivement ou potentiellement, bien décrits et expliqués pas ces formalismes. (shrink)

Martin Buber’s political thought has enjoyed renewed attention lately, particularly his concept of “theopolitics,” a type of political practice that recognizes God as the ultimate political authority. In Buber’s biblical exegesis, theopolitics is a condition of everyday life in premonarchical Israel, but following the installation of the monarchy, it becomes a specialized activity of prophets, consisting chiefly in divinely commanded intercession against state actions. Buber suggests that a version of this prophetic activity is manifest in present-day socialist cooperatives, especially the (...) kibbutzim. Indeed, for Buber, these cooperatives can be seen as laying the groundwork for messianic redemption. This essay probes some potentially troubling implications of Buber’s theopolitical framework, taking objections raised in Walter Benjamin’s correspondence as an entry point. A central concern for Benjamin is Buber’s nationalist articulation of Jewish identity, which appears all the more problematic when considered in tandem with the teleological view of history evident in Buber’s framework. (shrink)

The study of the feeling of knowing may have implications for some of the metatheoretical issues concerning consciousness and control. Assuming a distinction between information-based and experience-based metacognitive judgments, it is argued that the sheer phenomenological experience of knowing (''noetic feeling'') occupies a unique role in mediating between implicit-automatic processes, on the one hand, and explicit-controlled processes, on the other. Rather than reflecting direct access to memory traces, noetic feelings are based on inferential heuristics that operate implicitly and unintentionally. Once (...) such heuristics give rise to a conscious feeling that feeling can then affect controlled action. Examination of the cues that affect noetic feelings suggest that not only do these feelings inform controlled action, but they are also informed by feedback from the outcome of that action. (shrink)

Dieses Buch untersucht Humes revolutionäre Theorie des begrifflichen Denkens.Das begriffliche Denken ist eine wichtige Tätigkeit des Geistes. Was genau geschieht im Geist, wenn wir diese Tätigkeit ausüben? Im Vergleich zu anderen Philosophen der Frühen Neuzeit hat Hume bei der Beantwortung dieser Frage eine grössere Schwierigkeit: Humesche Ideen sind (anders als bei Descartes und Locke) rein phänomenaler Natur. Sie sind geistige "Bildchen" ohne begriffliche Struktur. Wie soll das begriffliche Denken mit Hilfe derartiger Ideen möglich sein? Hume reagierte auf diese Herausforderung mit (...) einem völlig neuartigen Ansatz und wurde zum Bahnbrecher einer moderneren Theorie des Denkens. Eine klare Einsicht in diesen Teil der Humeschen Philosophie ist zudem unentbehrlich für ein adäquates Verständnis seines Agnostizismus bezüglich der kausalen Kraft und seiner Metaphysik der Existenz. (shrink)

Animal welfare science and ecology are both generally concerned with the lives of animals, however they differ in their objectives and scope; the former studies the welfare of animals considered ‘domestic’ and under the domain of humans, while the latter studies wild animals with respect to ecological processes. Each of these approaches addresses certain aspects of the lives of animals living in the world though neither, we argue, tells us important information about the welfare of wild animals. This paper argues (...) for the development of a new scientific discipline ‘welfare biology’ to address these issues and more, given the deficiencies of pre-existing life science disciplines to research the subject. Welfare biology is the study of the welfare of all living beings who have a welfare, with a value orientation toward promoting that welfare, regardless of the beings’ situation or relationship to humans and our activities. (shrink)

Philosophy Lab: An Experiential Approach to Conceptual Analysis gives students the skills and strategies needed to do philosophical work in the Analytic tradition. They are presented with a step-by-step method for performing a preliminary conceptual analysis and practice examples to apply the method to standard philosophical problems. Students are introduced to the work of great thinkers including Descartes, Hobbes, Locke, Wittgenstein, and Ryle. These works are complemented by contemporary empirical findings concerning perception, desire, emotion, moral intuition, and other basic elements (...) of explicit intentional cognition. Each chapter features primary source material, commentary, and activity instructions. The activities are designed to allow students to experience each mode of cognition in relative isolation, and then to see how they combine and interrelate in more complex contexts. Finally, students use the template model of conceptual analysis to explore the material. They identify and isolate the concept to be analyzed, determine whether it is simple or complex, and if complex, identify the constituent parts of the concept. Specific topics covered include causal power, sex and marriage, compassion, ambition, justice, and death. Through presentation and modeling the book not only enables student to do conceptual analysis with precision, it helps them understand and interpret philosophical issues. Philosophy Lab is a comprehensive, carefully designed text for first courses in philosophy. It may be used with first-year undergraduate students, advanced high-school students, or adult learners. Asher Walden holds a Ph.D. in philosophy and religion from Drew University. Dr. Walden is currently an adjunct lecturer at the University of Massachusetts, Dartmouth. (shrink)

This paper publishes for the first time 132 conjectures by Nicolaus Heinsius on Ovid’s Metamorphoses 1‒4. The value and possible motivations of each proposal are briefly assessed.