Luminiferous Aether -- Curt Weinstein, 2/25/2014
Question: As the Sun travels through the galaxy dragging the Earth, the Earth, spinning on its axis, revolves around the Sun. On the Earth, I watch as a barometer drops off the roof of a building. My professor asks me, “Which direction did it fall?”
References:
1. http://en.wikipedia.org/wiki/Luminiferous_aether (3-Feb-2014)
2. http://www.ifi.unicamp.br/~assis/Weber-Kohlrausch(2003).pdf (4-Feb-2014)
3. http://en.wikipedia.org/wiki/Lorentz_ether_theory (6-Feb-2014)
4. https://sites.google.com/site/lettertodrhowardspivak/ (2013)
5. http://relativelynot.weebly.com (2014)
6. Beckmann, Petr Einstein Plus Two (1987) The Golem Press, Boulder, Colorado (found 2013)
7. http://www.victorianweb.org/science/ether.htm (2014)
8. Licer, Matjaz The Concept of Aether in Classical Electrodynamics and Einstein’s Relativity. Filozofski vestnik, Volume 34 (2), 2013, pp 61-77 (as posted on 2-24-14)
Answer: Contemplating the complex movements of the Sun and the Earth within the galaxy, I answer, “down.” Thank you, Neils Bohr.
Aether is the stuff that light needs to be transmitted from here to there. Somewhat similarly, air is the stuff that sound needs to be transmitted from here to there. Of course, sound or light could use traverse through water. Conceptually, however, as sound needs air, light needs aether. In the seventeenth century, Huygens had conceived of aether as a gas that permeated space. Of course, if light were conceived as a particle (e.g., a pebble) it wouldn’t need an aether. Empty space would do.
Nevertheless, Robert Boyle used an aether concept, even before Isaac Newton, to explain interactions between masses and the like, such as magnetism and
gravity.
Huygens had guessed the wave-nature of light and had hypothesized an aether. Both Huygens and Newton could imagine longitudinal waves for light. Longitudinal waves, however, did not allow birefringence, the differential reflection of waves by a crystal. (Birefringence is now explained by the polarization of transverse waves.) Although Newton had used a particle (corpuscle) theory of light to explain reflection, that conception did not work with refraction or diffraction, and Newton knew that. In his Opticks (1704), therefore, Newton brought forward a concept of an
aether that would transmit vibrations faster than light.
Nevertheless, Newton was uncomfortable with an all pervasive aether, if for no other reason that this aether did not retard the motions of the planets. Of course, we could ask the opposite – what if the aether facilitated the motion of planets? For instance,
gravity facilitates the motion of planets
(around the sun).
Bradley, about 1720, experimented with star light in his efforts trying to find parallax. Even though he didn’t detect stellar parallax, he did detect stellar aberration. Please note, parallax depends on the positions of the observer and the objects observed, whereas, aberration depends on their relative motion. Noticing that the position of a star changed with the seasons (i.e., as the Earth orbited the Sun), Bradley couched his explanation in Newton’s particle theory of light.
Thus, he showed that vector addition of
the velocities of Earth and star light
explained the aberration angle (i.e., stellar aberration).
Let me explain the aberration of (star) light by making an analogy to the aberration of rain. Conceptually, a star’s angle of aberration is similar to a raindrops’ angle of aberration. The raindrops are falling vertically to Earth, but you are walking. Thus, you observe an angle to the falling raindrops. Walking through rain mirrors the concept of stellar aberration. Let me restate this. When you are standing still in vertical rain, the rain misses your face; when you walk, the rain hits your face. The vector addition of walking and raining explains your wet face. This shows how rain aberration models stellar aberration.
Bradley used the Earth’s velocity (relative to the sun) and the aberration angle of star light to calculate the speed of light. Nevertheless, Bradley rejected the aether theory. Just as Newton rejected the wave model of light and, hence, the aether theory that it implied, Bradley also rejected the aether theory. The prevailing concept of aether presented problems. Explaining stellar aberration, at that time, “required” that the aether be immobile in space, and, thus, the prevailing idea was the Earth moves through the aether. Just as mechanical waves needed a medium for propagation, scientists had assumed that light also needed a medium for propagation. (More recently, however, Einstein’s Special Relativity did away with the medium for light.)
