Later this year, the Planetary Society is planning to launch LightSail-1, a sail that will travel farther and farther into space propelled by the sun's steady stream of photon particles. Other such flights are projected for the next few years. This renewed interest in light and its momentum call for a fresh look into the speed of light c which generates this energy. This speed has been, for over a century, a cardinal pillar supporting the present edifice of theoretical physics, but that light had any speed at all was discovered only in the seventeenth century, and confirmed in the eighteenth, by means of measurements over vast astronomical distances. These methods seem to have proven that the speed of light varied with the speed of the observer. Nonetheless, another experiment late in the nineteenth century, was interpreted as showing that the speed of light was independent of its observer or its source-it was a universal constant. This thesis is a meticulous examination in historical context of the evidential data and theories which paved the road to the idea that the speed of light was a universal constant, a seemingly universal belief. The need for the endeavor arose secondarily to the main task of exploring fundamental physical and geometrical phenomena of light detailed in the previous treatises on Optokinetics.

C The Speed of Light

A Tale of Scientific BlunderBy Harry H. Mark

iUniverse, Inc.

Copyright © 2010 Harry H. Mark
All right reserved.
ISBN: 978-1-4502-2286-0

Contents

PREFACE..............................................VIIDEFINITIONS..........................................1MAN..................................................4SPACE................................................9TIME.................................................24MOTION...............................................34LIGHT................................................45LINEAR MOTIONS IN MOVING FRAMES......................58ARISTOTLE............................................60ORESME...............................................62COPERNICUS...........................................66KEPLER...............................................69GALILEO..............................................73NEWTON...............................................76OPTOKINEMATICS.......................................84SPEED IN LINE OF SIGHT...............................87RED SHIFT............................................103SPEED IN PERPENDICULAR DIRECTION.....................116SPEED IN BOTH DIRECTIONS.............................125INTERPRETATIONS......................................140REFLECTIONS..........................................153EPILOGUE.............................................158NAME INDEX...........................................162

Chapter One

Definitions

Names and words often mean different things to different people, and since we cannot smell them, a rose may not be a rose by any other name. Definitions are essential in telling us who is who and what is what so that we do not confuse the elements in the story that follows. What follows here is an attempt on our part to understand an event in nature-light-and we begin by introducing the terms by which we define nature. "The first cause of absurd conclusions I ascribe to the want of method; in that they begin not their ratiocination from definitions"

This quest to define the natural world-to tell the nature of Nature-is as old as civilization itself, and was usually in the purview of Metaphysics (originally a book written by Aristotle after his Physics) which treats mainly of topics unrelated to experience, best known among them being Mathematics: "Scientists have learned that the starting-point of their investigations does not lie solely in the perception of the senses, and that science cannot exist without some small portion of metaphysics."

But for our purposes we need definitions that relate to the reality of the world as perceived by our senses and conceived by physiological thought processes-defined terms that aid comprehension of real natural phenomena. Thus the definitions here are not presented with a purpose of forming a logical system of axiomatic premises whence our knowledge is then deduced by a strict mental discipline, but are meant merely to describe the milieu in which the events that follow occur. We attempt to employ Francis Bacon's method of evidence-based epistemology as the proper induction to reliable knowledge, appreciating that this empiricism was derived from the ancient Greek word for practitioners of medicine called "empirics".

MAN

The existence of man is axiomatic; namely, it cannot be proved or disproved by man, and hence must be accepted for granted, a priori. The axiomatic nature of man seems at first puzzling; historians and anthropologists assure us that there was a time when man did not exist, and present developments are sufficient reason to fear that he will soon cease to exist. But these considerations emanate from man himself, it is he who says so. Logically no thing can possibly be proven or demonstrated by the thing itself, which leaves no choice but to accept the axiom of man.

A lone person on an island cannot prove his existence. Unless some signal from him or his remains is received by the rest of mankind, he does not exist. His reality is not fact nor truth, for there is no way of demonstrating it. He can still prove his existence to the fish, but then the fish must take their own being as an a priori fact. What the man on the island lacks is another human frame of reference. Man may imagine a world without man, but it is man who does the imagining. All human endeavors-including science- begin with man, even though man himself cannot be proven or demonstrated.

