Part One
The Problem

The more we study gravitation, the more there grows upon us the feeling that there is something peculiarly fundamental about this phenomenon to a degree that is unequaled among other natural phenomena. Its independence of the factors that affect other phenomena and its dependence only upon mass and distance suggest that its roots avoid things superficial and go down deep into the unseen, to the very essence of matter and space.

Paul R. Heyl
Scientific Monthly
May, 1954

I

GRAVITATION: STILL A MYSTERY
(Title of article by Paul R. Heyl, Scientific Monthly, May 1954)

GRAVITATION: AN ENIGMA
(Title of article by Robert H. Dicke, American Scientist, March, 1959)

Here is an unintentional but graphic commentary on the progress that has been and is being made toward an understanding of one of the most Conspicuous and most fundamental of all physical phenomena. At the time Heyl wrote his article, almost three hundred years after Newton first grasped the significance of the falling apple and formulated the mathematical expression which represents the gravitational force and enables us to calculate its magnitude with extreme precision, the nature and origin of the phenomenon could still be described as a “mystery.” Five more years of effort by scientists of the highest caliber sufficed only to raise this mystery to the status of an “enigma” : a rather imperceptible advance, to say the least. “It (gravitation) may well be the most fundamental and least understood of the interactions,”¹ Dicke tells us.

Of course, some scientists disagree with this evaluation, and Dicke concedes in his article that many of his colleagues would take exception to the use of the term “enigma” in this connection. However, the record clearly corroborates the opinions of these two specialists in gravitational research. Some progress has been made in the experimental field since Newton’s day, but aside from the accurate measurement of the gravitational constant, the experimental gains have been largely of a negative character; that is, they consist of increasingly precise measurements which demonstrate the absence of certain effects that might be expected, or at least suspected. Progress toward a theoretical understanding has been meager; indeed the growing disillusionment with Einstein’s General Relativity Theory indicates that progress along this line is practically non-existent.

This General Theory is the only major theoretical step taken since Newton, which can even claim to have any factual backing, and while it achieved widespread acceptance initially, doubt as to whether the claims made on its behalf are justified has been increasing as time goes on. As Dicke appraises the situation, “In addition to dissatisfaction with the scanty observational evidence supporting Einstein’s theory of gravitation, there are certain conceptual difficulties which are a source of doubt concerning the complete correctness of the theory in its present form.”² Similar expressions of skepticism are currently being voiced by many other observers. H. Bondi tells us, for example, “The very few and minor points of discrepancy (between Newton’s gravitational theory and Einstein’s) are observationally not too firmly established.”³ Louis de Broglie elaborates this same thought: “The new phenomena predicted by it (the General Theory) are indeed very small and, even when they are actually observed, it can always be asked if they really have their origin in the cause which the theory of Einstein attributes to them, or rather in some other very small perturbation which was neglected in the analysis.”⁴ Werner Heisenberg adds, “For the theory of general relativity the experimental evidence is much less convincing... this whole theory is more hypothetical than the first one (the Special Theory).”⁵ G. J. Whitrow concurs in this appraisal of the observational evidence: “... the General Theory has a far less impressive list of crucial empirical tests to its credit,” and he comments further, “... there is an ambiguity latent in this method (of reducing gravitation to geometry)... Indeed, in developing the theory this ambiguity continually arises.”⁶ Martin Johnson tells us that Einstein followed up his 1905 success with a “less certifiable sequel in 1915 which has in some of its implications led science astray.⁷ Even Henry Margenau, one of the strong supporters of the Relativity doctrine, admits that General Relativity has “suffered a certain loss of glory.”⁸

