The cosmological constant problem arises at the intersection between general relativity and quantum field theory, and is regarded as a fundamental problem in modern physics. In this paper, we describe the historical and conceptual origin of the cosmological constant problem which is intimately connected to the vacuum concept in quantum field theory. We critically discuss how the problem rests on the notion of physically real vacuum energy, and which relations between general relativity and quantum field theory are assumed in order (...) to make the problem well-defined. (shrink)

The Casimir force between two neutral metallic plates is often considered conclusive evidence for the reality of electromagnetic zero-point fluctuations in ‘empty space’. However, it is not well known that the Casimir force can be derived from many different points of view. The purpose of this note is to supply a conceptually oriented introduction to a representative set of these different interpretations. The different accounts suggest that the Casimir effect reveals nothing conclusive about the nature of the vacuum.

The Casimir force between two neutral metallic plates is often considered conclusive evidence for the reality of electromagnetic zero-point fluctuations in 'empty space' (i.e. in absence of any boundaries). However, it is not well known that the Casimir force can be derived from many different points of view. The purpose of this note is to supply a conceptually oriented introduction to a representative set of these different interpretations. The different accounts suggest that the Casimir effect reveals nothing conclusive about the (...) nature of the vacuum. (shrink)

The Casimir force between two neutral metallic plates is often considered conclusive evidence for the reality of electromagnetic zero-point fluctuations in ‘empty space’. However, it is not well known that the Casimir force can be derived from many different points of view. The purpose of this note is to supply a conceptually oriented introduction to a representative set of these different interpretations. The different accounts suggest that the Casimir effect reveals nothing conclusive about the nature of the vacuum.

It is well known that Niels Bohr insisted on the necessity of classical concepts in the account of quantum phenomena. But there is little consensus concerning his reasons, and what he exactly meant by this. In this paper, I re-examine Bohr’s interpretation of quantum mechanics, and argue that the necessity of the classical can be seen as part of his response to the measurement problem. More generally, I attempt to clarify Bohr’s view on the classical/quantum divide, arguing that the relation (...) between the two theories is that of mutual dependence. An important element in this clarification consists in distinguishing Bohr’s idea of the wave function as symbolic from both a purely epistemic and an ontological interpretation. Together with new evidence concerning Bohr’s conception of the wave function collapse, this sets his interpretation apart from both standard versions of the Copenhagen interpretation, and from some of the reconstructions of his view found in the literature. I conclude with a few remarks on how Bohr’s ideas make much sense also when modern developments in quantum gravity and early universe cosmology are taken into account. (shrink)

A short review of some recent developments in the philosophy of physics is presented. I focus on themes which illustrate relations and points of common interest between philosophy of physics and three of its `neighboring' elds: Physics, metaphysics and general philosophy of science. The main examples discussed in these three `border areas' are decoherence and the interpretation of quantum mechanics; time in physics and metaphysics; and methodological issues surrounding the multiverse idea in modern cosmology.

By analyzing the meaning of time I argue, without endorsing operationalism, that time is necessarily related to physical systems which can serve as clocks. This leads to a version of relationism about time which entails that there is no time 'before' the universe. Three notions of metaphysical 'time' (associated, respectively, with time as a mathematical concept, substantivalism, and modal relationism) which might support the idea of time 'before' the universe are discussed. I argue that there are no good reasons to (...) believe that metaphysical 'time' can be identified with what we ordinarily call time. I also briefly review and criticize the idea of time 'before' the big bang, associated with some recent speculative models in modern cosmology, and I argue that if the big bang model is a (roughly) correct description of our universe, then the best current answer to the question in the title is that time did have a beginning. (shrink)

During the last three decades, there has been a growing realization among physicists and cosmologists that the relation between particle physics and cosmology may constitute yet another successful example of the unity of science. However, there are important conceptual problems in the unification of the two disciplines, e.g. in connection with the cosmological constant and the conjecture of inflation. The present article will outline some of these problems, and argue that the victory for the unity of science in the context (...) of cosmology and particle physics is still far from obvious. (shrink)

