Einstein’s Ether: Why did Einstein Come Back to the Ether?

Aug 28, 2026

Uploaded by Rhys

The paper analyzes why Einstein returned to an ether concept after initially dispensing with it in the development of special relativity. By tracing links among Poincaré’s pre-1905 efforts, Minkowski’s “absolute world” spacetime framework, and Mach’s ideas about rotational dynamics, the text argues that Einstein’s 1920 reasoning remained close to Poincaré’s earlier approach. The discussion highlights limits of overly simplistic comparisons and frames ether as a medium mediating inertial and gravitational effects.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

Introduction

Background: Ether, Mach, and the emergence of spacetime

Einstein’s 1920 reasoning compared with Poincaré

Einstein returns to a revised ether concept after 1916

Apeiron , Vol. 8, No. 3, July 2001 19 Einstein’s Ether: F. Why did Einstein Come Back to the Ether? Galina Granek Department of Philosophy, Haifa University Mount Carmel, Haifa 31905, Israel (e-mail: [granek@mscc.huji.ac.il](granek@mscc.huji.ac.il)). According to conventional wisdom, Poincaré failed to derive a relativity theory mainly as a result of his stubborn adherence to the ether. In (1905) Einstein constructed a relativity theory that was based on the assertion that the ether was superfluous. In 1908 Minkowski formulated the theory of the “absolute world”. The nineteenth century ether no longer existed. A new kind of ether (space-time) came into being. One could keep on maintaining the ether, and at the same time strip it of the notion of absolute rest. Einstein seemed to agree, and after 1916 he returned to the ether. In 1920 he combined Minkowski’s absolute world concept and Mach’s ideas on rotational movements: in order to cancel action-at-a-distance, the inertial interactions between matter and fixed stars should be mediated by a medium. Einstein called Mach’s medium“Mach’s ether”. In this paper I demonstrate that Einstein’s 1920 reasoning hardly differed from the one Poincaré had presented prior to 1905. Thus, whil Einstein was a hero because he did away with the ether, this situation lasted a few years only. This is not to underestimate the magnitude of © 2001 C. Roy Keys Inc. Apeiron , Vol. 8, No. 3, July 2001 20 Einstein’s achievement, but to emphasize the limits of simplistic comparisons between Einstein and Poincaré . Introduction ach himself had already noticed Minst296a;ntEaneousnglishtactionranslati-aton-)a:-distance the problem regarding (Mach, 1893, pp. 295- Nobody would believe that the chance disturbance—say by an impact—of one body in a system of uninfluenced bodies which are left to themselves and move uniformly ina straight line, where all the bodies combine to fix the system of coordinates, will immediately cause a disturbance of the others as a consequence. And the relative motion (1893, p. 282): “[…] is determined by a medium in which K exists. In such a case we should have to substitute this medium for Newton’s absolute space”. Therefore (Mach, pp. 282-283): We should […] have to picture to ourselves some other medium, filling, say, all space, with respect to the constitution of which and its kinetic relations to the bodies placed in it we have at present no adequate knowledge. In itself such a state of things would not belong to the impossibilities. […] we might still hope to learn more in the future concerning this hypothetical medium; and from the point of view of science it would bein every respect a more valuable acquisition than the forlorn idea of absolute space. Einstein solved Mach’s problem by using Poincaré’s ideas and Minkowski’s ideas (see my three papers “Poincaré’s ether” for © 2001 C. Roy Keys Inc. Apeiron , Vol. 8, No. 3, July 2001 21 Poincaré’s ideas). He corrected Poincaré’s reasoning and he called Mach’s “hypothetical medium” the ether (as Poincaré did), but Einstein’s ether was not at absolute rest. Einstein then identified this new ether with space-time in accordance with Minkowski’s “absolute world” concept: Minkowski formulated the theory of the “absolute world” in his lecture,“Space and Time”(1908, p. 107): the laws of nature are invariant under the Lorentz group. The words “Relativity Postulate”mean the requirement of invariance under the Lorentz group. The postulate means that only the four-dimensional world (i.e., spacetime) in space and time is given by phenomena. Projection in space and in time may still be undertaken with a certain degree of freedom. Therefore, Minkowski called the postulate of relativity,“the postulate of the absolute world”(Postulat der absoluten Welt ). The Lorentzian nineteenth century ether, corresponding to the idea of absolute rest, no longer existed; however a new kind of ether (i.e. the space-time s

FAQs

Why did Einstein initially reject the ether and later return to it?

Einstein first constructed relativity based on the claim that ether was superfluous, but later returned to an ether-like medium aligned with spacetime ideas and the needs of inertial/gravitational interaction.

How does the paper connect Einstein’s 1920 arguments to Poincaré’s earlier work?

The paper demonstrates that Einstein’s 1920 reasoning hardly differed from the one Poincaré had presented before 1905, suggesting continuity rather than a complete reversal.

What role do Minkowski’s “absolute world” and Mach’s medium play in the argument?

Minkowski’s “absolute world” motivates a four-dimensional spacetime ether framework, while Mach’s medium is invoked so rotational effects are mediated by a medium rather than via action at a distance.

Aug 28, 2026

Uploaded by Rhys