Now, although, in the earlier tutorial sections, we have introduced an electrodynamic basis for a force law that has the form needed to conform with the force of gravity, to set the stage for building a full picture of how gravity comes about, we need to believe that there is, in fact, an aether filling all space. Your physics teachers will tell you that the aether is a myth, an imaginary medium that passed away with the demise of the physicists of the 19th century.
They will tell you about the Michelson-Morley experiment and explain that it proved that light travels as fast one way, as in the opposite direction, through the space enclosed in laboratories on body Earth. It was intended to detect the Earth's motion through space, but gave a null result. This, they will argue, assures us all that the vacuum medium, the so-called 'aether' which supposedly regulates the finite speed of light, must, if it exists at all, be dragged along with body Earth. Yet, they will say, "If this is so, how does that traveling aether move through enveloping aether? The aether hypothesis presupposes a vacuum medium at absolute rest, not one which can break up so as to move with moving matter!"
Accordingly, the logical conclusion they chose to adopt was that there is, in fact, no aether at all. You are not therefore introduced to the subject, but may instead be told about Einstein's four-space. If you have progressed in studying that subject and you think you understand something about physics as a result, then you are taking too much on trust and probably lack what is needed to proceed much further with these tutorials. If on the other hand you are perplexed by Einstein's ideas and are willing to face up to the realities of the physical underworld, with its unsolved mysteries, then you will find what follows interesting.
In this tutorial I plan to deal with the issue raised by the Michelson-Morley experiment and will assume that you have read a little about the way the experiment was performed. However, can I assume that you have read, or been told by your physics teacher, about 'Fresnel drag'? One cannot dismiss 'aether drag' without first exploring how Fresnel drag gets into the act.
You see, I do not, and never did, assume that the aether had to be something at absolute rest on a universal scale. To me the aether is 'that unseen something that can store energy and affect light propagation but yet fills any free space in and around the protons and electrons and their derivative particles that we do see as the matter form'. I do not think that this definition of mine will change your teacher's opinion on the aether question, but I am sure that the aether he or she has rejected is that one said to be at absolute rest.
So what is Fresnel drag? Well, if you measure the speed of light in a block of glass or in a tank of water the speed is reduced below that applicable in the vacuum, reduced by a factor we call the refractive index. That you will know. If, however, the glass or the water is itself moving through space and relative to the laboratory frame, then the speed of light in passage through that medium is affected by that speed. It is a function of the speed of the test medium and the speed of that medium relative to the laboratory frame. The experiments on this provide the formula for the drag coefficient involved and we call this the 'Fresnel drag coefficient'.
I will quote the formula for this convection of light by moving matter as given in a textbook written by Max Born. The edition of the book I refer to was published by Dover Publications, New York in 1962. It is a curious book. From pages 128 to 140 it discusses 'The convection of light by matter' and on page 136 one reads: "Now the velocity of light in a body moving at velocity v, measured relative to the absolute ether, is:
Why, you may wonder, do I regard Born's book as curious? Well, it is curious because the first half of the book tells us about the physics that belongs to the aether era and yet the book is entitled: 'Einstein's Theory of Relativity'. Only in the second half of the book does one read about Einstein's ideas. It is as if Born began writing a book about real physics, giving the aether an appropriate share of the action, but decided as the book progressed to add reference to Einstein's theory merely to keep the book in tune with modern trends. To me it is just a convenient reference to our knowledge of aether theory as it stood before Einstein's notions intruded and pushed the aether out of sight.
That coefficient denoted fc is the Fresnel drag coefficient. Fresnel explained it by a theory which required the aether to adopt a different density when inside a material body. I, however, will use that coefficient in a similar, but slightly different, way to explain what was found in the Michelson-Morley experiment. There need be no matter in the space between the optical components of that experiment, but yet the aether can be affected as if its density were changed. "How?" you may ask. Well, all you have to do is to take note that 19th century physicists were puzzled by the aether because it exhibits some properties telling us it is a fluid and some telling us it is a solid. That was the perception from a time when little if anything was known about 'fluid crystals'. The displays in many pocket calculators use electrical signals and rely on the properties of a substance that, like the aether, exhibits properties characteristic of both the liquid state and the solid state as a function of electric field disturbances.
