The empirical study of visual space has centered on determining its geometry, whether it is a perspective projection, flat or curved, Euclidean or non-Euclidean, whereas the topology of space consists of those properties that remain invariant under stretching but not tearing. For that reason distance is a property not preserved in topological space whereas the property of spatial order is preserved. Specifically the topological properties of dimensionality, orientability, continuity, and connectivity define “real” space as studied by physics and are the (...) spatial properties that characterize the physical universe as being an integral whole. By contrast the geometrical analysis of VS has taken little cognizance of its topology. Instead such properties have been presupposed a priori rather than being established a posteriori by empirical means, perhaps because these properties are self-evident. Applying the method of coordinative definition expounded by Hans Reichenbach for determining geometrical and topological properties of physical space, it can be shown that VS fulfills the topological criteria of being a “real” space sui generis. Though theorized to be produced by the brain, the topology of VS is not topologically equivalent with the structure and activity of the brain because, as will be shown, the topology of VS cannot be formed from the topology of the brain without tearing and/or cutting and pasting. (shrink)

Might something I do now make something have happened earlier? This paper is about an argument which concludes that I might. Some arguments about “backward causation” conclude that the world could have been the kind of place in which actions make things have happened earlier. The present argument says that it is that kind of place: that we actually are continually doing things that really make earlier things have happened. The argument is not new. It sees temporal direction as logically (...) independent of any direction which necessary and sufficient conditions may have and it sees causal direction as properly deriving from the latter. Thus the directions of time and of making things happen need not coincide and, as it turns out, do not actually coincide in fact. There are examples of events which are sufficient, in a suitably rich sense, for the occurrence of earlier events; hence they make the earlier events happen. My purpose in this paper is to lend support to the argument by filling in some details which ‘backward sufficient conditions’ may lay claim to. (shrink)

Most relational theories assert both that spatial discourse is reducible to talk about physical objects and their spatial relations, and that the relation of congruence derives from a non-metrical relation which intervals bear or possibly bear to measuring instruments. We have shown that there are serious logical difficulties involved in maintaining both these positions and the thesis of the continuity of space. We have also shown that Grünbaum's motivating argument for the reduction of congruence is unsound, and, moreover, that the (...) prospects of formulating the kind of definition which this reduction requires seem to rest upon a wholly vague notion of physical possibility. Alternatively, if congruence is taken as primitive, it seems plausible that spatial discourse can be reconstructed so that there is no ontological commitment to spatial objects other than physical objects. Whether or not this relational thesis is ultimately defensible requires more elaboration of the relational theory, and investigation of its role in the formalizations of current physical theories. It is odd, considering the wide currency of relational theories, that this work has never been done. (shrink)

The traditional absolutist-relationist controversy about space and time conflates four distinct issues: existence, abstraction, relationality and relativity. Terms which are relational, relative or abstract may denote items which possess contingent properties. Possession of such properties, including topological and geometrical properties, is therefore no indication of logical type. To fail to recognise the possibility of spaces, times and space-times of various logical types is to risk conflating two distinct ontological issues: a metaphysical issue concerning the existence of abstract objects and a (...) question of physics concerning the existence of causally efficacious substrata which may or may not be needed to explain the contingent properties of the abstract objects. (shrink)

The debate on the ontological status of spacetime in General Relativity has historically seen two principal philosophical contenders: substantivalism, roughly the view that holds that spacetime exists apart from the material contents of the universe, and relationism, the doctrine that spacetime does not exist, i.e., it is a mere abstract web of spatiotemporal relations among bodies. This dispute, however, has rarely been fought on a cosmological battlefield. In this paper an attempt in this direction is made. The question at issue (...) is the following: is there any feature of our universe that requires or is best explained in terms of a substantival space? I claim that there is indeed: the expansion of the universe, perhaps the most important phenomenon in cosmology, can play such a role. (shrink)

On propose quelques réflexions sur le concept de temps, tout d'abord rappelant la diversité des expériences et des consciences du temps, et montrant comment le temps des sciences et de la physique est relié à cette expérience et à cette conscience qui en est prise, notamment en ce qui concerne le rapport entre l'instant et la durée. On s'efforce ensuite de tirer deux leçons des développements sur le concept de temps tel qu'il se présente en physique. La première est que (...) le concept de temps est construitpar la pensée, et ne nous est pas directement donné, soit par la nature, soit par notre «sens interne». Cela apparait, notamment, avec l'introduction du temps comme paramètre de la dynamique par Galilée, puis avec la définition du temps «absolu et mathématique » par Newton en vue de constituer le «temps instantané» de la loi fondamentale de la mécanique, et enfin avec la critique des limites de cette conception qui aboutit à la formulation de la relativité du temps et de son lien de constitution à l'espace (construction de l'espace-temps). La seconde leçon est que le temps se définit et se détermine par les phénomènes(et les objets) de la nature (qui se ramènent aux propriétés de la matière), alors qu'on a longtemps cru l'inverse. Cela apparait notamment avec la soumission du temps, dans la reconstruction du concept effectuée par Einstein, d'abord à des principes physiques(avec la relativité restreinte), ensuite avec sa détermination, conjointement à l'espace (dans l'espace-temps), par les champs de gravitation, qui sont des propriétés de la matière. Ce caractère est également confirmé par la deuxième loi de la thermodynamique et par les développements récents de la cosmologie. (shrink)