Aether

The aether (aka: ether) was banished from scientific discourse between about 1862 (Maxwell equations) and 1915 (theories of special and general relativity), it is thus mostly absent from the past 100 years of scientific literature. However, a quick search of the www will return numerous entries on the topic and as always, with any subject, the quality of reviews varies greatly. As a working physical theory, aether has always been categorized as metaphysics due to lack of supporting empirical evidence, but this fact shows a limitation of scientific method more than a limitation of aether theory, as scientific method has also hitherto been unable to provide empirical evidence of consciousness, yet we gladly continue to intuit our conscious selves as necessarily real phenomena. The aether is not a mystical or psudo-scientific idea, though many accounts do unbashfully waddle into utter nonsense. The interested reader may choose to review the history of aether theories compiled by E. Whittaker (1910)(1).

Due largely to suppression of the idea during the past century, the current academic climate surrounding theories of physical aether is gloomy, ignorant and denying. There are however, bright spots in the filed, if one views with an open and keen philosophical mind. Interestingly, aether theories have enjoyed a bit of a revival during the past decade, though theorists are generally careful not to use the word aether.

MINOLTA DIGITAL CAMERA
Fay Dowker has recently given a lecture at the Perimiter Institute for Fundamental Physics, entitled “Spacetime Atoms and the Unity of Physics”(2), in which she argues for an atomic (particle) foundation of physical spacetime.

frank_wilczek
Frank Wilczek has lectured at MIT in promotion of his work “The Lightness of Being: Mass, Ether, and the Unification of Forces: Anticipating a New Golden Age”(3), in which he directly promotes aether theories as “dominant in physics”.

I have lost count of the instances in which I have been told “don’t look for meaning, just do the math and you’ll get the right answer”. Considering the number of guesses, assumptions, approximations, probabilities, truncations, transformations and outright unknown sources of error in the experimental and theoretical data used to support physical theories, blind computation seems drastically insufficient at worst, and bravely heuristic at best.

Current theories work quite well to explain many physical phenomena, and indeed physicists are able to use them to plan and produce new products. However, research and development is not at the heart of physics, rather, its central purpose is basic research; a deep philosophical truth-seeking about the world around us.

In what follows we shall poke about in the philosophy of measurement, showing why science is unable to cope with aether, then focus on the reasoning that necessitates the aether as a unifying substance of physical reality.

Space, time and mass
Meters (m), seconds (s) and kilograms (kg) are units of measure used to quantify space, time and mass, respectively. The units are arbitrary, so one may just as rightly use the Fother(4), Truti(5), and Slug(6). But what does one actually measure when measuring a cubic meter, second, or kilogram? (i.e. What is space? What is time? What is mass?).

If one measures 1 m3 of ocean, then one has defined a volume of sea-water, but is it possible to measure the space itself? Does space exist discretely? If it does not, then what is vacuum?(7)

If one measures the duration needed to walk one step, one will have defined how long it takes to make a step (~ 1 s), but is it possible to measure the duration itself? Does time exist discretely? If it does not, then what is time dilation?(8)

Some day a similar argument may be made for 1 kg of cheese-cake. However, because so little is understood about mass, asking the question does mass exist discretely? seems thoroughly nonsensical. But is it really any more nonsensical than assuming that time or space may be measured? I would say that it is not, meter sticks do not measure space and clocks do not measure time, they are simply used to mark a relationship between two things or periods.

Spacetime is a complex theoretical model comprising illusory, emergent phenomena. Matter is also a complex model, and though we do not understand what mass is, we do know that there is very much more space in matter than there are mass holding particles.
– see episode 2 A Spot of Bother, earlier in this series for an account of this.

When one begins to read quantum physics (the behavior and properties of fundamental physical quanta), the subject makes very little sense. The bewilderment continues and deepens, so that even after several years of focused study one is invariably faced with contradiction, ambiguity and confusion.
– three attributes which a hard science should not possess.

Feynman
Richard Feynman
“I think I can safely say that no one understands quantum mechanics.”