Early in his history man evolved a concept named 'truth', often given by a superior divine or secular power, and at least on one occasion chiseled in stone on Mount Sinai. When in the Renaissance blind emotional faiths were gradually replaced by more enlightened rational thoughts the concept of transcendental truth remained but its contents changed. Scientists, as theologians before them, often optimistically believed that their truths were self-propelled by some innate power of passive buoyancy which, like oil in water, must sooner or later rise to the surface-vincit omnia veritas. Belief in this abstract entity was termed by Jacques Monod 'the postulate of objectivity', where objective meant without man, as distinct from the subjectively human. It was perhaps best explained by Ernst Mach:

If the historical sciences have inaugurated wide extensions of view by presenting to us the thoughts of new and strange people, the physical sciences in a certain sense do this in a still greater degree. In making man disappear in the All, in annihilating him, so to speak, they force him to take an unprejudiced position without himself, and to form his judgments by a different standard from that of the petty human.

Holding strong convictions one naturally liked seeing them transcend petty humanity- beyond human doubt and frailty. When last century Mach's countrymen took the annihilating a bit more literally it impressed with horrifying impact the perils of dehumanizing science. The idea of absolute and objective truth generated also absolute and objective 'laws', which abound in some branches of knowledge, and serve perhaps to remind us of Tolstoy's saying that where there is law there is injustice. The brunt of the endeavor and the aim of science was the discovery of facts, axioms, and phenomena that had existence independent of man, while at the same breath conceding that it was man doing all this.

It is now generally recognized that human psychological and social factors influence man's perception of reality. In order, therefore, to fathom the validity of assertions concerning 'true facts' one must allow for the psychological state of those asserting them, and the social context-of the society of scientists and society at large-in which the assertions were made. The innocent belief in true reality independent of man has been recently amended to include man; namely, a society of experts. A true physical fact is now often understood to mean a state of affairs that appears in only one particular way to the largest number of interested observers, a process named by Michael Polanyi 'mutual authority', and by John Ziman 'maximal consensuality', the democratic rule by jury and consensus. Not everyone is interested, say, in Cosmology; if one has a question in cosmology one accepts as true answers given by men interested in the subject, and their knowledge in turn was largely formed by absorbing the knowledge of their similarly minded (interested) ancestors and contemporaries. The ill side-effects of specialization that often ensue are well known, and may simply be based on normal adaptation-breathing the same air long enough, one cannot smell it anymore.

The concept of consensuality is nevertheless useful, provided we remember cases like that of Ren Blondlot's fantastic N-rays, (accepted by mutual consensus of French authorities), and not forget Francis Bacon's words: "Anticipations [theories] are a ground sufficiently firm for consent; for even if men went mad all after the same fashion, they might agree one with another well enough."

We need not here dwell on this very large topic once named Epistemology, and now Cognitive Science; the point is that truth, including scientific truth, is a relative phenomenon: what was true yesterday is false today, true to one false to others. The validity of a new truth will therefore generally depend on how many people are at that moment ready to accept it, and this depends largely on how many are pleased by it-either by the emotional comfort it provides, by its rational elegance, or by its practical utility to society.

When almost all perceive an event in only one particular way it attains almost absolute certainty. A heated wire emits lights, everyone can see it-it is true reality-except in a society of the blind, but then this society itself is not a true representation of mankind. A true fact of perception is, therefore, related to the established view of man's physiological normalcy. And finally, since realistic concepts can be formed only on the basis of some perceived information, it follows that the veracity of a concept depends on its affinity to truly perceived data. We may, of course, form concepts- like heaven and hell-that are not based on perceived data, but then their validity can ill be proven and is justly in doubt. In order for a physical fact to be accepted as true it ought to be perceived as nearly as possible independently of the position where the fact was observed-what is true in New York must be true also in Moscow. True facts of nature ought also be independent of time: the heating effect of fire must have been as true to prehistoric man as it is to us. The assumption is that man's physiology and his perceptual mechanisms did not materially change over time. Therefore, all true facts are reproducible in different places at different times.

