What is light? What is ether? - An overview of Einstein’s problem on the abolition of ether and on its inheliminable presence in General Relativity

Aug 28, 2026

A study of the history of theories and experiments on light focuses on the innovative views that emerged from Faraday’s and Maxwell’s field theory of electricity and magnetism. Light is treated as an electromagnetic phenomenon whose waves propagate in ether at the speed of light. Hertz’s experiments are positioned as a key precedent to Einstein’s relativity, clarifying how ether is abolished in special relativity yet reintroduced as a necessary background in general relativity and unified field theories.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages7

Reading Time18 min

AccessFree to download

Introduction

Maxwell’s theory of light: a structural similarity between electromagnetic waves and the waves of light

Heinrich Hertz: ether polarization confirms Faraday’s view of independent existence of forces in space

What is light? What is ether? An overwiew ofEinstein’s problem on the abolition of ether and on its inheliminable presence in General Relativity Salvo D’Agostino-Sapienza Università [di Roma-saldagostino21@gmail.com](di Roma-saldagostino21@gmail.com) Abstract: A study of the history of theories and experiments on Light is very extended, and covers many different aspects. I limit therefore my communication to the innovative views that ensued from Faraday’s and Maxwell’s field theory of Electricity and Magnetism. They discovered that light is an electromagnetic phenomenon, and that electromagnetic waves are propagated in ether with the velocity of light. Hertz’s great experiment was a relevant precedent to Albert Einstein’s revolutionary Relativity. I underline the problem of the abolition of ether in Einstein’s Special Relativity, and ofits introduction in General Relativity. Keywords: Maxwell, Hertz, Helmholtz, Einstein 1. Introduction What is light? What is ether? Answers to these questions divided scientists and philosophers since an innumerable time. In analogy with a vibrating string as the causal source of music and sounds, Kepler, Huygens, and Newton argued that light was the invisible cause of our vision. Newton maintained that the spectral colors are Light’s fundamental components, and that Light is composed of particles. Fresnel made an experiment to convince his hard minded Laplace compatriot of the wavelike nature of light. Maxwell’s field theory, and his electromagnetic theory of Light, fundamentally modified the scientists interests. Faraday’s view of independent existence of magnetic waves as free forces in space, differed from Maxwell’s conviction that ether had a role in his electromagnetic waves propagation. When Hertz in 1889 produced artificial electromagnetic waves, he was more favorable to Faraday’s view than to Maxwell’s conviction, and the transmission of forces through waves propagation represented for him the highest philosophical achievement in science. Maxwell’s theory was for him represented by Maxwell’s equation, a view on the nature of physics theories that had its relevance on Einstein’s revolutionary Relativity. As is known, Einstein thought that the abolition of ether was favorable to the success of his Special Relativity. Further on, however, he found that ether was a necessary background for General Relativity, and Unified Field Theories. 2. Maxwell’s theory of light: a structural similarity betweem Maxwell’s electromagnetic waves and the waves of light James Clerk Maxwell brought into his Electromagnetic theory of light concepts and experimental data obtained from radically different atomistic and field theories. Theories of Mechanics and Electrostatic Potentials, and Wilhelm Weber’s outstanding contributions to Electrodynamics were largely utilized. Green’s and Stokes’s elastic and hydrodynamic theories were also the underlying mathematics of Maxwell’s equations. The identification of the velocity of electric and magnetic waves with the then known value for the velocity of light, a transition from a static to a dynamic field theory, represented an exclusive merit of the Scottish scientist. Maxwell’s contributions to Electromagnetism and Field Theory have been frequently discussed in the history of science literature, with special attention to the discovery of his celebrated equations. However, the connection in Maxwell’s research between Weber’s velocity and velocity of his electromagnetic waves, has not been sufficiently analyzed, to my present knowledge, although this is one of the characteristic feature of Maxwell’s approach to his theory of light (D’Agostino 1996) . The quasi equality between Weber’s velocity of motion of electric masses and Maxwell’s velocity of electromagnetic waves has been misinterpreted as a logical consequence of premises that were foreign to Maxwell. Maxwell infact duly underlined Weber’s systematic definition of absolute units for electric and ma

FAQs

How does the document define light in relation to ether?

It presents light as an electromagnetic phenomenon where electromagnetic waves propagate in ether at the velocity of light.

What role do Maxwell, Faraday, and Hertz play in the ether discussion?

Faraday and Hertz are used to motivate independent forces in space, while Maxwell’s field theory links light to electromagnetic waves. Hertz’s artificial electromagnetic waves serve as a precedent to Einstein’s relativity.

Why is ether abolished in Einstein’s special relativity but introduced in general relativity?

The document emphasizes that Einstein’s special relativity favors the abolition of ether, but later Einstein finds ether necessary as a background for general relativity and unified field theories.

Aug 28, 2026

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