Young and Fresnel, however, brought back light as a wave. This time they conceived of light as a transverse wave, rather than a longitudinal wave (as sound). Transverse waves could be polarized, and polarization could explain birefringence. Scientists also thought that only waves could explain diffraction. Therefore, scientists abandoned Newton’s particle model of light. This was well before de Broglie’s concept of matter waves. De Broglie blended the concepts, giving a wavelength to a moving mass. But long ago, physicists thought that light waves needed a medium for propagation, much as mechanical waves. Thus, they believed conceptually in an aether-gas that filled space (as Huygens had proposed in an earlier century).
Perhaps, I should share my feelings about waves and particles. A particle is like a pebble. A wave is formed from a set of particles. The set may interact to give wave properties. Thus, I do not see the big difference between a water molecule (a pebble) and a tsunami (a wave) – unless approached by one or the other.
The new concept of the aether-gas came brought new problems. Because of the nature of light, it was generally believed that the aether could not be a gas (compressible, etc.), for it had to behave more as a solid to transmit light quickly. The aether, however, was conceived a solid that did not interact with matter, and conceptually, that was too strange for many. (I agree.) Augustin-Louis Cauchy had proposed a dragging (also known as an “entrainment”) of the aether (I also agree); however, that idea wasn’t popular. Cauchy also suggested that the aether had a negative compressibility. That is, the aether was compressed naturally, and a wave of light would uncompress the aether. (I don’t see any advantages of positively or negatively squeezing the aether.) Stressed concrete, in comparison to simple driveway cement, is made to act that way (negatively squeezable).
Others did not believe that model. George Green said that such a fluid would be unstable, though I am not sure why. George Gabriel Stokes, however, promoted a dragged-aether model in which the aether was solid at high frequencies but fluid at lower frequencies – a model presumably following the properties of pine pitch. Thus, the (low frequency) Earth could move through the gaseous aether, and the (high frequency) light could move through the solid aether. The model was not bad as a generalization of pine pitch. It was, however, asking for any dragged-aether model to be put to sleep. Thus, we see how the scientists of their time used the ideas of their time (stressed concrete or pine pitch) to model the universe. It seems reasonable to me that they would take such positions.
In the late nineteenth and early twentieth century, scientists were, perhaps, unduly influenced by religion. For example, one idea circulating was: if we could see things as G-d saw them, they wouldn’t be complicated for us. (I am not sure why, but it was a popular notion.) Thus, I am reminded of a researcher who, while investigating human sensitivity, was distracted by researched values of 1, 2, and 3 for the first logical three items he sought. He kept looking for the fourth item to be four. Unfortunately, there was no “4.” In the investigation of electromagnetism, perhaps a similar cognitive blindness existed. For example, in 1856 Weber and Kohlrausch performed an experiment in which the result was found to be equal to the speed of light times the square root of two. Although they became excited, perhaps they shouldn’t have been – unless they had a good reason for the square root of two. After all, we could just as easily ask, “Why not the speed of light times 1.7 [10^-8]?” After all, what’s so special about the square root of two?
I digress to tell you I am not biased against the square root of two. Sometimes the square root of two is relevant! Recently a researcher (in another field) calculated a distance that was about 1.4 (about the square root of two) times what was predicted. (“Predicted” is an important element in research.) Someone else solved the enigma; the “correct” distance was the diagonal of the square, not its side. Distances of the sides of an equilateral right triangle (from the diagonal of the square) are in this ratio, 1: 1: square root [2]. So in that case, the square-root is relevant. In that case, the figure “square” (a side of 1) should have been conceived as the figure “diamond” (with a diagonal of ~1.4). Now, let us go back to the history of the aether.
Maxwell did some inventive and clever manipulations starting with Faraday’s lines of magnetic force. Although originally he had postulated aether, he later found that he did not need the aether for his results. Meanwhile, with the aether, “…Maxwell concluded that light consists of undulations of the same medium that is the cause of electric and magnetic phenomena.”(1) I note that more recently Beckmann (6) followed this concept.