SPACE

Newer advances in understanding the human body and its various functions-particularly in cognitive neurophysiology and developmental psychology - underpin the apparent fact that human cognition is based on neuronal activities. This understanding altered the view, first developed by Immanuel Kant (1724-1804), which saw cognition founded upon certain transcendental concepts beyond human experience. It now appears that knowledge that we are conscious of-as a form of information storage-resides in the cerebral cortex, whereto it arrived by means of nerves from special sensory endorgans and other parts of the body; other knowledge arrives to subcortical centers and remains largely subconscious, whence it may be retrieved, as Freud showed, by an arduous act of search and analysis. This neuronal activity of information retrieval and storage begins in utero before birth, as evidenced, for instance, by the embryo's reactions to sound. The term 'knowledge' does not here include rudimentary automatic activities, such as metabolism, which evolved by genetic transmission of chemical compounds.

Aside from data perceived through specific sense organs, the brain is fed propioceptive information about the position of the body and its extremities. Propioception is very primitive, remains mostly subconscious, and starts before specialized sense organs attain their proper function. It is prerequisite to normal muscular activity, for in order to activate a muscle, information must be available about its state of contraction or relaxation, and the state of contraction of its antagonistic muscle. At the time of birth man thus already possesses information, first about his own body, concerning positions in space - three-dimensional space.

The concept we form of three-dimensional space, based on perceived sensory data, is present at birth and yet is not transcendental; namely, it is not an essential feature that must necessarily be accepted a priori when talking of man and his world. Practically though, no human-being has yet been described who lacked-consciously or subconsciously-a concept of three-dimensional space:

Biological and psychological research combine to confirm the conclusion that, as regards the intuition of space, the nativistic view can all the more be maintained. The chick has scarcely broken from its shell than it is seen to be at home in space and pecking at everything that excites its attention.

Saying that three-dimensional space is 'common-sense' and 'common experience' means that the largest possible consensus, a consensus formed by all mankind, perceives it in only one way. This perception of space is augmented after birth by specific information gained through the sense organs-such as the visual perception of nearness and distance, left and right, up and down-information closely tied to that received from the semi-circular canals situated in the inner ear on three different planes, corresponding to the three dimensions. This development of spacial perception after birth had been thoroughly studied by Jean Piaget and his school.

Accepting man a priori, and recognizing that he arrives in this world with a concept of three-dimensional space, it is yet necessary to describe this space. The prerequisite task of exploring space with the intent of discovering or arranging in it a rational system is based on the need to understand events in it. We need a systematic order amenable to human perception and easy conception which will aid orientation in space prior to taking action in it. In empty space we know not where we are-nor whether we are coming or going- but with some order we can find our way and then march on.

Given space and the task of instilling some order in it, we begin with the smallest conceivable building block within space. For a definition to be widely applicable it must consist of a minimum number of new terms; the aim is to define and explain the maximum number of entities and events by the least number of entities that are beyond definition and comprehension. In addition, a strictly valid definition cannot include the term to be defined, or at least ought to admit as little of it as possible.

The smallest amount of space is termed 'a point'. When we say 'a' we mean 'one' and imply that we know that it differs from 'two' or any other number. A point is said to have no dimensions-no length, width or depth-and may thus seem a purely imaginary abstract concept. Inasmuch though as any image, any concept, is based on some perception, the dimensions of a point are related to the size of the space under discussion. In the All of the universe a point may have the dimensions of the sun, while within the space of a molecule a subatomic particle may be seen as a point; every point marked on paper has real three dimensions, albeit very small. James Clerk Maxwell named it 'A material particle: A body so small that, for the purposes of our investigation, the distances between its different parts may be neglected.' The concept of the point, as the first step on the way towards rationality, stands at the beginning of geometry and other systematic knowledge, and was thus no small feat of the human intellect.

A single point in space does not establish any order, and, therefore, we introduce another point. We term the space between the two points 'a line', or 'unidimensional'. The smallest amount of space between two points is given when they are adjacent to one another, and this space we term 'a straight line'.

(Continues...)

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