E. A. Milne may be regarded as somewhat prejudiced on this score, as he is the author of a competing theory, but the mere fact that competent investigators such as Milne see a necessity for some other approach is itself a serious reflection on the adequacy of the General Theory, and Milne’s comments are therefore of interest in this connection. General Relativity, he says, “in the writer’s opinion, is of a nature alien to the main tradition in mathematical physics.”⁹ Bondi sums up the situation: “It (the General Theory) is considered to be correct by a majority of theoretical physicists, but there is a substantial minority that considers it to be wrong or, at least, not established.”¹⁰ The existence of this “substantial minority” is all the more significant when we note the kind of individuals who are included in the group: specialists in gravitational research such as Dicke and Heyl, world-renowned leaders in the field of physics such as Bridgman, de Broglie and Heisenberg, active investigators in the areas where General Relativity should be most applicable, such as Bondi, Whitrow, Johnson and Milne, and so on.

A factor that has contributed heavily to this increasing skepticism as to the validity of the General Theory is that it seems to have arrived at a dead end. One of the criteria by which we are able to recognize a sound physical theory is the manner in which it fits in with existing knowledge in related fields and sheds new light on phenomena other than that for which it was originally constructed. The failure of Einstein’s gravitational theory to accomplish anything of this nature or to show the normal amount of improvement of its own internal structure during the half century that has elapsed since its inception therefore weighs heavily against it. Freeman J. Dyson describes the situation in this manner: “... the view of the world (given by General Relativity)... has remained since 1929 almost totally sterile “.¹¹

But in any event, whether or not these increasing doubts are justified, this theory does not carry gravitational knowledge very far beyond the point where Newton left it. The contributions of the General Theory to an understanding of gravitational processes are greatly overestimated in current scientific thinking. Even if the assertions of the theory were correct, which the succeeding pages will demonstrate that they are not, they do not furnish actual explanations for the things which they purport the explain; they merely push the need for explanation farther into the background where it is less obvious and can more conveniently be disregarded.

Such a statement may seem rank heresy today, at a time when, in spite of the doubts expressed by the more critical observers, Relativity Theory has been elevated to the status of an article of faith on a par with or even superior to the established facts. The textbooks tell us that Newton’s gravitational theory is grossly deficient in that it merely assumes the existence of a gravitational force without giving us any explanation of how such a force originates, and Einstein’s work is hailed as a great theoretical advance that provides us with the explanation which Newton was unable to supply. Typical of the positive and explicit statements to this effect that can be found throughout present-day scientific literature is the following: “Strange as Einstein’s idea (General Relativity) seemed, it was able to explain something which the Newtonian law of gravity had not been able to explain.”¹²

But neither Einstein nor his fellow relativists make any such claim. What they say they have done is to furnish us some good reasons why we should not ask for an explanation.

Willem de Sitter is very explicit about this situation in his book Kosmos. He points out that no one, Einstein or anyone else, has actually explained gravitation, in spite of all the effort that has been devoted to the task: “In the course of history a great number of hypotheses have been proposed in order to ’explain’ gravitation, but not one of these has ever had the least chance, they have all been failures.”¹³

De Sitter then goes on to say that Einstein’s actual accomplishment is to make gravitation identical with inertia, which eliminates the need for an explanation, as “Inertia has from the beginning been admitted as one of the fundamental facts of nature, which have to be accepted without explanation, like the axioms of geometry.”

Einstein himself admits that he cannot give any explanation for the properties with which he is endowing the “space” in which the physical processes represented by his theories take place. “Our only way out,” he says, “seems to be to take for granted the fact that space has the physical property of transmitting electromagnetic waves, and not to bother too much about the meaning of this statement.”¹⁴

In the light of this half-apologetic admission by the originator, some of the present-day encomiums of the theory are nothing short of ridiculous. “... the (general) theory of relativity is a step of almost conclusive power,” says one modern author, “It banishes from physics that occult force of gravity which Newton would not defend, reaching instantaneously across the equally occult idea of void.”¹⁵

How much “conclusive power” can we legitimately attribute to anything that we are asked to “take for granted” without inquiring too closely into its meaning? Is this any less “occult” than the unexplained aspects of Newton’s theories?