Over the centuries numerous aethers have been proposed, and new ones are presented frequently.
This from Wikipedia:-
“Aether theories in physics propose the existence of a medium, the aether a space-filling substance or field, thought to be necessary as a transmission medium for the propagation of electromagnetic or gravitational forces. The assorted aether theories embody the various conceptions of this “medium” and “substance”.”
Christiaan Huygens suggested that light propagates as a succession of wavelets, but Newton thought that light was ‘corpuscular’, i.e. particulate, and his concept was generally accepted up to 1801 when Young’s double-slit experiments proved conclusively that light propagates as a wave.
Today, despite many thousands of experiments attempting to falsify Young’s result and demonstrate that light is particulate, it is an indisputable fact that it is a wave.
“The period from Newton to Maxwell saw a bewildering variety of ethers which in many cases were introduced for specific purposes, such as explaining electricity, magnetism, light, gravitation, nervous impulses, and chemical action” (1)
“Æthers were invented for the planets to swim in, to constitute electric atmospheres and magnetic effluvia, to convey sensations from one part of our bodies to another, and so on, till a space had been filled three or four times with æthers.” (2)
Of course with Young’s findings the problem of transmission resurfaced, as all such aethers had to have remarkable properties, firstly, in accordance with the requirements of the kinetic atomic theory of gases, these ‘space-filling’ mediums could not inhibit the eternal, kinetic motion of atoms through or within it, while at the same time these were required to sustain the propagation of light and to somehow allow the force of gravitation to act attractively between material bodies of any dimension.
“Following the pioneering work of Thomas Young in England and Augustin Fresnel in France, by the 1820s the corpuscular theory of light was abandoned and replaced by a theory of transverse waves. The new “luminiferous” ether pervaded the universe and, according to most physicists, had to behave like an elastic solid that – strangely – did not interact with other matter. Although it had the form of a solid, and was sometimes likened to steel, the planets and comets passed through it without noticing any resistance. Strange indeed!” (3)
However one such concept, based on the assumption that there was an absolute reference frame in the universe, a ‘stationary’ aether, was dealt a fatal blow in 1887, when Michelson and Morley’s sophisticated experiments, which were designed to prove its existence by demonstrating that the motion of the Earth through it could be detected, failed to do so.
To explain this ‘null’ result some aether proponents then introduced an ‘entrained aether’, i.e. one that moved with the Earth, but the problems with this concept, in a celestial sense, were enormous, and it was generally rejected.
Following Young’s experiments, the next important development, with respect to vacuum theory, was Clerk Maxwell’s statistical treatment of the kinetic theory of gases, his ‘Laws of Distribution of Velocities’ published in 1860, these laws were later generalised by Boltzmann and are known today as the Maxwell-Boltzmann Distribution.
When Maxwell formally postulated electromagnetic waves and identified light as being just a partof the spectrum of electro-magnetic radiation (EMR), he initially considered the possibility of an aether to sustain the transmission of such waves, but later distanced himself from this concept.
“Maxwell also introduced the concept of the electromagnetic field in comparison to force lines that Faraday described. By understanding the propagation of electromagnetism as a field emitted by active particles, Maxwell could advance his work on light. At that time, Maxwell believed that the propagation of light required a medium for the waves, dubbed the luminiferous aether.” (Wikipedia)
In 1900 Max Planck presented his solution to the “Ultra-violet Catastrophe” in that light exists in discrete quanta of energy. Later described as a ‘mass-less particle’,and named as the ‘photon’.
In 1909 in a lecture at Columbia University, Max Planck said: “In place of the so-called free ether there is now substituted the absolute vacuum, … . I believe it follows as a consequence that no physical properties can be consistently ascribed to the absolute vacuum” (4)
“Two years later Planck would suggest the notion of zero-point energy and thereby unwittingly initiate a development that led to the modern view of a quantum vacuum endowed with physical properties” (5)
The next development in this context was of course the ‘Einsteinian revolution’ at the beginning of the 20th century, with the Theories of Special, and later General Relativity.
