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Einstein’s Gyros

Illy, József (2019) Einstein’s Gyros. Physics in Perspective, 21 (4). pp. 274-295. ISSN 1422-6944.

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Einstein’s life-long effort to develop a theory that unifies gravitation and electromagnetism was not a purely theoretical enterprise. The technical environment of a gyrocompass factory triggered his search for a novel connection between the rotation of an electrically uncharged body and its magnetic field. The dimensional equality of the electric unit charge and the mass of a body multiplied by the square root of the gravitational constant hinted at a nonsensical electric charge, to which he gave the name “ghost charge.” He felt that he found a fundamental unity of gravitating mass and electricity, a hitherto undiscovered law of nature. Two physicists offered to assist him in finding evidence of this peculiar electric charge. Peter Pringsheim performed experiments with deionized gases and Teodor Schlomka made measurements of the earth’s magnetic field from balloons and airplanes; Schlomka also executed a thorough literature search and placed Einstein’s efforts in their historical context.

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Additional Information:© 2019 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. First Online 05 December 2019. I express my sincere thanks to Professor Diana Buchwald, Professor Daniel Kennefick and Professor A. J. Kox for discussion and advises; to my colleague Jennifer James Nollar for acquiring documentary sources about Blackett’s Princeton visit; and to Anne Barrett, Imperial College, London, for information about Blackett’s estate. I gratefully thank co-editors-in-chief Joseph D. Martin and Richard Staley for their comments, suggestions, and language corrections. Special thanks for Dr. Roni Grosz, Dibner Curator of the Einstein Archives, Jerusalem, for permission to quote from Einstein’s unpublished letters.
Errata:The article ‘Einstein’s Gyros’ written by József Illy was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 5 December 2019 with open access. With the author(s)’ decision to step back from Open Choice, the copyright of the article changed on 30 January 2020 to © [Springer Nature Switzerland AG] 2020 and the article is forthwith distributed under the terms of copyright.
Subject Keywords:Einstein; electrogravitational coupling; rotation and magnetism; terrestrial magnetic field
Issue or Number:4
Record Number:CaltechAUTHORS:20191206-090511354
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Official Citation:Illy, J. Phys. Perspect. (2019) 21: 274.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100223
Deposited By: Tony Diaz
Deposited On:06 Dec 2019 18:07
Last Modified:12 Feb 2020 00:15

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