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Fundamental Queries

In the present paper it is shown how it is possible by means of a time-based concept of equidistance to construct a spatial geometry for relativistic cosmology. In analogy to a sphere defined as the geometrical site for all those points which are equidistant from a given point, we construct a plane as the site for all those points that are equidistant from two points, and a line as the site for all those points equidistant from three points. Having defined parallellity and perpendicularity, we proceed to define the Cosmic Substrate in a way analogous to the cosmological principle of the Cusan. Assuming that we can always construe the center point for any three non-collinear members of this Substrate, we can prove simultaneity to be universally transitive for all members of the Substrate if the simultaneity is defined indirectly by means of equidistance.

Revised version (30.12.2008).

In the present paper it is shown how it is possible to use the strict "light principle" as a point of departure for deriving three new "steady state" models of the universe which are at variance with the Robertson Walker Metric but fulfill Milne's cosmological principle.

Contents

A. Introduction

1. A simple derivation of LT
2. Importance of the gamma-factor
3. The formal reduction of LT to GT
4. From "big bang" to "steady state"
5. Our basis: the strict "light principle"
6. The cosmological principle of Milne
7. A new model of continuous creation
8. Two asymptotic approximations
9. The gamma-factor in disguise

O. Conclusion

Revised version. This paper was written in honour of Franco Selleri, faithful defender of reason in physics, who committed his efforts to "the liberation of time from the enslavement to space". - Pointing to the cleft between the idea of a temporal evolution, central to modern biology, and the idea of the timelessness of reality derived from the relativization of simultaneity and followed by the fusion of space and time into space-time, both fundamental to modern physics, the paper demonstrates that the standard definition of time at a distance is beset with ambiguities that might be solved by making a fresh start which takes its point of departure in the idea of a Cosmic Time, as proposed by the British Tradition of relativistic cosmology.

Revised version (20.12.2008).

Accepting clock retardation as an empirical fact, we provisionally adopt Whitrow's derivation of the Robertson-Walker Metric (RWM) of Cosmology from the gamma-factor of SR. Recalling the fact that the principle of cosmic isotropy can be used as an argument for the definability of an all-embracing universal time, at least statistically, we propose to reverse this procedure by postulating such time as a regulative idea in the sense of Kant. Taking RWM as our formal point of departure we next investigate the properties of two standard models of modern cosmology: !) the uniform expansion model of Milne & Prokhovnik, which is the simplest model of a cosmic "big bang", and 2) the exponential expansion model of Bondi & Gold, supposed to be the simplest model of a cosmic "steady state". Rejecting the so-called "perfect cosmological principle" of the latter, it is easy to show that the ideas of "big bang" and "steady state" may not be mutually exclusive after all: a universe starting with a "big bang" at the dawn of creation may approximate to a "steady state" in the course of infinite time. We further consider the relationship between our choice of time scale for a particular model of the universe and its corresponding space metric. As it turns out, there are at least two important ways of mapping the expansion of the universe: a) that which keeps atomic sizes constant while light is being stretched, and b) that which keeps distances between fundamental particles constant while their constituents are shrinking. Finally a new model of the universe is proposed which deviates from RWM by allowing the curvature of space to vary with distance. In this model the curvature of space appears to increase with the distance at which an object is observed by a fundamental observer. The model suggested is a new "steady state" model which is even simpler than that of Bondi & Gold in the sense that it implies an absolute structural identity between "world map" and "world view", in agreement with the "no-horizon" principle of Milne. The basic properties of this model and two other related ones are examined and discussed.

Revised version.

1. Cosmology, a Science?
2. Milne's 'Kinematic' Relativity
3. Walker's Analysis of Milne's Ideas
4. Revolt Against Prejudice in Science!
5. Theories of Continued Creation
6. A Program for Synthesis

In our time, Cosmology is generally acknowledged to be the science of the universe. But what is the universe? Is it being, entity, or substance? Is it nature itself, ultimate reality? How do we overcome the desperate difficulties of speaking sensibly of everything at once? And in what sense can such an elusive subject be the object of anything like a real science? Can we avoid the danger of assuming either too little or too much even before we begin? Finally, the universe is one, or unique: how can it then give rise to a legitimate science at all such questions cry for their rational answers ... Hoping for better progress later, we shall start by making our language a bit more precise.

As one of the rather few philosophers attending the biennial conferences on the Physical Interpretations of Relativity Theory from their start in 1988 until 1998, ten years later, I would like to take this opportunity to assess the import of the various contributions offered by these conferences from a philosophical point of view, in order to give some clues as regards the perspectives of future progress in this field of physics. Throughout the past decade all our conferences have been sponsored by THE BRITISH SOCIETY FOR THE PHILOSOPHY OF SCIENCE. For that reason it may not seem imposterous for a philosopher to assume this task.

The present paper is dedicated to the honour of Ths.E. Phipps j. It is argued that Special Relativity (SR) should be rejected in favour of a Classical Alternative (AR) based on the invariance of proper time; this involves a modification of Einstein's second postulate which allows the one-way light-speed to vary, their average speed being invariant.

Presented at the 1st Internat. Poincare Conf., 1994, International Academy for the Philosophy of Science.

Revised Version of Paper Published by ACERHP 1996, 'Philosophia Scientia', cahiers special.

The merits of Poincare as one of the greatest mathematicians of all times are globally acknowledged, but the value of his conventionalist theory of science is still greatly underestimated, and his contributions to physics and its philosophy have unjustly fallen into oblivion. The aim of the present paper is to stress the importance of Poincare to physical theory and the theory of physics by hailing him as the principal figure in the interplay between classical philosophy and modern cosmology.