The 1919 measurement of the deflection of light

TL;DR

The 1919 eclipse measurement of starlight deflection confirmed Einstein's general relativity, influencing astronomy and cosmology, and laid the foundation for ongoing experimental tests and gravitational lens studies.

Contribution

This paper reviews the historic 1919 measurement, its impact, and discusses modern techniques and applications like radio astronomy and gravitational lensing.

Findings

First verification of general relativity by eclipse measurement

Development of gravitational lensing as an astronomical tool

Modern radio measurements of light deflection and Shapiro delay

Abstract

The measurement of the deflection of starlight during a total solar eclipse on May 29, 1919 was the first verification of general relativity by an external team of scientists, brought Einstein and his theory to the attention of the general public, and left a legacy of experimental testing that continues today. The discovery of gravitational lenses turned Einstein's deflection into an important tool for astronomy and cosmology. This article reviews the history of the 1919 measurement and other eclipse measurements, describes modern measurements of the effect using radio astronomy, and of its cousin, the Shapiro time delay, and discusses gravitational lenses.