Online research in philosophy

The purpose of this paper is twofold: a) to explore the compatibility of Minkowski’s space-time representation of the Special theory of relativity with a dynamic conception of space-time; b) to locate its roots in invariant features - like entropic relations - of the propagation of signals in space-time. From its very beginning Minkowski’s four-dimensional space-time was associated with a static view of reality, e.g. a block universe. Einstein added his influential voice to this conception when he wrote: ‘From a “happening” in three-dimensional space, physics becomes (…) an “existence” in the four-dimensional “world”.’ (Einstein, Relativity 1920, 122) Yet it is by no means clear that Minkowski himself was a believer in the block universe. In his 1908 Cologne lecture on ‘Space and Time’ he speaks of a four-dimensional physics but concedes that a ‘necessary’ time order can be established at every world point. Although the conception of the block universe has gained much currency, an alternative view has been in circulation since the 1910s according to which the trajectories of particles constitute histories in space-time. (Robb 1914, Cunningham 1915, Carathéodorys 1924, Schlick 1917, Reichenbach 1924).

In Physics IV 14, 223a16-223a29 Aristotle raises two questions: (Q1) How is time related to the soul? (Q2) Why is time thought to be in everything? Aristotle's juxtaposition of these questions indicates some relation between them. I argue that Aristotle is committed to the claim that time only exists where change is countable. Aristotle must answer (Q2) in a way that doesn't conflict with this commitment. Aristotle's answer to (Q1) offers him such a way. Since time is change qua countable, time is dependent on souls capable of counting. But the thing that time is, change, is not so dependent. Likewise, time is not located in everything, but change, the substratum of time, is. This answers (Q2) in a way that's compatible with Aristotle's commitments.

A conclusion drawn after a conference devoted (in 1995) to the “arrow of time” was the following: “Indeed, it seems not a very great exaggeration to say that the main problem with “the problem of the direction of time” is to figure out exactly what the problem is supposed to be !” What does that mean? That more than 130 years after the work of Ludwig Boltzmann on the interpretation of irreversibility of physical phenomena, and that one century after Einstein’s formulation of Special Relativity, we are still not sure what we mean when we talk of “time” or “arrow of time”. We shall try to show that one source of this difficulty is our tendency to confuse, at least verbally, time and becoming, i.e. the course of time and the arrow of time, two concepts that the formalisms of modern physics are careful to distinguish.

The conception of time presented in Aristotle’s Physics IV has been supremely influential in the philosophical tradition. However, I shall argue that it proves to be inadequate to resolve a question arising from Aristotle’s own ethics; namely, the relation of ethical action to eudaimonia. As one explores this issue, a sense of time begins to emerge that calls for a reconsideration of the concepts of magnitude or dimension (megethos) and continuity (suneches) that determine the account of time found in Physics IV. This paper sets out the case for such a reconsideration and outlines the impact that it may have on the way we understand the temporal characteristics of eudaimonia.

Or better: time asymmetry in thermodynamics. Better still: time asymmetry in thermodynamic phenomena. “Time in thermodynamics” misleadingly suggests that thermodynamics will tell us about the fundamental nature of time. But we don’t think that thermodynamics is a fundamental theory. It is a theory of macroscopic behavior, often called a “phenomenological science.” And to the extent that physics can tell us about the fundamental features of the world, including such things as the nature of time, we generally think that only fundamental physics can. On its own, a science like thermodynamics won’t be able to tell us about time per se. But the theory will have much to say about everyday processes that occur in time; and in particular, the apparent asymmetry of those processes. The pressing question of time in the context of thermodynamics is about the asymmetry of things in time, not the asymmetry of time, to paraphrase Price ( , ). I use the title anyway, to underscore what is, to my mind, the centrality of thermodynamics to any discussion of the nature of time and our experience in it. The two issues—the temporal features of processes in time, and the intrinsic structure of time itself—are related. Indeed, it is in part this relation that makes the question of time asymmetry in thermodynamics so interesting. This, plus the fact that thermodynamics describes a surprisingly wide range of our ordinary experience. We’ll return to this. First, we need to get the question of time asymmetry in thermodynamics out on the table.

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.

Aristotle begins his famous discussion of time in Book Δ of The Physics by asking whether time belongs to “the things that exist.” In this paper I argue that Aristotle’s apparently ambiguous answer to this question holds one of the keys to clarifying contemporary philosophy of time. First, I argue that the metaphysical and meta-philosophical presuppositions underlying most philosophy of time are deeply flawed. Second, that Aristotle provides us with a much more plausible alternative set of presuppositions about the nature of time. The Aristotelian conception of time as part of the subject matter of physics or “the philosophy of nature” is particularly illuminating. Finally, I examine several issues about the nature and reality of time often raised in the context of contemporary physics and show how the Aristotelian perspective can resolve those puzzles.

What is the difference between time and space? This question, once a central one in metaphysics, has not been treated kindly by recent history. By joining together space and time into spacetime Minkowski sapped some of the spirit out of this project. That is unfortunate, however, for even in relativistic theories there remain sharp and important metrical and topological distinctions between the timelike and spacelike directions of spacetime. Questions about what these differences are, why they exist and how they are related are fascinating. Why, for instance, is time one-dimensional in virtually all physical theories? What does the “minus sign” in the relativistic metric have to do with time? Is there a connection between the two? At a time when researchers in quantum gravity regularly propose speculative theories with no time at all, a better understanding of time in physics is all the more important—even if only to see what is lost by its absence.

Presenting the history of space-time physics, from Newton to Einstein, as a philosophical development DiSalle reflects our increasing understanding of the connections between ideas of space and time and our physical knowledge. He suggests that philosophy's greatest impact on physics has come about, less by the influence of philosophical hypotheses, than by the philosophical analysis of concepts of space, time, and motion and the roles they play in our assumptions about physical objects and physical measurements. This way of thinking leads to new interpretations of the work of Newton and Einstein and the connections between them. It also offers new ways of looking at old questions about a priori knowledge, the physical interpretation of mathematics, and the nature of conceptual change. Understanding Space-Time will interest readers in philosophy, history and philosophy of science, and physics, as well as readers interested in the relations between physics and philosophy.

In the literature on the compatibility between the time of our experience and the time of physics, the special theory of relativity has enjoyed central stage. By bringing into the discussion the general theory of relativity, I suggest a new analysis of the misunderstood notion of becoming, developed from hints in Gödel’s published and unpublished arguments for the ideality of time. I claim that recent endorsements of such arguments, based on Gödel’s own “rotating” solution to Einstein’s field equation, fail: once understood in the right way, becoming can be shown to be both mind-independent and compatible with spacetime physics. Being a needed tertium quid between views of time traditionally regarded as in conflict, such a new approach to becoming should also help to dissolve a crucial aspect of the century-old debate between the so-called A and B theories of time.