Maxwell's equations required that all electromagnetic waves in vacuum propagate at a fixed speed, c. As this can only occur in one reference frame in Newtonian physics (unlike the Special-Relativity physics of Einstein), the aether was hypothesized as the absolute frame of reference in which Maxwell's equations hold. That is, the aether must be "still" universally,
otherwise c would vary along with any variations
that might occur in its supportive medium.
(I, however, do not have a problem with a varying speed of the aether; I, however, do not have a problem with a varying speed of light; I will fill you in later, but, for example, you will accept that light slows in water.) Maxwell himself proposed several mechanical models of aether, which were shown with wheels and gears; George FitzGerald even constructed a working model of one. These models had to agree with the fact that the electromagnetic waves are transverse but never longitudinal.(1) (Nothing personal here, but “transverse” vs. “longitudinal” are not carved in stone but are mostly descriptive. Even common longitudinal – compressive – water waves show a transverse element at a surface.)
By the early 20th Century, the aether theories were in trouble again. A several experiments had been conducted in the late 19th century to detect the motion of the Earth through the aether, and all failed. While a set of aether-dragging theories could explain the null result, the theories were complex and unpalatable. (1) They tended towards the use arbitrary coefficients meeting new physical assumptions. Using the Lorentz Ether Theory, Lorentz and Fitzgerald offered an elegant solution to how an absolute aether could be undetectable. They used length contraction. Nevertheless, Einstein’s new special theory of relativity (1905) would generate the same results without the need of any aether. Thus, the theory of Lorentz and Fitzgerald was cut down by Occam's Razor.(1)
I comment again. Occam’s Razor suggests that we choose the simplest explanation, not the correct one. How do we know when the explanation is “not the simplest”? It is “not the simplest” when it fails to explain something that it should. Thus, by reapplying Occam’s razor, we are eventually led to the correct explanation. The Special Theory of Relativity, however, leads us to wrong conclusions! For example,
the aberration of star light can easily
be explained by means of an aether.
Yet, Einstein’s Special Theory of Relativity does not explain well the aberration of star light. (forgot the reference)
But where is this aether? Maxwell had finally rid himself of the aether. He had written that the aether was magical, a fluid filling space that became rigid when necessary. Further, it was massless without viscosity, and it was transparent. It was both incompressible and (almost) continuous. (1) As a youth, when I wanted to hide an object, I learned it was best to find a hiding place in plain sight. In that way, the seeker would continually overlook it, as he looked for it. The object was a chameleon, always in his sight but never in his perception. That is the best way to hide things, aether included. I comment that aether cannot be a solid and a fluid; it is probably not compressible. It is right in front of us by definition. You are looking through the aether right now, but it cannot be universally invisible. It must be detectable by light!
There’s an old joke among scientists. A scientist wins his research-group’s lottery; his reward is to present their new findings at an important scientific conference. Right before he is about to deliver their findings to the world, he receives a telegram, which reads, “Details to follow, but for now, in our paper, right before the word ‘significant,’ please insert the word ‘not’.”
At this time, I am tiring. The history of the aether is getting wearing at me. Does aether exist? Well, according to Einstein’s Special Relativity, there is no aether. Well done, Einstein! But according to Einstein’s General Theory of Relativity, there is an aether! Well done, Einstein! (He just has to be right somewhere.) There is more, much more, but I will skip most of the remaining history.
Poincaré wrote in 1889 (3):
Whether the ether exists or not matters little –
let us leave that to the metaphysicians;
what is essential for us is, that everything happens as if it existed,
and that this hypothesis is found to be suitable for the explanation of phenomena.
After all, have we any other reason for believing in the existence of material objects?
That, too, is only a convenient hypothesis;
only, it will never cease to be so, while some day,
no doubt, the ether will be thrown aside as useless.
First, the underline is my addition in the 1889-quote from Poincaré, above.
Second, the aether may seem useless, but gravity is not, and they are one.
Professor Licer (8) claims that Professor Einstein with the introduction of General Relativity created an aether out of gravity.
Therefore, the aether exists, and the aether is gravity.
Although Professor Licer yet likes the Lorentz contraction, which is used in General Relativity, I prefer the Relativistic Bernoulli Effect to explain the same phenomena. More about this later.
