by     H. D. Turner

British Journal of the Philosophy of Science
1960 (61?)

Towards a Unified Cosmology

SCIENTISTS and philosophers often find it difficult to agree as to what constitutes the 'philosophy of science' ; and indeed it has been said that this subject is frequently neither good philosophy nor good science. Such a criticism could not be levelled at this book by Professor Kapp. Towards a Unified Cosmology, as its title implies, is concerned to develop a general theory of Cosmology and to examine its consequences; and the general theory is arrived at by the rigorous application, to possible hypotheses of the past and future extension in time of the material universe, of what is called 'The Hypothesis of Minimum Assumption'.

The Hypothesis of Minimum Assumption is, in effect, Ockham's Razor, or the rule of economy of hypotheses; and it is Professor Kapp's contention that this is, in fact, the most basic of all the principles of physics. According to him the laws of physics are not restrictive in the sense in which laws in statute books are. They do not set out to prohibit any particular event, but allow everything, which is consistent with observable facts, to occur. This, it is suggested, means that every valid generalisation in physics can be stated so that the terms ' any ' and or ' either ' occur in its formulation. Progress towards unification in physics has been most rapid when physicists have acted on this assumption; and when specific assumptions have been made these have always had to be abandoned in favour of non-specific generalisations of the type defined above. The notion that valid generalisation in physics involves the use of die words 'either' or 'any' is formally stated as 'The Principle of Minimum Assumption'.

So far Professor Kapp has been concerned with establishing the philosophical bridgehead from which further advances can be made. Having stated 'The Principle of Minimum Assumption', and described its status and analysed its philosophical basis, he then proceeds to apply it rigorously to the various possible hypotheses about the past and future duration in time of the material universe. There arc three possible hypotheses about the duration of matter and energy in the past: that they have existed for an infinite time; that they have existed for a finite time; and that they have existed for any period of time. There are three corresponding hypotheses about the future duration of matter and energy : that they will exist for an infinite time; that they will exist for a finite time ; and that they will exist for any period of time. There are thus nine possible combinations of these hypotheses, each of which can be used as the basis for the development of a cosmological model. It will be noted, however, that only one of them contains the word 'any' in both its constituent hypotheses. Application of ‘The Principle of Minimum Assumption', therefore, leads Professor Kapp to select this as the only valid generalisation. This philosophically derived hypothesis about the duration of matter and energy in the Universe is stated as follows:

' Any particle of matter or quantum of energy may have existed for any length of time . . . matter and energy are originating without cause, continuously, at random, and not as a result of anything in the existing state of affairs.

Any particle of matter or quantum of energy may cease to exist at any time . . . matter and energy are disappearing without cause, continuously, and by extinction, at random, and not as a result of anything in the existing state of affairs.

This amounts to saying that matter and energy are being continuously created and destroyed, a view first advanced by Professor Kapp some thirty years ago. It is interesting to note that some twelve years ago Bondi and Gold independently arrived at the first part of this hypothesis, although for different reasons, which they published as the Theory of Continuous Creation.

The notion of continuous creation and destruction is called the Hypothesis of the Symmetrical Impermanence of Matter; and it obviously satisfies both the criteria embodied in Ockham's Razor and Professor Kapp's definition of a valid generalisation. Scientific hypotheses, however, must not only conform to philosophical criteria, they must also be predicative. In an observational, as opposed to an experimental, study the predicative capacity of a theory is investigated by using the theory to produce a model in this case a cosmological model. The various properties of the model are then compared in detail with the observed activity in the external Universe; and one's attitude to the theory is then determined by the degree of correspondence exhibited in this comparison.