So if the apparatus of the Michelson-Morley experiment entrains effects akin to the action of electric fields, why should it not drag some of the structured solid-like (or crystalline) aether along with it, only to allow this to dissolve into fluid-like form which can flow backwards freely through the interstices of the solid portions of the aether to keep density constant and, indeed, avoid setting up any linear aether momentum.
I interject here the comment that my onward research into this subject tracks evidence of the aether being able to exhibit rotational momentum, angular momentum, inasmuch as a sphere of something having a mass density can spin about a central axis and not disturb enveloping aether. Such is the vista that opens provided we keep faith with the aether belief and do not allow our minds to be usurped by Einstein doctrines.
Now, we next come to some analysis to prove what I say about that Fresnel drag coefficient being relevant to the aether and the interpretation of the null finding in the Michelson-Morley Experiment.
You can, if you prefer, look up accessible references in your university library to see that the analysis is duly recorded in the annals of science. One is in 'Physics Education', v. 10, p. 327; 1975, the periodical for physics teachers published by the U.K. Institute of Physics [1975c]. Another is at p. 263-264 of v. 15 (1976) in International Journal of Theoretical Physics; abstract reference in these Web pages [1976a]. Alternatively see the author's article 'THE ETHER - AN ASSESSMENT', pp. 37-39 October 1982 issue of Wireless World; abstract reference in these Web pages [1982a].
I quote now from the first of these three references:
"The Elusive Ether
A T Jackson writing about the detection of the ether (Physics Education 1974, v. 9, p. 265) said that 'the most important fallacy in Fresnel's drift theory would seem to be that he assumed the moving medium dragged both the light and the ether along with it, although the existence of the ether had not been established'. Yet Fresnel's formula was verified by Fizeau and it was Michelson and Morley who assumed that the ether did not move with the earth and then were surprised to find that the earth's motion through the ether defied detection.
The very astute student may question why Fresnel's analysis involved a fallacy. If the role of the ether in controlling light propagation is analogous to the role of a substance in transmitting sound, the propagation velocity c1 is proportional to (P/ρ)1/2, where P is a pressure modulus and ρ is density. Since the speed of light is fixed at c and refractive index n is c/c1, we then find that n2 is proportional to ρ. Now, Fresnel said that the velocity of light would be increased by u(1-1/n2) due to motion of a disturbing medium at velocity u. If then the ether has structure and its bulk has density ρk that moves as a disturbance at velocity u, we may write:
n2 = 1 - k uk + v(1 - k) = 0because n equals 1 when k equals zero and the ether exerts no linear force on matter, meaning that its momentum is conserved as k varies.
It is then a simple matter of algebra to show that u(1-1/n2) is simply v. This means that the velocity of light relative to the earth frame is constant, as Michelson and Morley found."
I end this tutorial by declaring that I find it absolutely incredible that those who teach physics have failed to take note of this very clear message that an aether having the properties of a fluid crystal medium must, on the basis of historical experiments on light convection in moving media, exhibit the null effect observed in the Michelson-Morley experiment. It defies all logic for physics teachers to quote the Michelson-Morley experiment as evidence disproving the existence of the aether when all it did show was that the speed of light is affected by the motion of that medium through which it is propagated.
I see no discussion in the textbooks of the fact that the light rays in the experiment were not propagating freely through empty space, as was assumed. Those rays were encountering full frontal collision with their own reflection from mirrors, meaning that the energy they conveyed had to struggle to penetrate through the energy associated with those reflected waves. The null result of the Michelson-Morley experiment should never have been regarded as a sufficient reason to abolish belief in the existence of an aether. At best it proved that some preconceived notions about the aether were false but the aether cannot be eliminated because a few physicists had some false ideas!
Read on in the tutorials which follow and see what has been missed by following false doctrine and, if you, the reader, are a physics student, do press your teachers to tell you why the Fresnel drag coefficient is not applied by them to explain the null result of that famous Michelson-Morley experiment.