Question: As the Sun travels through the galaxy dragging the Earth, the Earth, spinning on its axis, revolves around the Sun. On the Earth, I watch as a barometer drops off the roof of a building. My professor asks me, “Which direction did it fall?”
References:
1. http://en.wikipedia.org/wiki/Luminiferous_aether (3-Feb-2014)
2. http://www.ifi.unicamp.br/~assis/Weber-Kohlrausch(2003).pdf (4-Feb-2014)
3. http://en.wikipedia.org/wiki/Lorentz_ether_theory (6-Feb-2014)
4. https://sites.google.com/site/lettertodrhowardspivak/ (2013)
5. http://relativelynot.weebly.com (2014)
6. Beckmann, Petr Einstein Plus Two (1987) The Golem Press, Boulder, Colorado (found 2013)
7. http://www.victorianweb.org/science/ether.htm (2014)
8. Licer, Matjaz The Concept of Aether in Classical Electrodynamics and Einstein’s Relativity. Filozofski vestnik, Volume 34 (2), 2013, pp 61-77 (as posted on 2-24-14)
Answer: Contemplating the complex movements of the Sun and the Earth within the galaxy, I answer, “down.” Thank you, Neils Bohr.
Aether is the stuff that light needs to be transmitted from here to there. Somewhat similarly, air is the stuff that sound needs to be transmitted from here to there. Of course, sound or light could use traverse through water. Conceptually, however, as sound needs air, light needs aether. In the seventeenth century, Huygens had conceived of aether as a gas that permeated space. Of course, if light were conceived as a particle (e.g., a pebble) it wouldn’t need an aether. Empty space would do.
Nevertheless, Robert Boyle used an aether concept, even before Isaac Newton, to explain interactions between masses and the like, such as magnetism and
gravity.
Huygens had guessed the wave-nature of light and had hypothesized an aether. Both Huygens and Newton could imagine longitudinal waves for light. Longitudinal waves, however, did not allow birefringence, the differential reflection of waves by a crystal. (Birefringence is now explained by the polarization of transverse waves.) Although Newton had used a particle (corpuscle) theory of light to explain reflection, that conception did not work with refraction or diffraction, and Newton knew that. In his Opticks (1704), therefore, Newton brought forward a concept of an
aether that would transmit vibrations faster than light.
Nevertheless, Newton was uncomfortable with an all pervasive aether, if for no other reason that this aether did not retard the motions of the planets. Of course, we could ask the opposite – what if the aether facilitated the motion of planets? For instance,
gravity facilitates the motion of planets
(around the sun).
Bradley, about 1720, experimented with star light in his efforts trying to find parallax. Even though he didn’t detect stellar parallax, he did detect stellar aberration. Please note, parallax depends on the positions of the observer and the objects observed, whereas, aberration depends on their relative motion. Noticing that the position of a star changed with the seasons (i.e., as the Earth orbited the Sun), Bradley couched his explanation in Newton’s particle theory of light.
Thus, he showed that vector addition of
the velocities of Earth and star light
explained the aberration angle (i.e., stellar aberration).
Let me explain the aberration of (star) light by making an analogy to the aberration of rain. Conceptually, a star’s angle of aberration is similar to a raindrops’ angle of aberration. The raindrops are falling vertically to Earth, but you are walking. Thus, you observe an angle to the falling raindrops. Walking through rain mirrors the concept of stellar aberration. Let me restate this. When you are standing still in vertical rain, the rain misses your face; when you walk, the rain hits your face. The vector addition of walking and raining explains your wet face. This shows how rain aberration models stellar aberration.
Bradley used the Earth’s velocity (relative to the sun) and the aberration angle of star light to calculate the speed of light. Nevertheless, Bradley rejected the aether theory. Just as Newton rejected the wave model of light and, hence, the aether theory that it implied, Bradley also rejected the aether theory. The prevailing concept of aether presented problems. Explaining stellar aberration, at that time, “required” that the aether be immobile in space, and, thus, the prevailing idea was the Earth moves through the aether. Just as mechanical waves needed a medium for propagation, scientists had assumed that light also needed a medium for propagation. (More recently, however, Einstein’s Special Relativity did away with the medium for light.)