Classical Balls
So, what is real – fundamentally? Newton’s works, generally known as classical mechanics, give an impression of determinism; the universe as clockwork. The mechanics of a dynamic object such as a cannon ball can be modeled mathematically; if one has knowledge (to some defined degree of accuracy) of the conditions at the beginning of flight (initial position and mass of the projectile, its velocity once fired, flight trajectory, drag due to atmospheric conditions – change in trajectory due to wind direction and wind speed… the more variables the better), then one can predict future or past conditions (to the same or a lesser degree of accuracy) at any arbitrary point along the flight, including the destination at the end of the flight (impact site, damage inflicted upon Froggy chateau, etc…). And critically for science, all of these factors are clearly verifiable by observation because their dimensions are measurable (determinable) with a level of error that is much less than the dimension of the cannon ball itself.

In the mechanics of quanta, that degree of accuracy in determination of any single variable is impossible (even in principle), and to make things worse, the more accurately one is able to determine any individual variable, the less one can know about any other.

If the error inherent in the measurement of cannon balls was nearly 100%, then one could only ever determine aspects of cannon balls with less than 100% accuracy, even if one was very clever. Also, if one had determined with 99% accuracy, that the cannon ball had some position (xyz), then one could not hope to know anything else about it. However, if one was really very clever, then one might devise a foxy (intentionally inaccurate) method of measurement. Now one might choose to view the position of the cannon ball with an accuracy equal to less than, say 75%, meaning that one might also measure its velocity, its trajectory, its mass, or whatever about it… though altogether only with an accuracy equal to less than 25%, giving a total of less than 100%.
Foxy
Tricky!

The Planck constant (h)
The problem of quanta ultimately stems from the work of Max Planck, published in 1900 “the energy emitted by a resonator [can] only take on discrete values”, for which he won a nobel prize(9). Max is responsible for the Planck constant, defined as the constant proportionality between the energy of a photon and the frequency of its electromagnetic wave(10).

From this Dirac (whom I view as a hero) was able to define angular frequency(11), which is a relationship between cycles per second (Hertz) and rate of rotation about an axis.

Dirac was a fascinating character, who contributed a great deal to the field of quantum physics during its early development. What made him particularly enigmatic was how he arrived at his various theoretical discoveries. Dirac was convinced that mathematics had to posses beauty, the more beauty there is in the mathematics, the more truth there is likely to be in it also.

Dirac
Paul Dirac

“Relativity, in spite of [the] revolutionary change which it introduced into well-established scientific ideas, was soon accepted by physicists. There are two reasons for this: (a) it is in agreement with experiment, and (b) there is a beautiful mathematical theory underlying it, which gives it a strong emotional appeal. The second reason is not so much talked about, but in my opinion it is the stronger one.

With all the violent changes to which physical theory is subjected in modern times, there is just one rock which weathers every storm, to which one can always hold fast – the assumption that the fundamental laws of nature correspond to a beautiful mathematical theory. This means a theory based on simple mathematical concepts that fit together in an elegant way, so that one has pleasure in working with it. So when a theoretical physicist has found such a theory, people put great confidence in it. If a discrepancy should turn up between the predictions of such a theory and an experimental result, one’s first reaction would be to suspect experimental error, and only after exhaustive experimental checks would one accept the view that one must look for a theory with a still more beautiful mathematical basis.”(12a)

Dirac was generally considered a strange fellow, he was painfully introverted and displayed a great economy with words, preferring to say nothing rather than drivel-on about it. More troubling for his peers however, was his ability to snatch mathematical terms from thin air when no options were available, as if he was just making stuff up; imagine Shakespeare or Van Gogh as a physicist.

“The unattainability of the perfect vacuum is all that survives of the old conflict between the aether and relativity. There does not seem to be any objection to the aether on experimental grounds, but it does require a considerable alteration of the mathematical methods used by physicists working in quantum field theory, who will no longer be able to take the vacuum as a theoretical starting point. […] It is only the failure of the world’s physicists to find [a satisfactory and complete physical theory], after many years of intensive research, that leads me to think that the aetherless basis of physical theory may have reached the end of its capabilities and to see in the aether a new hope for the future.”(12b)

Even though the new physics seemed (and still does seem) nonsensical, confusing and unrealistic, a set of equations and concepts was eventually rendered:
The fundamental particles, their interactions and the forces or phenomena produced by their interactions (i.e. the standard model of particle physics). It was this that I was studying when I envisioned the aether, though I had yet to discover the deep history of aether theories.

