Shifting Ether: Past, Present and Future
Edy Fung, May 2024, Berlin
Today we see light as photons, as common as how human civilisation used to see light as ether. During the early 20th century, the perception of ether entered a transition period and adopted nonlinear scientific narratives. On one hand, ether theory was subverted by the emergence of Einstein’s relativity in 1905. On the other hand, ether continued to exist in Great Britain as a form of the space-filling medium for the propagation of radio technology for almost 20 years further. Although ether theory has disappeared in today’s science and inherited a populistic definition, there was not a moment in history when physicists completely rejected the idea. Uncovering how this hundred-year-old belief situated itself in modern physics, meandering one or several meanings vis-à-vis the advancement of early wireless communication, the concept of ether has persevered; perhaps it is time to optimise its scientific, technological and metaphysical legacy in a different manner.
Aether, more commonly spelled ‘ether’, was a theory which was given birth from Greek mythology. A short form for Luminiferous Ether, ether referred to the hypothesis of a medium that is carrier of light waves. The theory of ether existed from the 18th century physics up to the early 20th century superseded by relativity and quantum mechanics. The main reason that the theory became obsolete was that ether played no role in Einstein’s framework, showing that it was not necessary in the mathematical formulation in Maxwell’s equation. In comparison to how long the idea of ether has lived in history, Einstein’s foundation on quantum physics has lasted only around 100 years.
Ether has become a marginal element of theoretical physics since the early 20th century, yet this does not mean the concept lacks validity today. The scientific hypothesis of ether has foundations laid by classical physicists such as Bernoulli and Newton, which were challenged as relativity and quantum mechanics emerged. As a result, primary and secondary sources surrounding responses to ether during this transformation, including Einstein’s own account, are selected for analysis. These sources not only tackle the scientific validity of ether theory but also explore socio-political influences on paradigm shifts, such as the cultural reception of Einstein’s theory and regional variations in the progress of modern physics in the UK and Europe, resulting in non-linear narratives of ether among different scientific communities.
Ether - superseded or falsified?
The failure to detect ether in the Michelson-Morley experiment in 1887 was seen as a critical turning point in ether theory. Even so, Einstein had in fact never rejected the existence of ether and his perspective on ether evolved throughout his lifetime. He first introduced special relativity in the 1905 paper[1] and addressed the traditional concept of ether as a medium for light waves as superfluous. Later models until today are largely founded on the aftermath of relativity and hence this absence of ether. Fifteen years later, Einstein suggested that there was an advantage in looking for a “new ether” in his 1920 lecture delivered at the University of Leiden,[2] one that “determines the metrical relations in the space-time continuum”. Also in the same lecture, the concept of ether was clarified not in conflict with relativity—“according to the general theory of relativity, space without ether is unthinkable”.[3] This confirms that contrary to the mainstream misbelief relativity and ether can in fact coexist.
Other physicists such as Herbert Dingle and Ebenezer Cunningham recognised ether despite the introduction of relativity. Dingle defended ether and claimed that theory of relativity was indifferent towards the existence of an ether.[4] Cunningham, the first British physicist and proponent of relativity theory, “understood Einstein’s theory to be consistent with the existence of multiple ethers, provided that every inertial frame is associated with an ether”.[5] Arthur Eddington, known for his work in general relativity and for his observational confirmation of Einstein's theory during the solar eclipse of 1919, also never gave up embracing a new concept and more metaphorical use of ether.[6]
Einstein’s theories were revolutionary and attracted a lot of critics. Further than scientific debate, part of public controversy about Einstein was stirred up under media sensationalism and nationalistic sentiments in the 1920s. As historian of science Milena Wazeck claims, opponents of relativity used ether and radio to criticise Einstein's theory.[7] As a result, Einstein’s ideas were embedded in a larger cultural shift from the old world in which the ether was still the normative theory. Now ether has become associated with those who resisted modernity and battled against Einstein as a person at the time. I would argue that has added to the concept of ether being labelled and connotated with conservatism.
Ether became associated and kept alive as an alternative, non-physicist terminology due to the development of radio and wireless technology
Besides that ether has never fully been abolished as a physical theory, it was repurposed hugely in the development of radio and wireless technology that flourished in the late 19th and early 20th centuries. Since radio technology emerged before ether was fully questioned and withdrawn, ether was naturally the term to describe the invisible medium through which radio waves travelled. (And therefore I argue ‘luminiferous’ ether should technically be ‘radiiferous’ instead!) Eventually in the 1920s and 30s, Marconi company and the BBC were established in the setting that the public was still somewhat attached to the belief that information needed a medium to transmit. For convenience, ether became shorthand for radio in Great Britain. The engineers used ether as a reference to make explanations about radio broadcasting easier, hence the new technology more believable to the public.
