Online research in philosophy

In Time as History, a collection of his 1969 Massey lectures, George Grant reviews the thought of Nietzsche and concludes that the conception of time as history ...

It is argued that the main problem with "the problem of the direction of time" is to figure out what the problem is or is supposed to be. Towards this end, an attempt is made to disentangle and to classify some of the many issues which have been discussed under the label of 'the direction of time'. Secondly, some technical apparatus is introduced in the hope of producing a sharper formulation of the issues than they have received in the philosophical literature. Finally, some tentative suggestions about the central issues are offered. In particular, it is suggested that entropy and irreversibility are much less crucial to the central issues than most philosophers would have us believe. This suggestion is not made because of any firm conviction of its correctness but rather because it helps to focus the discussion on some basic but long neglected assumptions which underlie traditional approaches.

David Albert's Time and Chance (2000) provides a fresh and interesting perspective on the problem of the direction of time. Unfortunately, the book opens with a highly non-standard exposition of time reversal invariance that distorts the subsequent discussion. The present article not only has the remedial goal of setting the record straight about the meaning of time reversal invariance, but it also aims to show how the niceties of this symmetry concept matter to the problem of the direction of time and to related foundation issues in physics.

The impression is frequently given that the static description of the 4-dimensional world given by a tenseless theory of time adequately accounts for the world and that a tensed theory of time has nothing to offer. In fact, the tenseless theory of time leaves us incapable of specifying the direction of time, whereas a tensed theory of time enables us to do so. Thus, the tensed theory enjoys a considerable advantage over the tenseless view.

Many phenomena in the world display a striking time-asymmetry: the forwards transition frequencies are approximately invariant while the backwards ones are not. I argue in this paper that theories of such phenomena will entail that time has a direction, and that quantum mechanics in particular entails that the future is objectively different from the past.

Extending work of Wittgenstein, Lakoff and Johnson I suggest that it is the (spatial) metaphors we rely on in order to conceptualise time that provide an illusory space for time-travel-talk. For example, in the “Moving Time” spatialisation of time, “objects” move past the agent from the future to the past. The objects all move in the same direction – this is mapped to time always moving in the same direction. But then it is easy to imagine suspending this rule, and asking why the objects should not start moving in the opposite direction. This is one way of generating the idea of time-travel “back” into the past. Time-travel-talk essentially involves the unaware projection of fragments of our time-talk – taken from powerful conceptual metaphors – onto the nature of reality itself. Understanding this dissolves away the charm and attractions of such talk.

While experience tells us that time flows from the past to the present and into the future, a number of philosophical and physical objections exist to this commonsense view of dynamic time. In an attempt to make sense of this conundrum, philosophers and physicists are forced to confront fascinating questions, such as: Can effects precede causes? Can one travel in time? Can the expansion of the Universe or the process of measurement in quantum mechanics define a direction in time? In this book, researchers from both physics and philosophy attempt to answer these issues in an interesting, yet rigorous way. This fascinating book will be of interest to physicists and philosophers of science and educated general readers interested in the direction of time.

The final work of a distinguished physicist, this remarkable volume examines the emotive significance of time, the time order of mechanics, the time direction of thermodynamics and microstatistics, the time direction of macrostatistics, and the time of quantum physics. Coherent discussions include accounts of analytic methods of scientific philosophy in the investigation of probability, quantum mechanics, the theory of relativity, and causality. "[Reichenbach’s] best by a good deal."—Physics Today. 1971 ed.

The frequencies with which photons pass through half-silvered mirrors in the forward direction of time is always approximately 1/2, whereas the frequencies with which photons pass through mirrors in the backward direction in time can be highly time-dependent. I argue that whether one should infer from this time-asymmetric phenomenon that time has an objective direction will depend on one's interpretation of quantum mechanics.