Einstein believed, along with all scientists at the time, that the universe was, what we now now as, the ‘Milky Way’ galaxy and that the Earth’s atmosphere was finite, above which space was an absolute vacuum. And in his paper introducing Special Relativity (SRT) in 1905 he dismisses the aether stating:- “ a luminiferous ether will prove to be superfluous”, and introduced the counter-intuitive concept of ‘wave-particle duality’, suggesting that light propagates in some instances(e.g. through the vacuum of space) as a ‘particle’ and in others as a ‘wave’.
Around this time he also published a paper on Brownian Motion, a phenomenon that was accepted as experimental evidence for both the existence of atoms and for the kinetic atomic theory of gases, and the core assumption of this theory in that gases are largely composed of a vacuum and thus that the vacuum permeated all macroscopic matter.
But 15 years later in 1920, following the publication of the general theory of relativity (GRT) in 1917, Einstein, in a lecture entitled “Ether and the Theory of Relativity” he says:-
“ – we may say that according to the general theory of relativity space is endowed with physical qualities; in this sense, therefore, there exists an ether. According to the general theory of relativity space without ether is unthinkable”
Robert B. Laughlin, Nobel Laureate in Physics, later had this to say about the ether in contemporary theoretical physics:-
“It is ironic that Einstein’s most creative work, the general theory of relativity, should boil down to conceptualizing space as a medium when his original premise [in special relativity] was that no such medium existed. The word ‘ether’ has extremely negative connotations in theoretical physics because of its past association with opposition to relativity.”
“The modern concept of the vacuum of space is a relativistic ether. But we do not call it this because it is taboo.” (6)
The next important development for ‘vacuum theory’ was Rutherford’s analysis of the results of experiments carried out under his direction, which effectively obliterated Dalton’s indestructible, solid atom, suggesting that atoms instead were, by volume, composed almost entirely of a vacuum, with a tiny material nucleus and electrons orbiting around it.
The initial discovery was made by Hans Geiger and Ernest Marsden in 1909 when they performed the gold foil experiment under the direction of Rutherford, in which they fired a beam of alpha particles (helium nuclei) at layers of gold leaf only a few atoms thick.
Their results showed that around 1 in 8000 alpha particles were deflected by very large angles (over 90°), while the rest passed straight through with little or no deflection. From this, Rutherford concluded that the majority of the mass was concentrated in a minute, positively charged region (the nucleus/ central charge) surrounded by electrons. (Wikipedia}
Like most scientific models, Rutherford’s atomic model was neither perfect nor complete. According to classical, Newtonian physics, it was in fact impossible. Accelerating charged particles radiate electromagnetic waves, so an electron orbiting an atomic nucleus in theory would spiral into the nucleus as it loses energy. To fix this problem, scientists had to incorporate quantum mechanics into Rutherford’s model.
Following Rutherford’s atom and the development of Quantum Mechanics and Electrodynamics, Paul Dirac proposed a model of the vacuum as an infinite sea of particles with negative energy to explain the anomalous negative-energy quantum states predicted by the Dirac equation for relativistic electrons.
Paul Dirac wrote in 1951: “Physical knowledge has advanced much since 1905, notably by the arrival of quantum mechanics, and the situation [about the scientific plausibility of Aether] has again changed. If one examines the question in the light of present-day knowledge, one finds that the Aether is no longer ruled out by relativity, and good reasons can now be advanced for postulating an Aether. . . . . . . .We have now the velocity at all points of space-time, playing a fundamental part in electrodynamics. It is natural to regard it as the velocity of some real physical thing. Thus with the new theory of electrodynamics [vacuum filled with virtual particles] we are rather forced to have an Aether”.
“A full quantum theory of light (QED) had been developed, and one of its features was a new understanding of the vacuum, of emptiness. Where before the vacuum had been understood as pure emptiness – no matter, no light, no heat – now there was a residual hidden energy. Take away everything, cool to absolute zero in temperature, and still the vacuum remains, and it is shimmering with a special kind of light. Called the “zero-point energy of the vacuum” it seems an essential part of quantum field theory.” (Wikipedia)
So, together with a Relativistic Aether, now we encounter a “quantum aether”, and, one of the founders of quantum mechanics, Nils Bohr is describing this aether as having “vacuum energy” and “vacuum fluctuations”.