Norton has recently argued that causation is merely a useful folk concept and that it fails to hold for some simple systems even in the supposed paradigm case of a causal physical theory – namely Newtonian mechanics. The purpose of this article is to argue against this devaluation of causality in physics. My main argument is that Norton’s alleged counterexample to causality within standard Newtonian physics fails to obey what I shall call the causal core of Newtonian mechanics. In particular, (...) I argue, Norton’s example is not in conformity with Newton’s first law. Moreover, Norton’s reformulation of this first law seems insufficient as a replacement for the original version since the notion of inertial frames in the resulting reformulated theory lacks a physical justification, and since an intelligible notion of time in Newtonian mechanics appears to be closely tied to Newton’s first law in its standard form. I will finally suggest how, given a plausible relationist account of time, the causal core of Newtonian mechanics may play a central role also in relativity and quantum theory. (shrink)

This paper investigates some of the philosophical and conceptual issues raised by the search for a quantum theory of gravity. It is critically discussed whether such a theory is necessary in the first place, and how much would be accomplished if it is eventually constructed. I argue that the motivations behind, and expectations to, a theory of quantum gravity are entangled with central themes in the philosophy of science, in particular unification, reductionism, and the interpretation of quantum mechanics. I further (...) argue that there are —contrary to claims made on behalf of string theory— no good reasons to think that a quantum theory of gravity, if constructed, will provide a theory of everything, that is, a fundamental theory from which all physics in principle can be derived. (shrink)

The cosmological constant problem arises at the intersection between general relativity and quantum field theory, and is regarded as a fundamental problem in modern physics. In this paper we describe the historical and conceptual origin of the cosmological constant problem which is intimately connected to the vacuum concept in quantum field theory. We critically discuss how the problem rests on the notion of physically real vacuum energy, and which relations between general relativity and quantum field theory are assumed in order (...) to make the problem well-defined. (shrink)

In this manuscript we initiate a systematic examination of the physical basis for the time concept in cosmology. We discuss and defend the idea that the physical basis of the time concept is necessarily related to physical processes which could conceivably take place among the material constituents available in the universe. As a consequence we motivate the idea that one cannot, in a well-defined manner, speak about time ‘before’ such physical processes were possible, and in particular, the idea that one (...) cannot speak about a time scale ‘before’ scale-setting physical processes were possible. It is common practice to link the concept of cosmic time with a space-time metric set up to describe the universe at large scales, and then define a cosmic time t as what is measured by a comoving standard clock. We want to examine, however, the physical basis for setting up a comoving reference frame and, in particular, what could be meant by a standard clock. For this purpose we introduce the concept of a `core' of a clock and we ask if such a core can - in principle - be found in the available physics contemplated in the various `stages' of the early universe. We find that a first problem arises above the quark-gluon phase transition where there might be no bound systems left, and the concept of a physical length scale to a certain extent disappears. A more serious problem appears above the electroweak phase transition believed to occur at $\sim 10^{-11}$ seconds. At this point the property of mass disappears and it becomes difficult to identify a physical basis for concepts like length scale, energy scale and temperature - which are all intimately linked to the concept of time in modern cosmology. This situation suggests that the concept of a time scale in `very early' universe cosmology lacks a physical basis or, at least, that the time scale will have to be based on speculative new physics. (shrink)

We examine the necessary physical underpinnings for setting up the cosmological standard model with a global cosmic time parameter. In particular, we discuss the role of Weyl's principle which asserts that cosmic matter moves according to certain regularity requirements. After a brief historical introduction to Weyl's principle we argue that although the principle is often not explicitly mentioned in modern standard texts on cosmology, it is implicitly assumed and is, in fact, necessary for a physically well-defined notion of cosmic time. (...) We finally point out that Weyl's principle might be in conflict with the wide-spread idea that the universe at some very early stage can be described exclusively in terms of quantum theory. (shrink)

