The origins of length contraction: I. The FitzGerald-Lorentz deformation hypothesis

TL;DR

This paper clarifies the historical origins of length contraction, showing that Lorentz and FitzGerald did not initially propose strict contraction but considered various deformation effects in explaining the Michelson-Morley null result.

Contribution

It provides a detailed historical analysis demonstrating that the original hypotheses did not rely solely on strict length contraction, challenging common textbook narratives.

Findings

Lorentz considered multiple deformation effects in 1895.

Strict length contraction was not originally invoked to explain Michelson-Morley.

The Michelson-Morley experiment's analysis reveals issues with standard interpretations.

Abstract

One of the widespread confusions concerning the history of the 1887 Michelson-Morley experiment has to do with the initial explanation of this celebrated null result due independently to FitzGerald and Lorentz. In neither case was a strict, longitudinal length contraction hypothesis invoked, as is commonly supposed. Lorentz postulated, particularly in 1895, any one of a certain family of possible deformation effects for rigid bodies in motion, including purely transverse alteration, and expansion as well as contraction; FitzGerald may well have had the same family in mind. A careful analysis of the Michelson-Morley experiment (which reveals a number of serious inadequacies in many text-book treatments) indeed shows that strict contraction is not required.