Most arguments against the possibility of time travel use the same old, familiar objection: If I could travel back in time, then I could kill my earlier (i.e. younger) self. Since I do exist such an action would result in a contradiction. Therefore time travel is impossible. This is a statement of the Principal Paradox of Time Travel. Some philosophers have argued that such actions as attempting to kill one’s earlier self would always fail and that there is nothing especially (...) strange about such failures. Despite these arguments, the problem generally is not viewed as being solved in favour of time travel. The above objection to time travel is also used to dismiss a particular class of cosmological models as being unphysical. This paper provides a solution to the Principal Paradox by exploring both the logical and causal implications of time travel. (shrink)

On the basis of both logical and physical arguments, a majority of philosophers and physicists have opted for the Block View of time in which this ‘passage’ is purely subjective. However, the feeling of the ‘passage’ of time has been left principally unaccounted for in the Block View. It is argued that there are two ways by which the (apparent) ‘passage’ of time is perceived by human beings and it is the combination of these perceptions that gives rise to the (...) deep-seated impression on the conscious mind of a ‘dynamic’ nature of time. In postulating the existence of a specific kind of intrinsic structural difference between the two orientations of time within the Block View, a basis for these two perceptions may be provided. (shrink)

In this paper, criticisms are made of the main tenets of Professor Mellor's argument against ‘backwards’ causation. He requires a closed causal chain of events if there is to be ‘backwards’ causation, but this condition is a metaphysical assumption which he cannot totally substantiate. Other objections to Mellor's argument concern his probabilistic analysis of causation, and the use to which he puts this analysis. In particular, his use of conditional probability inequality to establish the ‘direction’ of causation is shown to (...) be in error. 1I am indebted to Drs H. Krips, L. O'Neill and to the anonymous referee for their suggestions and critical comments on earlier drafts. (shrink)

The Causal Theory of Quantum Mechanics provides a better understanding of the fundamentals of quantum mechanics than is provided by Orthodox (i.e. Copenhagen) Quantum Theory by describing micro-phenomena in terms of entities and processes in space and time, thereby embracing causality at the quantum level. The book focuses especially on finding solutions to conceptual issues about the nature of energy, the conservation of energy, forces, and the Exclusion Principle within the context of the Causal Theory of Quantum Mechanics.

Whys and Ways of Science presents the issues, arguments and the theories that have attracted the greatest attention and which are covered in the greater majority of tertiary courses offered in philosophical and social studies of science. A primary aim of the book is to present a suitably broad picture of the spectrum of theories about science without sacrificing too much detail. About one-half of the book is devoted to the most influential philosophical theories of science and scientific change to (...) emerge post-World War Two in Western countries, in particular the holistic theories of Thomas Kuhn, Imre Lakatos and Larry Laudan. The second half deals with socially-oriented theories of science such as Functionalist sociology of science; the Strong Programme in the Sociology of Scientific Knowledge; the Interests analysis of science, the theories of Paul Feyerabend and of Bruno Latour. The final chapter examines the question of whether the rationality of science can be sustained in the face of growing accounts of science as a purely social activity and presents an original model for theory choice in science. (shrink)

It is exceedingly frequent for people to speak of the ‘passing of time’. We do not, on the other hand, speak of the ‘passing of space’. There do not seem to be any common locutions concerning spatial passage analogous to those of time’s assumed passage. Further, there is a long held belief in the philosophy of time that there is no spatial analogue of the passage of time. This opinion does not take into account circumstances that cannot be noticed in (...) day-to-day existence and which indicate that there is such a spatial analogue. (shrink)

It is exceedingly frequent for people to speak of the ‘passing of time’. We do not, on the other hand, speak of the ‘passing of space’. There do not seem to be any common locutions concerning spatial passage analogous to those of time’s assumed passage. Further, there is a long held belief in the philosophy of time that there is no spatial analogue of the passage of time. This opinion does not take into account circumstances that cannot be noticed in (...) day-to-day existence and which indicate that there is such a spatial analogue. (shrink)

A recently published hypothesis on the nature of time by physicist Richard A. Muller seeks to provide an objective account of the present moment and the ‘flow’ of time. Muller also claims that his hypothesis makes testable predictions. It is shown that the predictions offered cannot be used to test Muller’s hypothesis, that the hypothesis does not rate scientific status, has a number of questionable metaphysical premises, and is merely a re-fashioning of the Growing Block theory of time.

The essays in this volume of the Australasian Studies in History and Philosophy of Science series are devoted to the subjects of natural kinds, scientific ...

The domains of quantum theory and general relativity overlap in situations where quantum mechanical effects cannot be ignored. In order to deal with this overlap of theoretical domains, there has been a tendency to apply the rules of quantum field theory to the classical gravitational field equations and without much regard for the implications of the whole enterprise. The gravitational version of the asymmetric ageing of identical biological specimens shows that curved spacetime is not dispensable. This result is used to (...) conclude that the particle-based interpretations of quantum gravity are not acceptable. (shrink)

It is exceedingly frequent for people to speak of the ‘passing of time’. We do not, on the other hand, speak of the ‘passing of space’. There do not seem to be any common locutions concerning spatial passage analogous to those of time’s assumed passage. Further, there is a long held belief in the philosophy of time that there is no spatial analogue of the passage of time. This opinion does not take into account circumstances that cannot be noticed in (...) day-to-day existence and which indicate that there is such a spatial analogue. (shrink)

The deBroglie–Bohm quantum potential is the potential energy function of the wave field. The quantum potential facilitates the transference of energy from wave field to particle and back again which accounts for energy conservation in isolated quantum systems. Factors affecting energy exchanges and the form of the quantum potential are discussed together with the related issues of the absence of a source term for the wave field and the lack of a classical back reaction.

The Evolving Block Universe is a model where spacetime continuously emerges leading to a ‘growth’ of spacetime by which there is a passage of time. Its most recent version extends ideas on the passage of time and the various arrows of time (determined by the cosmological evolution of the whole universe). Attention is drawn to some principal problems with this model, especially how the present moment and the passage of time are defined.

Letter to the Editors in response to Alasdair Richmond's 'Time Travelers'.

It has been claimed that kinetic energy is an objective physical quantity whilst at the same time maintaining that potential energy is not. However, by making use of the method of ‘inference to the best explanation’, it may be readily concluded that potential energy is indeed an objective physical quantity. This is done for an example drawn from the foundations of modern chemistry. In order to do so, the criteria of what counts as ‘most probable’ and ‘most reasonable’ are defined (...) and then employed for choosing the best explanation. (shrink)

The perplexing nature of time has been more contemplated, speculated, written, and debated about over the ages than virtually any other subject, with the possible exception of religion. Yet time seems more elusive than the vast majority of other metaphysical concepts. Time remains mysterious, for we lack an understanding of time at a basic physical level. Concepts of time in theories of modern physics and time as found in contemporary western analytic philosophy are discussed.

Most people would probably agree that the obvious feature about time is that it progresses (or flows). However, our everyday experience of the apparent ‘dynamic’ nature of time conflicts with the basic laws of physics which do not posit any passage of time. This clash between experience and fundamental physics has led a few physicists to develop theories of the universe in which time’s passage is an explicit feature. Two such theories are discussed along with a possible non-‘dynamic’ alternative.