Conditions for description are general rules to which language must conform if it is to serve descriptive purposes. It is argued that the existence of such rules renders scepticism about them incoherent. The only way we can decide whether or not there are such conditions is by seeing in practice whether or not there are certain rules such that we cannot in fact break them without making language unfit for describing. The case is similar to that of, e.g., the law (...) of contradiction, which is itself a condition for description. If we find other conditions, the sceptic, like anyone else, will have to accept that he is bound by them no less than he is bound by the law of contradiction. (shrink)

It is generally agreed that the argument about Achilles and the tortoise was intended to prove that the concept of movement was contradictory or ambiguous and therefore that it did not belong in the foundations of ontology. It is suggested here that the argument stands unless we are prepared to define a standard time by means of dynamical concepts. It would be a premature assumption, however, to suppose that Zeno himself should have been so prepared.

Terence Irwin's edition of the Nicomachean Ethics offers more aids to the reader than are found in any modern English translation. It includes an Introduction, headings to help the reader follow the argument, explanatory notes on difficult or important passages, and a full glossary explaining Aristotle's technical terms. The Third Edition offers additional revisions of the translation as well as revised and expanded versions of the notes, glossary, and Introduction. Also new is an appendix featuring translated selections from related texts (...) of Aristotle. (shrink)

This volume offers a collection of in-depth explorations of pragmatism as a framework for discussions in philosophy of science and metaphysics. Each chapter involves explicit reflection on what it means to be pragmatist, and how to use pragmatism as a guiding framework in addressing topics such as realism, unification, fundamentality, truth, laws, reduction, and more. -/- .

كتاب بحصي يتناول الصراع بين الصوفية والسلفية ويتناول قصة حياة الحلاج وابن الفارض والسهروردي ودواوينهم ويتناول الحب الإلهي عند الصوفية.

"First published by Oxford University Press, 1916."--Title page verso.

An English language translation accompanies the original Greek text of Aristotle's book about the nature of the state, constitutions, revolutions, democracy, and oligarchy.

This is the first complete, one-volume English translation of the ancient Chinese text Xunzi, one of the most extensive, sophisticated, and elegant works in the tradition of Confucian thought. Through essays, poetry, dialogues, and anecdotes, the Xunzi articulates a Confucian perspective on ethics, politics, warfare, language, psychology, human nature, ritual, and music, among other topics. Aimed at general readers and students of Chinese thought, Eric Hutton’s translation makes the full text of this important work more accessible in English than ever (...) before. Named for its purported author, the Xunzi has long been neglected compared to works such as the Analects of Confucius and the Mencius. Yet interest in the Xunzi has grown in recent decades, and the text presents a much more systematic vision of the Confucian ideal than the fragmented sayings of Confucius and Mencius. In one famous, explicit contrast to them, the Xunzi argues that human nature is bad. However, it also allows that people can become good through rituals and institutions established by earlier sages. Indeed, the main purpose of the Xunzi is to urge people to become as good as possible, both for their own sakes and for the sake of peace and order in the world. In this edition, key terms are consistently translated to aid understanding and line numbers are provided for easy reference. Other features include a concise introduction, a timeline of early Chinese history, a list of important names and terms, cross-references, brief explanatory notes, a bibliography, and an index. (shrink)

This incisive book deals with the use of the criminal law to enforce morality, in particular sexual morality, a subject of particular interest and importance since the publication of the Wolfenden Report in 1957. Professor Hart first considers John Stuart Mill's famous declaration: "The only purpose for which power can be rightfully exercised over any member of a civilized community is to prevent harm to others." During the last hundred years this doctrine has twice been sharply challenged by two great (...) lawyers: Sir James Fitzjames Stephen, the great Victorian judge and historian of the common law, and Lord Devlin, who both argue that the use of the criminal law to enforce morality is justified. The author examines their arguments in some detail, and sets out to demonstrate that they fail to recognize distinction of vital importance for legal and political theory, and that they espouse a conception of the function of legal punishment that few would now share. (shrink)

A classic exposition of Kant's ethical thought.