Outside theoretical physics, the application of the terminology of ether by engineers played a role in changing its linguistic meaning. In the first wireless messages across the Atlantic in 1903 (two years prior to Einstein’s relativity theory) to Guglielmo Marconi, it was revealed that scientist Sir Norman Lockyer referred to them as ‘ethergram’, coined by himself.[8] The term was later justified by physicist Walter Hibbert in a form of ‘etheric telegraphy’.[9] Radio engineer John Ambrose Fleming referred to the existence of ether in his lectures ‘Waves And Ripples In Water, Air, And Aether’.[10] Internet engineer Robert Metcalfe borrowed the term and named his invention “ethernet” years later which had no connotation of wireless. As a result, ether gained multiple definitions diverging from Einstein’s interpretation and the originally intended rigour.
Last but not least, there was an association of ether with amateur groups, popular culture and marketing gadgets following the end of WWI. For example, the success of the Marconi Company was largely built on the effort of amateur groups and free labour of hobby engineers. Charles R. Gibson in the Marconi Company used the word “ether” as marketing gadgets to appeal to the public.[11] Moreover, the father of radio technology, Oliver Lodge, physicist known for his scientific work on electromagnetic radiation and a major advocate of the ether theory post-relativity, had engaged spiritualism later in his life. Lodge proposed ether as a “medium” at the same time endorsing spiritual mediumship between living and dead. I would argue that his work counteracted the credibility of ether which was criticised further as a pseudoscience.
Fig. 1 Advertisement in The Wireless World, 17 September 1930, p.5. “The Lure of Ether” was a slogan used on several occasions to sell a new portable radio set fabricated by L. McMichael, Ltd.
If ether is not needed in mathematical expressions or formulations in today’s science and remains more relevant in other realms than physics itself, it is questionable to refer to ether as a scientific theory. While there have been scattered attempts by individual physicists to integrate ether into general relativity, no theories have gained significant attention or further study. A more common approach in today’s physics is quantum field theory, which combines classical field theory (including Maxwell’s equations), special relativity, and quantum mechanics.
Conclusion
The decline of ether theory in the 20th century is closely connected to the shift from classical to modern physics. The concept of ether underwent a complex historical evolution, encompassing intellectual, cultural, and political dimensions, and adopted various connotations. Ether's interpretation has been influenced by its historical supporters. Rather than discrediting ether, physicists today prefer more successful frameworks such as quantum field theory and particle physics, which have not yet achieved scientific completeness. There is ongoing work on integrating the theory of gravity into current models, with general relativity remaining the most complete and successful theory describing gravitational interactions and spacetime. Einstein had solidly entertained in his 1920 lecture the possibility of ether in new contexts, that is perhaps to move on from electromagnetism and towards unpacking truths behind gravitational force, space-time continuum and beyond. This means that it would be most beneficial if the meaning of ether can detach from its ancient Greek and mediaeval roots as anthropomorphised light, its Newtonian perception of it as the propagation medium for electromagnetic forces, and instead make a massive shift to describe the relation of time, space and gravity. Ether needs a new interpretation and absolutely not an oblivion. Ether should be revitalised to bridge the gap between past and present science, fostering continuity and paving the way for future breakthroughs. This revival will create opportunities to connect and reconnect old and new knowledge within the increasingly compartmentalised realm of scientific research.
[1] Albert Einstein, “On The Electrodynamics Of Moving Bodies” (1905).
[2] Albert Einstein, “Ether and Theory of Relativity” in The Genesis of General Relativity (Dordrecht: Springer Netherlands) pp. 1537-1542, (Lecture Given at the University of Leiden on 5th May 1920), pp. 20-24.
[3] Ibid. The sentence continues as follows: “according to the general theory of relativity, space without ether is unthinkable”; [...] But this ether may not be thought of as endowed with the quality characteristic of ponderable media, as consisting of parts which may be tracked through time.”
[4] Jaume Navarro, “Ether and Wireless: An Old Medium into New Media” in Ether And Modernity: The Recalcitrance of an Epistemic Object in the Early Twentieth Century ed. by Jaume Navarro (Oxford: Oxford University Press, 2018), pp. 145-146.
[5] Scott A Walter, “Ether and Electrons in Relativity Theory” in Ether And Modernity: The Recalcitrance of an Epistemic Object in the Early Twentieth Century ed. by Jaume Navarro (Oxford: Oxford University Press, 2018), p. 73.
[6] Arthur Eddington, "The Nature of the Physical World" (1928).
[7] Milena Wazeck, Einstein’s Opponents: The Public Controversy about the Theory of Relativity in the 1920s. Translated by Geoffrey S. Koby, (Cambridge: Cambridge University Press, 2014), pp. xxi + 355.
[8] Notes. Nature 67 (1903), p. 250 <https://www.nature.com/articles/067250a0.pdf> [accessed 23 May 2024].
[9] Jaume Navarro, p.133.
[10] John Ambrose Fleming, “Waves and Ripples in Water, Air, and Aether: Being a Course of Christmas Lectures Delivered at the Royal Institution of Great Britain.” Society for promoting Christian knowledge, 1902.
[11] Jaume Navarro, pp.138-140.