The Science and Technology Facilities Council has provided information that Science Daily has posted as an abstract of an article by Dr. Hong Sheng Zhao titled "Dark Fluid: Dark Matter And Dark Energy May Be Two Faces Of Same Coin." You can read this abstract at the web site below:
Dr Hong Sheng Zhao, of the University of St. Andrews, School of Physics and Astronomy, has shown that dark matter and its counterpart dark energy may be more closely related than was previously thought. "Both dark matter and dark energy could be two faces of the same coin." In Dr Zhao's model, dark energy and dark matter are simply different manifestations of the same thing, which he has labeled a 'dark fluid'. On the scale of galaxies, this dark fluid behaves like dark matter and on the scale of the Universe dark fluid behaves like dark energy.
Only 4% of the universe is made of known material - the other 96% is "traditionally," (if seventy years can establish a ‘tradition’ in a three thousand-year-old science) considered dark matter and dark energy. Dr. Zhao’s model is detailed enough to produce the same 3:1 ratio of dark energy to dark matter as is predicted by cosmologists.
Efforts are currently underway to hunt for dark-matter particles with the Large Hadron Collider at the European Organization for Nuclear Research in Geneva. According to Dr Zhao, these efforts could turn out to be fruitless. He said, "In this simpler picture of universe, the dark matter would be at a surprisingly low energy scale," too low to be probed by the upcoming Large Hadron Collider. Dr Zhao concluded. "No matter what dark matter and dark energy are, these two phenomena are likely not independent of each other." (Science and Technology Facilities Council. "Dark Fluid: Dark Matter And Dark Energy May Be Two Faces Of Same Coin." ScienceDaily 1 February 2008. 10 February 2008 <http://www.sciencedaily.com /releases/2008/01/080131094056.htm>.)
It is erroneous to regard the galaxies and stars as isolated in vacant space. Around and between them is dark matter and dark energy. To this the name dark fluid has been given. The dark fluid is the solitary tenant of the universe, save for that infinitesimal fraction of space which is occupied by ordinary matter. Hence arises a problem which has long engaged scientists, and is not yet completely solved: What relation subsists between the medium which fills the interstellar void and the matter that is scattered through it?
This question is as valid today as it was when it was written in 1910. The original quote is:
"It is thus erroneous to regard the heavenly bodies as isolated in vacant space; around and between them is an incessant conveyance and transformation of energy. To the vehicle of this activity the name aether has been given.
The aether is the solitary tenant of the universe, save for that infinitesimal fraction of space which is occupied by ordinary matter. Hence arises a problem which has long engaged attention, and is not yet completely solved: What relation subsists between the medium which fills the interstellar void and the condensations of matter that are scattered through it?" (Theories of Aether and Electricity, E. T. Whittaker, Longmans, Green and Co., Dublin, 1910, p.1)
The Swiss astronomer Fritz Zwicky is credited with the 1933 observation that the universe and galaxies are held together by the gravitational attraction of a huge amount of unseen material, now referred to as dark matter, dark energy and dark fluid. But, the history of the aether goes back many centuries before Zwicky. From the advent of Einstein’s Theory of Relatively to Zwicky’s observation, not quite a generation later, the aether seems to have been banned form scientific conversation, now it is back but none dare call it the aether.
Every science has its "demons." When I taught the History of Pharmacy at the U. of Cincinnati, College of Pharmacy, the dean didn’t want me to teach Alchemy. That was not the "image" that the profession wanted to project. Time for Astronomers and Physicists to face their demons, the aether. This will be a short history of the aether taken directly from the references.
Rene Descartes (b.1596 d,1650)
Descartes was a pivotal character in the study of Astronomy, not so much for the validity of his theories but because of the boldness of his ideas stimulated scientific thought in an unparalleled manner. It is indeed unfortunate that Descartes did not have access to detailed observations and data of later ages. He was the first natural philosopher to put forth the "principle that interplanetary space must be a plenum occupied by matter imperceptible to the touch but capable of serving as the vehicle of force and light." (Theories of Aether and Electricity, E. T. Whittaker, Longmans, Green and Co., Dublin, 1910, p.4)
Robert Hooke (b.1635,d.1703)
".... suggested that there might be an all-pervading ether... Here was a mechanism that might have owed something to Descartes’ idea of a circulatory ether, but that was much more in tune with the law of central attractive force that was in the thoughts of Hooke and his friends at the Royal Society."(circa 1664) (The Norton History of Astronomy and Cosmology, John North, W.W. Norton & Company, New York, 1994, p365)
John Bernoulli (b.1710, d.1790)
"Some attention must be given to a suggestive study of the aether, for which the younger John Bernoulli was in 1736 awarded the prize of the French Academy. His ideas seem to have been originally suggested by an attempt which his father, the elder John Bernoulli (b 1667, d. 1748), had made in 1701 to connect the law of refraction with the mechanical principle of the composition of forces.....
All space, according to the younger Bernoulli, is permeated by fluid aether, containing an immense number of excessively small whirlpools. The elasticity which the aether appears to possess, and in virtue of which it is able to transmit vibrations, is really due to the presence of these whirlpools; for, owing to centrifugal force, each whirlpool is continually striving to dilate, and so presses against the neighboring whirlpools.... he insists that even the elasticity of his aether shall be explicable in terms of matter and motion.