It was Richard Feynman who first suggested that the basic partial-differential equations of theoretical physics might be actually describing macroscopic motion of some infinitesimal entities he called X-ons. He suggested X-ons as the unifying concept for description of physical universe, though he did not specify their properties.
So physics today is still based upon this pure assumption of discontinuous atoms in a vacuum, but now the hypothetical vacuum has been extended to occupy the atom itself, which would reduce the actual volume of matter almost to nothing. So, having dug a substantial hole for themselves, physicists now are left with ‘filling the vacuum’ and I quote a certain Dr de Rũjula:- “As it turns out the vacuum is not empty – there is a difference between the vacuum and nothingness” “Surprisingly, of all know ‘substances’, the vacuum is the least well understood” Rather an understatement for something that has never been isolated and, even if this were possible, it could not be examined or investigated by any technological means.
In addition to these there are a great number of other aethers, below are listed just a few, all of which are purely speculative and there is no empirical evidence whatever for their ‘existence’.
Bohr’s Zero Point Energy
Dirac’s ‘Zero Point Field’
La Violette’s ‘Kinetic Aether’
Aspden’s ‘Liquid Crystal Aether’
Thornhill and Meyl’s ‘Cosmic Neutrino Background’
Tombe’s ‘Electric Dipole Sea’
Simhony’s ‘Cubic Space Lattice’
Correa’s ‘Ambipolar Aether’
Tewari’s ‘Space Vortex Theory”
But of course none of the myriad of vacuum filling alternative aethers, ‘strings’ ‘loops’, etc. etc., are remotely capable of investigation, as essentially the only method of investigating the sub-atomic dimension is by firing what are assumed to be ‘particles’ at something. And as this ’empty space’, by definition cannot react to such impulses, these are consequently unverifiable and speculative constructs.
If the vacuum and/or its constituent aethers of any description cannot be proven to exist by any empirical means and, as it is not possible to define what matter ‘is’ ultimately, then the currently accepted structures of both the sub-microscopic and the celestial dimensions are purely hypothetical, in other words they are speculative constructs based entirely upon a belief in the ‘existence’ of an all permeating vacuum and that ‘real’ matter is almost on the point of non-existence.
And ‘Belief System’ is an accurate description of the state of the science of physics today as the (incompatible) bases of modern physics, Relativity and Quantum theories, are completely dependent upon this assumption of a universally permeating vacuum.
First the vacuum is ‘proven’ to exist, extra atomically, and then it is ‘proven’ to extend down into the atom itself, then ‘space-filling’, non-material aethers are proposed to fill the vacuum, and now it is suggested that space is full of energy.
“There is no such thing as absolutely empty space. All space contains fluctuating fields and particles. Even in the emptiest space that the laws of nature permit, there are energy levels about which the energies of the fields and particles fluctuate; and these energy levels are never sharply defined” (7)
And in a later book by Frank Close “The Void” he states unequivocally that volumetrically the atom is composed of one trillionth matter, in the form of the nucleus and electrons, while the “rest is a perfect vacuum”. (8)
The facts are however that both these statements are purely speculative, and in recent decades extensive and expensive experiments attempting to reach absolute zero pressure and temperature have proved that the creation of the state of the non-existence of matter, i.e. a volume completely empty of matter, is not possible.
1 “Conceptions of Ether”, Cantor and Hodge, 1981.
2 Encyclopaedia Britannica, Maxwell (1965, vol. 2, p. 763)
3 “Empty space or ethereal plenum?” Helge Kragh, June 2013.
4 “Eight Lectures on Theoretical Physics”, Max Planck 1915, p. 119.
5 (Helge Kragh 2013).
6 “A Different Universe: Reinventing Physics from the Bottom Down”. Laughlin, Robert B. (2005). Basic Books.
7 “Nothingness”, Henning Genz, Basic Books 2001.
8 “The Void”, Frank Close, OUP, 2006