# The Spike or Victoria University College Review 1945

# Physics and Reality

## Physics and Reality

It is the aim of science, and of the scientist, to reduce all observables to a rational scheme That is, not to attempt to deduce the nature of the unobservable parts of existence, after the metaphysical manner, but to correlate sense data, and make verifiable predictions of probable future experience in the light of present appearance. Let the philosopher prove with complete logic that the scientific scheme lacks "reality." To the pragmatical scientist, these speculations are irrelevant unless they lead to observable and measurable results.

Physics, which is concerned with those phenomena which are attributed to matter in its simplest and most primitive forms, is traditionally the home of the materialist. Yet in its most modern developments it has fostered strongly idealist philosophies from some competent physicists. The cause is of interest, and has an important bearing on the general question.

Closely interwoven with all physical science is the study of mathematics, contributing its peculiar elegance and its especial difficulty. The two are inseparable, because physics is concerned primarily with those sense data which Eddington called "pointer readings." When we measure something, we have some real information about it. The logic of numbers is clearer than that of abstract ideas. It happens to be more profitable to predict the behaviour of a system by constructing and solving its differential equations than by pondering qualitatively on the whole complex of causes and effects.

In calculating our physical theory, we set up a hypothetical mathematical model, of which the physical system is an approximation. This is, in general the most difficult step. Mathematics, up to now is ahead of physics, and once we have decided on the most suitable model the analysis is not always so difficult.

But there lies the danger. In setting up our hypothetical mathematical model, we are liable to forget that its elements have existence external to mathematics. So obsessed do we become with the niceness of our calculations that we fail to check them back against the external world. Theories of a mathematical nature are essential to physics, but they are useless unless at some stage or another they are linked with the results of experiments.

Pure mathematics may be to blame. On the whole, mathematicians, as they work, have the impression that they are discovering, not inventing. There is a feeling that the answer to the problem "really" exists, if we only knew how to find it. This is partly because logically, the axioms and postulates contain implicitly the whole structure of theorems. But many philosophers and mathematicians consider that it is a fallacy and that men invent the mathematics they require. In the long run, this is probably so, the main trends being conditioned by circumstances. Yet no man who has "discovered" a mathematical "truth" will admit that he just made it up. The validity of mathematics as a logical study is undeniable, but no one can decide whether it is created by God or man.

The difficulty is that we may find a mathematical theory which fits the facts of experience, without being able to interpret physically the elements involved. It is impossible to conceive of an electron or a wave packet, or a four-dimensional space time. They are page 64 mere logical constructs, extrapolated from the experience which we think we understand, to facilitate calculation. It is interesting to note that trend in modern physics, exemplified by the thermodynamics, wavemechanics and relativity theory, which lays emphasis on linking theory with practice by giving mathematical expression to our inability to make certain measurements, such as the simultaneous position and velocity of a particle, or of the "absolute" velocity of a system.

To the practising physicist, these considerations are seldom apparent. He is not worried about the nature of the inconceivable things which turn up in the equations. He does not doubt their existence, for by appropriate manipulation he gets the results he expects. Their properties are defined solely by the equations in which they occur. On the whole, most physicists in their scientific work are materialists and mechanists. There is no point in doubting the existence of matter if you are studying its properties. It is reasonable to assume that there is "something" there. Not that this implies the spherical red particles of the Victorians. The position has been very clearly stated by Lenin.

"When the physicists say 'matter disappears' they mean by this that until the present, the natural sciences had reduced their measurements of the physical realm to three ultimate concepts, matter, electricity, and ether; and that now only the last two remain, for they have succeeded in reducing matter to electricity . . . For the sole 'property' of matter with the recognition of which materialism is vitally concerned is the property of being 'objective reality,' of existing outside of our cognition."

This is the generally accepted view of physicists today, at least in their scientific writings.