Young and Fresnel, however, brought back light as a wave. This time they conceived of light as a transverse wave, rather than a longitudinal wave (as sound). Transverse waves could be polarized, and polarization could explain birefringence. Scientists also thought that only waves could explain diffraction. Therefore, scientists abandoned Newton’s particle model of light. This was well before de Broglie’s concept of matter waves. De Broglie blended the concepts, giving a wavelength to a moving mass. But long ago, physicists thought that light waves needed a medium for propagation, much as mechanical waves. Thus, they believed conceptually in an aether-gas that filled space (as Huygens had proposed in an earlier century).
Perhaps, I should share my feelings about waves and particles. A particle is like a pebble. A wave is formed from a set of particles. The set may interact to give wave properties. Thus, I do not see the big difference between a water molecule (a pebble) and a tsunami (a wave) – unless approached by one or the other.
The new concept of the aether-gas came brought new problems. Because of the nature of light, it was generally believed that the aether could not be a gas (compressible, etc.), for it had to behave more as a solid to transmit light quickly. The aether, however, was conceived a solid that did not interact with matter, and conceptually, that was too strange for many. (I agree.) Augustin-Louis Cauchy had proposed a dragging (also known as an “entrainment”) of the aether (I also agree); however, that idea wasn’t popular. Cauchy also suggested that the aether had a negative compressibility. That is, the aether was compressed naturally, and a wave of light would uncompress the aether. (I don’t see any advantages of positively or negatively squeezing the aether.) Stressed concrete, in comparison to simple driveway cement, is made to act that way (negatively squeezable).
Others did not believe that model. George Green said that such a fluid would be unstable, though I am not sure why. George Gabriel Stokes, however, promoted a dragged-aether model in which the aether was solid at high frequencies but fluid at lower frequencies – a model presumably following the properties of pine pitch. Thus, the (low frequency) Earth could move through the gaseous aether, and the (high frequency) light could move through the solid aether. The model was not bad as a generalization of pine pitch. It was, however, asking for any dragged-aether model to be put to sleep. Thus, we see how the scientists of their time used the ideas of their time (stressed concrete or pine pitch) to model the universe. It seems reasonable to me that they would take such positions.
In the late nineteenth and early twentieth century, scientists were, perhaps, unduly influenced by religion. For example, one idea circulating was: if we could see things as G-d saw them, they wouldn’t be complicated for us. (I am not sure why, but it was a popular notion.) Thus, I am reminded of a researcher who, while investigating human sensitivity, was distracted by researched values of 1, 2, and 3 for the first logical three items he sought. He kept looking for the fourth item to be four. Unfortunately, there was no “4.” In the investigation of electromagnetism, perhaps a similar cognitive blindness existed. For example, in 1856 Weber and Kohlrausch performed an experiment in which the result was found to be equal to the speed of light times the square root of two. Although they became excited, perhaps they shouldn’t have been – unless they had a good reason for the square root of two. After all, we could just as easily ask, “Why not the speed of light times 1.7 [10^-8]?” After all, what’s so special about the square root of two?
I digress to tell you I am not biased against the square root of two. Sometimes the square root of two is relevant! Recently a researcher (in another field) calculated a distance that was about 1.4 (about the square root of two) times what was predicted. (“Predicted” is an important element in research.) Someone else solved the enigma; the “correct” distance was the diagonal of the square, not its side. Distances of the sides of an equilateral right triangle (from the diagonal of the square) are in this ratio, 1: 1: square root [2]. So in that case, the square-root is relevant. In that case, the figure “square” (a side of 1) should have been conceived as the figure “diamond” (with a diagonal of ~1.4). Now, let us go back to the history of the aether.
Maxwell did some inventive and clever manipulations starting with Faraday’s lines of magnetic force. Although originally he had postulated aether, he later found that he did not need the aether for his results. Meanwhile, with the aether, “…Maxwell concluded that light consists of undulations of the same medium that is the cause of electric and magnetic phenomena.”(1) I note that more recently Beckmann (6) followed this concept.