The cosmological model which is constructed on the basis of the Hypothesis of the Symmetrical Impermanance of Matter has many interesting features. The origin and evolution of the Galaxies is explained in terms familiar to those who have read the theory of continuous creation of Hoyle, Bondi, and Gold. Kapp shows that according to his theory one would expect that new clouds of matter would form in extragalactic space at finite intervals of time, and that their evolution into spiral nebulae should occur during a fairly short period of time during this evolution. The formation of the spiral arms should be accompanied by turbulence in a very large quantity of extremely tenuous gas. Although one would not expect this to lead to the emission of visible radiation it might cause radio-frequency emission. One might, therefore, expect regions in the neighbourhood of extragalactic nebulae to emit radiation - which could be received by radio- telescope; and such observation would be valuable confirmation of this particular cosmological model.

The most unexpected consequences of the Hypothesis of the Symmetrical Impermanence of Matter, however, are obviously those which follow from the hypothesis of the continuous destruction of matter. This leads to some unexpected conclusions. Kapp begins this section of the work by considering the various meanings of the word 'mass'. He distinguishes three meanings: inert mass; attracted (weight) mass; and attracting mass. He goes on to say that General Relativity Theory is based on the identity of inert mass and weight mass but that no satisfactory explanation of attracting mass has ever been given, beyond the statement that a particle carries associated with it, an extensive gravitational potential gradient. Einstein pointed out that in regions of space curvature one can infer that a body free from restraint and possessing inert (and hence ' weight ') mass is accelerated. Now if the body is near an accumulation of inert mass it is observed to be accelerated; and therefore one assumes that space, in the vicinity of an accumulation of inert mass, is curved. This does not show that it is in the nature of inert mass to cause curvature of space but merely that it is in the nature of inert mass to follow curvature. General Relativity Theory goes no further than this; and hence in the past we have merely been able to say that every particle possessing inert mass has associated with it some curvature of space.

If, however, we assume that whenever a particle is created some space is also created, and that similarly when a particle becomes extinct, some space also becomes extinct we may make the following inference. During a particle's continued existence it has no attracting mass, but only inert and weight mass. When it becomes extinct, a local contraction of space occurs which manifests itself as a local curvature of space. This local contraction does not remain stationary, but travels outwards as a pulse ; this constitutes a gravitational field; and thus gravitation is quantised and has a finite velocity of propagation. Furthermore, since the total number of particles becoming extinct in any given period of time in any assemblage is a function only of the total number of particles present two further conclusions follow. The strength of the gravitational field associated with a given number of particles is proportional to that number, and hence bears a constant ratio to the inert and weight mass of the assemblage; and also one may talk about the half-life of matter in the same way in which one discusses the half-life of radio-active elements.

Professor Kapp arrives at a value of about 4 x I08 years for the half-life of matter. If this is so it means that the mass of the Earth and the other planets has been continuously decreasing since the time of their formation. From this follow a number of remarkable astronomical, geological, and biological implications; and one fancies that not all of these will be readily accepted by exponents of these particular disciplines.

One further consequence of the hypothesis that space is intensely curved in the neighbourhood of very dense aggregates of matter is that in the vicinity of atomic nuclei, gravitational forces are sufficient to account for the cohesion of nuclei. It is thus no longer necessary to postulate additional short-range nuclear forces.

The above inadequate resume is sufficient to show that Professor Kapp has produced a very remarkable book, of a type which is all too rarely written. It is essentially readable; it contains very little mathematics; and as has already been pointed out it is concerned in a very proper way with the philosophy of science. One is particularly impressed by the organisation of the material, the cogency of the arguments and the lucidity of the presentation. This book should be read by all those scientists who are concerned with the philosophical bases and status of their subjects and by philosophers who are interested in the development and meaning of scientific theories. Not everyone will agree with all of Professor Kapp's conclusions; but those who disagree will be stimulated by the ideas put forward and one suspects that the author hopes that this may happen. For in this way progress in generalisation in physics will occur; and on this road, ' Towards a Unified Cosmology ' will be a very significant milestone.


Papers by Prof R.O. Kapp and any subsequent discussions and rejoinders are reproduced from the British Journal for the Philosophy of Science with the kind permission of the Oxford University Press.
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