This aggregate of small vortices, or "fine-grained turbulent motion," as it came to be called a century and a half later, (Lord Kelvin’s vortex-sponge aether)....
A source of light communicates to its surroundings a disturbance which condenses the nearest whirlpools; these by condensation displace the contiguous corpuscules from their equilibrium position; and those in turn produce condensations in the whirlpools next beyond them, so that vibrations are propagated in every direction from the luminous point.....
Bernoulli explained refraction by combining these ideas with those of his father. Within the pores of ponderable bodies the whirlpools are compressed, so the centrifugal force must vary in intensity from one medium to another. Thus a corpuscle (of light) situated in the interface between two media is acted on by a greater elastic force from one medium than from the other; and by applying the triangle of forces to find the conditions of this equilibrium, the law of Snell and Decartes may be obtained....
It will be remembered that according to Descartes the velocity of light is greatest in dense media, while according to Fermat the propagation is swiftest in free aether...." (The Norton History of Astronomy and Cosmology, John North, W.W. Norton & Company, New York, p 100 - 03)
Leonhard Euler (b.1707, d.1783)
"The natural philosophers of the eighteenth century for the most part... accepted the corpuscular hypothesis (of light); but the wave-theory was not without defenders... Leonhard Euler... insisted strongly on the resemblance between light and sound; "light is in the aether the same thing as sound in air."..." (The Norton History of Astronomy and Cosmology, John North, W.W. Norton & Company, New York, p 407)
Euler shared a Paris Academy prize with Lagrange for their essays on the three-body problem of lunar motion. (Circa 1772) "Euler, in his essay, now maintained that gravitation could offer no explanation for the secular acceleration of the Moon, but that there must be some sort of etherial fluid in space, offering resistance to the motion of the Moon and Earth." (The Norton History of Astronomy and Cosmology, John North, W.W. Norton & Company, New York, P 390)
Thomas Young (b.1773, d.1829)
Augustin Fresnel (b.1788, d.1827)
"When Young and Fresnel put forward the view that the vibrations of light are performed at right angles to its direction of propagation, they at the same time pointed out that this peculiarity might be explained by making a new hypothesis regarding the nature of the luminiferous medium; namely, that it possesses the power of resisting attempts to distort its shape. It is by the possession of such a power that solid bodies are distinguished from fluids, which offer no resistance to distortion; the idea of Young an Fresnel may therefore be expressed by the simple statement, that the aether behaves as an elastic solid." (Theories of Aether and Electricity, E. T. Whittaker, Longmans, Green and Co. 1910, p137)
Joseph Boussinesq (b.1842)
"Before the electromagnetic hypothesis had attracted much attention, an elastic-solid theory in many respects preferable to the predecessors was presented to the French Academy by Joseph Boussinesq. Until this time, as we have seen, investigators had been divided into two parties, according as they attributed the optical properties of different bodies to variations in the inertia of the luminiferous medium, or to variations in the elastic properties. Boussinesq, taking up a position apart from both these schools, assumed that the aether is exactly the same in all material bodies as in interplanetary space, in regard both to inertia and to rigidity, and that the optical properties of matter are due to interaction between the aether and the material particles, as had been imagined more or less by Neumann and O’Brien. These material particles he supposed to be disseminated in the aether, in much the same way as dust-particles floating in the air...." (Theories of Aether and Electricity, E. T. Whittaker, Longmans, Green and Co. 1910, p185)
"It is to Boussinesq’s merit to have clearly asserted that all space, both within and without ponderable bodies, is occupied by one identical aether, the same everywhere both in inertia and elasticity; and that all aetheral processes are to be represented by two kinds of equations, of which one kind expresses the invariable equations of motion of the aether, while the other kind expresses the interaction between aether and matter." (Theories of Aether and Electricity, E. T. Whittaker, Longmans, Green and Co. 1910, p187)
Sir George Gabriel Stokes (b.1819, d.1903)
"The elastic-solid theory meets with one obvious difficulty at the outset. If the aether has the qualities of a solid, how is it that the planets in their orbital motions are able to journey through it at immense speeds without encountering any perceptible resistance? This objection was first satisfactorily answered by Sir George Gabriel Stokes, who remarked that such substances as pitch and shoemaker’s wax, though so rigid as to be capable of elastic vibration, are yet sufficiently plastic to permit other bodies to pass slowly through them. The aether, he suggested, may have this combination of qualities in an extreme degree, behaving like an elastic solid for vibrations so rapid as those of light, but yielding like a fluid to the much slower progressive motions of the planets." (Theories of Aether and Electricity, E. T. Whittaker, Longmans, Green and Co. 1910, p137)
So, how far have we come in understanding the aether, dark matter, dark energy or dark fluid? Not very far, I love the line from the Science Daily abstract noted above: "...however, the Universe might be absent of dark-matter particles at all. The findings of Dr Zhao are also compatible with an interpretation of the dark component as a modification of the law of gravity rather than particles or energy."
Note: Other than the Science Daily segment, all other information came from books. I purposely did not "google" any of the people or ideas listed here. There is a real thrill in checking our a ninety-eight year old book from the library, a reverence for the printed word. The card is still in this book, it was first checked our of the Public Library of Cincinnati in 1949, it was already an old book. On April 24, 1950 it was sent on loan to the Cornell University Library in Ithaca, N.Y., returned October 30, 1950.