An Ideal Rubber Sheet
The easiest way I know of depicting my vision is by analogy of a rubber sheet. It’s a good analogy to aether and is often used to describe the effect of a massive body upon spacetime.
Spacetime_curvature
2D representation of spacetime curvature

Imagine an ideal rubber sheet, stretched perfectly flat and level. If you were to place a golf ball on the sheet, it would create a slight indent on the surface of the sheet – the golf ball would create a slight distortion due to its mass, by imposing a curvature on the plane of the sheet. If you were to add some inertial energy to the golf ball, by giving it a push, then the ball would roll in a straight line along the sheet, imposing the same scale of curved distortion on the elastic sheet as it rolled along. Now remove the golf ball and place a cannon ball on the sheet. The situation is identical as before, except that the cannon ball has a larger mass and thus imposes a greater curved deformation on the plane of the sheet. Now, with the cannon ball in situ, replace the golf ball and again give it a push. This time there are two factors acting on the motion of the golf ball, the energy you have given it and the deformation of the rubber sheet due to the mass of that cannon ball. Technically, the golf ball is rolling in a straight line, only now the plane on which it is rolling is distorted (the space is curved), so the ball appears to travel in an elliptical trajectory, thus orbiting the cannon ball.

Critically, the observed change in behavior of the golf ball could not happen if there were no rubber sheet, which acts both as space and medium (mediating the interaction between the golf ball and cannon ball). The golf ball’s elliptical path about the cannon ball is due to a direct interaction between the mass of the cannon ball and the material from which the sheet is composed, not between the two massive bodies (i.e. the rubber sheet mediates the interaction between the two massive bodies).

http://xkcd.com/1158/

Simply put, general relativity defines gravitation as the curvature of spacetime due to the influence of a mass. So gravitation is the result of an interaction between a mass and the material of which spacetime is composed. Spacetime curvature produces some spectacular, observable phenomena to prove this fact, such as gravitational lensing(13).
Einstein-Ring-gravitational-lensing
An Einstein ring – example of gravitational lensing

Relativity theory forces us to assume that spaceitme is a physical material capable of mediating physical forces. As such spacetime must comprise measurable physical properties. Silly as this might seem, what we would have measured (above) is sillier still; one cubic meter of nothing, happening for an arbitrary period of time. Nothing can not have physical properties, it quite simply is not there. More interesting still, vacuum (free space) does not in fact ever exist: “[Vacuum] contains vacuum fluctuations (virtual particles that hop into and out of existence), and a finite energy called vacuum energy. Vacuum fluctuations are an essential and ubiquitous part of quantum field theory. Some experimentally verified effects of vacuum fluctuations include spontaneous emission, the Casimir effect and the Lamb shift”.(14)

It would appear that the units of measurement for both space and time are fundamentally wonky. The length of one meter is dependent on light traveling in a vacuum, though the latter can never exist, and a period of one second is dependent on light traveling in a vacuum and an accurate meter stick!

Rabbit hole anyone?

Clearly the fundamental issues surrounding and defining spacetime are contradictory, ambiguous, and certainly confusing! However, space does display physical properties: a special kind of resistance and conductance, termed permittivity(15) and permeability(16).

Long before Relativity, Newton intuited a particle that he called the fluxion, which was to mediate the gravitational force. He rejected the assumption that interstellar space was a vacuum, preferring instead to regard it as material composed of fluxions.
Isaac_Newton
Isaac Newton

In correspondence with Richard Bentley, Master of Trinity College, Newton is documented as having said: “That gravity should be innate, inherent and essential to matter so that one body may act upon another at a distance through a vacuum without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity that, I believe, no man who has in philosophic matters a competent faculty of thinking could ever fall into it.”(17)

Simply because space is capable of interaction, something must be out there (and in here) to do the interacting, thus space can not be nothing; space (even vacuum) is not the lack of stuff, rather it must be full of stuff. Space is made up of virtual particles (before I knew of Newton’s fluxions I coined the term spacion) to describe a very similar idea; particles that exist below the Planck constant (below the scale of Planck space, time, energy) and mediate gravitation. On occasion though, spacions do pop up above the Planck threshold as virtual particles(18) thus supporting the aether theory.