Maxwell's equations required that all electromagnetic waves in vacuum propagate at a fixed speed, c. As this can only occur in one reference frame in Newtonian physics (unlike the Special-Relativity physics of Einstein), the aether was hypothesized as the absolute frame of reference in which Maxwell's equations hold. That is, the aether must be "still" universally,
otherwise c would vary along with any variations
that might occur in its supportive medium.
(I, however, do not have a problem with a varying speed of the aether; I, however, do not have a problem with a varying speed of light; I will fill you in later, but, for example, you will accept that light slows in water.) Maxwell himself proposed several mechanical models of aether, which were shown with wheels and gears; George FitzGerald even constructed a working model of one. These models had to agree with the fact that the electromagnetic waves are transverse but never longitudinal.(1) (Nothing personal here, but “transverse” vs. “longitudinal” are not carved in stone but are mostly descriptive. Even common longitudinal – compressive – water waves show a transverse element at a surface.)
By the early 20th Century, the aether theories were in trouble again. A several experiments had been conducted in the late 19th century to detect the motion of the Earth through the aether, and all failed. While a set of aether-dragging theories could explain the null result, the theories were complex and unpalatable. (1) They tended towards the use arbitrary coefficients meeting new physical assumptions. Using the Lorentz Ether Theory, Lorentz and Fitzgerald offered an elegant solution to how an absolute aether could be undetectable. They used length contraction. Nevertheless, Einstein’s new special theory of relativity (1905) would generate the same results without the need of any aether. Thus, the theory of Lorentz and Fitzgerald was cut down by Occam's Razor.(1)
I comment again. Occam’s Razor suggests that we choose the simplest explanation, not the correct one. How do we know when the explanation is “not the simplest”? It is “not the simplest” when it fails to explain something that it should. Thus, by reapplying Occam’s razor, we are eventually led to the correct explanation. The Special Theory of Relativity, however, leads us to wrong conclusions! For example,
the aberration of star light can easily
be explained by means of an aether.
Yet, Einstein’s Special Theory of Relativity does not explain well the aberration of star light. (forgot the reference)
But where is this aether? Maxwell had finally rid himself of the aether. He had written that the aether was magical, a fluid filling space that became rigid when necessary. Further, it was massless without viscosity, and it was transparent. It was both incompressible and (almost) continuous. (1) As a youth, when I wanted to hide an object, I learned it was best to find a hiding place in plain sight. In that way, the seeker would continually overlook it, as he looked for it. The object was a chameleon, always in his sight but never in his perception. That is the best way to hide things, aether included. I comment that aether cannot be a solid and a fluid; it is probably not compressible. It is right in front of us by definition. You are looking through the aether right now, but it cannot be universally invisible. It must be detectable by light!
There’s an old joke among scientists. A scientist wins his research-group’s lottery; his reward is to present their new findings at an important scientific conference. Right before he is about to deliver their findings to the world, he receives a telegram, which reads, “Details to follow, but for now, in our paper, right before the word ‘significant,’ please insert the word ‘not’.”
At this time, I am tiring. The history of the aether is getting wearing at me. Does aether exist? Well, according to Einstein’s Special Relativity, there is no aether. Well done, Einstein! But according to Einstein’s General Theory of Relativity, there is an aether! Well done, Einstein! (He just has to be right somewhere.) There is more, much more, but I will skip most of the remaining history.
Poincaré wrote in 1889 (3):
Whether the ether exists or not matters little –
let us leave that to the metaphysicians;
what is essential for us is, that everything happens as if it existed,
and that this hypothesis is found to be suitable for the explanation of phenomena.
After all, have we any other reason for believing in the existence of material objects?
That, too, is only a convenient hypothesis;
only, it will never cease to be so, while some day,
no doubt, the ether will be thrown aside as useless.
First, the underline is my addition in the 1889-quote from Poincaré, above.
Second, the aether may seem useless, but gravity is not, and they are one.
Professor Licer (8) claims that Professor Einstein with the introduction of General Relativity created an aether out of gravity.
Therefore, the aether exists, and the aether is gravity.
Although Professor Licer yet likes the Lorentz contraction, which is used in General Relativity, I prefer the Relativistic Bernoulli Effect to explain the same phenomena. More about this later.