What’s in a name? - On the latest attempts to revive an Æther

Aug 28, 2026

Uploaded by Mason

The development and evolution of the “Einstein–Æther Theory” (Æ-theory) indicates that the word ether is being used again in cosmology, raising an open question about whether this æther continues earlier notions or represents a fundamentally new entity. The paper aims to clarify the nature of this new ether by tracing the late nineteenth and early twentieth century meanings and examining major twentieth-century revival attempts, with emphasis on Æ-theory.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages11

Reading Time28 min

AccessFree to download

Abstract

Introduction

Popular and professional uses of “ether”

Einstein–Æther theory and historical framing

From the many ethers to the many uses of the one ether

Eur. Phys. J. H (2023) 48 :3 [https://doi.org/10.1140/epjh/s13129-023-00054-3](https://doi.org/10.1140/epjh/s13129-023-00054-3) THE EUROPEAN PHYSICAL JOURNAL H Regular Article What’s in a name? On the latest attempts to revive an Æther Ben˜at Monfort-Urkizu1,a and Jaume Navarro2 ,b 1 University of the Basque Country (EHU/UPV), Donostia, Gipuzkoa, Spain 2 University of the Basque Country (EHU/UPV) and Ikerbasque (Basque Foundation for Research), Donostia, Gipuzkoa, Spain Received 1 November 2022 / Accepted 14 April 2023 / Published online 7 May 2023 © The Author(s) 2023 Abstract The development and evolution of the “Einstein–Æther Theory”(Æ-theory) shows that there is a ﬁeld in cosmology where the word ether is being used again. It is unclear, however, whether this æther may be regarded in continuation with previous ethers, or it is an altogether new entity. The main goal of this paper is to understand the nature of this new ether in the context of previous instances of this scientiﬁc object. In order to do so, we shall ﬁrst give a brief historical account of the distinct uses the word had assumed in the late nineteenth and early twentieth centuries, before its demise. Then, we shall describe the major attempts to revive the ether over the last century, focusing on the last endeavor: the Æ-theory. In this article, we do not intend to support or reject this new use of the word, but to stress the complexity of establishing a consistent historical narrative of some scientiﬁc objects like the ether. 1 Introduction In a very recent news article in Nature, the journalist and popularizer of science Davide Castelvecchi called everyone’s attention with his claim that cosmologists might have found hints of “an exotic substance called quintessence”or “ether” that “could be accelerating the Universe’s expansion” [10] . The observations he referred to had just been published in Physical Review Letters by cosmologists Yuto Minami and Eiichiro Komatsu and consisted on a very tiny deviation “in the measurement of the cosmic birefringence angle” that, if ultimately conﬁrmed by other observations and other teams, might give evidence of parity violation and, in turn “would have a profound implication for fundamental physics” [48] . The latter article, soberly descriptive as research papers tend to be, contrasts with Castelvecchi’s use of the words quintessence and ether as a way to trigger curiosity. Indeed, ether (or æther) is one of those words that recurrently resurface in popular science, among science dilettantes and, only at times, in the ranks of professional physicists. For the latter, the ether is mostly regarded as a curiosity of the past with no place in contemporary physics. And rightly so, if by ether we mean the quasimechanical medium that Victorians imagined to account for a number of phenomena in electricity, magnetism, optics and even gravitation. Yet, as a number of historians of science have shown, it is very diﬃcult to attribute a clear, well-deﬁned meaning to a word that has played many roles in the history of science [1, 7 , 53] or [57] . This polysemy is not unique to the ether. Terms consistently used in physics for decades or even centuries such as atom, elementary particle, energy or ﬁeld, only to name a few, have often times been redeﬁned and their meanings transformed while preserving the name. There is no secret about these diverse fates of words. It is simply proof of the contingency in the development of physics throughout its history. Perhaps because the ether was at some undetermined time declared dead [52], every attempt to use the word in professional physics has so far always derailed. In this paper we pay attention to one such bid to resuscitate the word ether in the last decades: the so-called Einstein–Æther theory (Æ-theory) in cosmology. Contrary to similar episodes, where proposals often came from the margins of the discipline, reduced to a few papers in second-rate journals,

FAQs

What problem does the paper address about the new use of “ether” in cosmology?

It examines whether the ether appearing in Einstein–Æther Theory is a continuation of earlier scientific ethers or a completely new entity.

How does the paper approach understanding the nature of Æ-theory’s æther?

It first reviews the historical meanings of the word ether in the late nineteenth and early twentieth centuries, then surveys major attempts to revive ether over the last century, focusing on Æ-theory.

What is the paper’s stance toward using or rejecting the word “ether” in current theories?

It does not aim to support or dismiss the new usage, but instead highlights the complexity of constructing a consistent historical narrative for scientific objects like ether.

Aug 28, 2026

Uploaded by Mason