Imagine virtual particles as almost there, almost interacting. On a grand scale, you might envision a vast, omnipotent and omnipresent rolling sea of interacting waves, reaching out in all directions; but mostly not there, mostly not happening; that is spacetime (aka: aether, Tao, God).

Notes on a Theory of Quantum Gravity
A theory of quantum gravity (QG) must describe the ubiquitous, albeit uncertain, spaciotemporal action of quantum particles (gravitons) at the Planck scale (10-35 m, 10-44 s and 1019 GeV), as well as take into account Newtonian attraction and Einstein’s relativistic spacetime curvature. Gravitons must possess zero charge and zero mass and interact with all other quantum paticles.

Gravitation as a force is not felt by quanta but by large aggregates of particles (massive objects) in the absence of other forces. At the scale of fundamental particles such as gluons, quarks and atoms, reaching down from 10-12 m, the gravitational force is negligible, being about 1043 times weaker than the electrical (Coulomb) force.

Because spacetime is affected (curved) by gravitation, it too should have a fundamental quantum particle (the spacion) with which gravitons may interact. Presumably, spacions would have zero energy as well as zero charge and zero mass, and as this leaves nothing for gravitons to interact with, our current model of physical reality must have a mostly missing ingredient. Might the energy-time uncertainty principle point in this direction, allowing for an equilibrium of random vacillations between mass-energy-charge particles, which are spontaneously and temporarily (within the bounds of Planck time) created and/or extinguished?

The idea that spacions would exist only fleetingly and that their existence would necessarily be uncertain and below the extreme low end of the time-energy scale of the current model of quantum interactions, correlates with the predicted infra-weak force of quantum gravitation. The observation that only large aggregates of particles feel gravity fits this idea too, as a gravitational force field would require a vast quantity of these mostly missing (spacion) particles in order to act as a medium with which radiant mass-energy might interact.

Bibliography:
1) http://archive.org/details/historyoftheorie00whitrich
2) F. Dowker, “Spacetime Atoms and the Unity of Physics”, (2011), Perimeter Institute, http://www.youtube.com/watch?v=VhHE86d-Th8
3) F. Wilczek, “The Lightness of Being: Mass, Ether, and the Unification of Forces: Anticipating a New Golden Age”, (circa 2005), lecture video, MIT, http://mit.tv/wDym6k
4) http://en.wikipedia.org/wiki/Fother
5) https://en.wikipedia.org/wiki/Hindu_time_units#Small_units_of_time_used_in_the_Vedas
6) http://en.wikipedia.org/wiki/Slug_%28mass%29
7) https://en.wikipedia.org/wiki/Vacuum
8) https://en.wikipedia.org/wiki/Time_dilation
9) http://www.nobelprize.org/nobel_prizes/physics/laureates/1918/planck.html
10) https://en.wikipedia.org/wiki/Planck_constant
11) https://en.wikipedia.org/wiki/Angular_frequency
12a&b) P. Dirac, “Quantum Mechanics and the Aether”, The Scientific Monthly, Vol. 78, No. 3 (Mar., 1954), pages 142-146. (to view this article you must access the academic press – inquire at your local library).
13) https://en.wikipedia.org/wiki/Gravitational_lens
14) https://en.wikipedia.org/wiki/Vacuum
15) https://en.wikipedia.org/wiki/Permittivity
16) https://en.wikipedia.org/wiki/Vacuum_permeability
17) http://books.google.ca/books?id=gB2-Hqdx_LUC&pg=PA634&lpg=PA634#v=onepage&q&f=false
18) https://en.wikipedia.org/wiki/Vacuum_state#Virtual_particles

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