On Why Einstein Rejected the Aether

Some background information on the aether, as well as Albert Einstein’s rejection thereof, is given in the book by Peter Galison, Einstein’s Clocks, Poincaré’s Maps, Norton, 2003, pp. 14, 15:

Einstein began his relativity paper [“On the Electrodynamics of Moving Bodies,” Annalen der Physik, vol. 17, pp. 891-921, 1905] with the claim that there was an asymmetry in the then-current interpretation of electrodynamics, an asymmetry not present in the phenomena of nature. Almost all physicists around 1905 accepted the idea that light waves–like water waves or sound waves– must be waves in something. In the case of light waves (or the oscillating electric and magnetic fields that constituted light), that something was the all-pervasive aether. Most late-nineteenth-century physicists considered the aether to be one of the great ideas of their era, and they hoped that once properly understood, intuited, and mathematized, the aether would lead science to a unified picture of phenomena from heat and light to magnetism and electricity. Yet it was the aether that gave rise to the asymmetry that Einstein rejected.

…But the aether itself could not be observed, so in Einstein’s view there was but a single observable phenomenon: coil and magnet approach, producing a current in the coil (as evidenced by the lighting of a lamp).

The above-mentioned asymmetry is illustrated in Fig. 1, but in a simpler configuration than the “current induced in a coil.” In Fig. 1, a voltage E is induced along a non-conducting rod. In (a), the rod moves to the right at a velocity v, cutting across the stationary magnetic field, B. The simple equation describing this is

E = Bv

using  MKS units (volts/meter, webers/sq. meter, and meters/second. A weber/sq. meter is also called a tesla. Various right-hand and left-hand rules are used to get the correct polarity.)

fig27-1

Fig. 1.  The two basic ways in which an electric field, E, can be induced along a non-conducting rod. (a)The rod moves to the right, cutting across the B flux lines of a stationary magnetic field, at a velocity v. (b)The magnetic flux field B moves to the left, cutting across the stationary rod at a velocity v.

In Fig. 1(b), paraphrasing the above, we have the magnetic field B moving to the left at a velocity v, cutting across the stationary rod.

In (a), the rod moves; in the politically correct jargon of 1905, one would say that the magnetic field is stationary while the rod moves with respect to the aether. In (b), we would say that the rod is stationary while the magnetic field moves with respect to the aether. This is the asymmetry that Einstein rejected because the induced electric field is the same in (a) and (b); obviously, it is the relative motion that is decisive.

Electrical engineers have always used the relative motion, of course, in calculating induced voltages. From the vantage point of 2005 rather than 1905, one might say that Einstein’s stress on relative motion was obvious. But he applied relativity as a general philosophy, ending up with Special Relativity, which destroyed earlier concepts of time and space.

My own view is that every massive object (planet, moon, sun, and so forth) has a stationary aether “atmosphere” that is held in place by gravitational attraction as depicted in Fig. 2. Therefore, there is nothing wrong with saying that the rod or wire or magnetic field moves with respect to the aether. To discover how the aether “atmosphere” varies as one proceeds along the photon paths of Fig. 2, we need a small, lightweight piece of equipment that can be carried by a space vehicle and that can measure the speed of light accurately, to within a few meters/second. But this is far more easily said than done; until it is done, the aether will remain an elusive concept.

fig25-1 (2)

Fig. 2. Two possible interpretations of light-ray behavior versus the aether. Because of gravitational attraction, the earth (US) and a very rapidly receding planet (THEM) each have aether “atmospheres.” Interplanetary space is filled with an aether “background,” shown as moving to the north, say, at some unspecified velocity. Despite the motion discontinuities between the “atmospheres” and “background,” the density (aether particles per cubic meter) remains unchanged. (a)The photon path bends when it traverses aether motion discontinuities upon leaving US, and also when arriving at THEM. (b)The photon path does not bend.It seems likely that Einstein’s rejection of the aether had much to do with his antiauthoritarian personality, as explained below.

With regard to Einstein’s schooling,  Galison p. 228: “After a first unsuccessful application, Einstein began his training at Switzerland’s (and one of Europe’s) great technical universities: the Eidgenossische Technische Hochschule (ETH) [in Zurich], founded in 1855. Certainly the ETH of 1896 [Einstein was 17] was a very different place from the Ecole Polytechnique that Poincaré had entered in the early 1870s.” As a young man of Jewish ancestry, he was unquestionably discriminated against. In 1901, p. 233, “… authorities were not about to respond … with a shower of job offers. One after another, rejections arrived, including one for the position of senior teacher, Mechanical Technical Department in the Cantonal Technikum at Burgdorf.” But, finally, p. 233, “Then came a genuine prospect of employment. The Swiss Patent Office in Bern had placed an advertisement for an opening.” Einstein worked at the Patent Office from June 1902 to October 1909 (age 30).

With regard to that personality, Galison p. 46: “Framing himself as a heretic and an outsider, Einstein scrutinized the physics of the fathers not to venerate and improve, but to displace.” P. 232: “Einstein’s relentless optimism and self-confidence, combined with a biting disregard for complacent scientific authority, shows in a myriad of letters.” P. 297: “For the young Einstein, repair held little appeal. Tearing down the old was a bracing pleasure. While Poincaré maintained the aether as crucial in his 1909 Lille address, Einstein began a talk of his own at almost exactly the same time with a specific reference to a physicist (not Poincaré) who had assessed the aether’s existence to ‘border on certainty.’ Then Einstein knocked the author’s assertion into the trash.” P. 310: “Delightedly mocking senior physicists, teachers, parents, elders, and authority figures of all kinds, happily calling himself a ‘heretic,’ proud of his dissenting approach to physics, Einstein shed the nineteenth century’s aether with an outsider’s iconoclastic pleasure.”

I think there is more to it than the above quotations from Galison. The following is entirely conjecture on my part:

In Special Relativity, Einstein postulated that the velocity of light on, say, the planet in Fig. 2 that is rapidly receding from the earth, is the same as the velocity on earth; that is, 300 million meters/second. He saw that the obvious physical explanation was that the receding planet, and the earth, and every massive structure, had an aether “atmosphere” held on by gravitational attraction. But there was no way to prove this. The Michelson-Morley experiment was not able to detect an aether. The aberration of starlight was not able to detect an aether. Einstein wisely saw that he would be bogged down in endless speculation about the aether, so he simply abandoned it. The aether was banished from his writings from 1901 on (except to denounce it). How did electromagnetic waves propagate through the vastness of the Universe? Somehow, but they did not need an aether carrier!

Gradually, the aether concept faded as nobody could prove that it existed.

 

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