Arthur Eddington: Discoveries & Contributions

Instructor: Michael Blosser

Michael has a Masters in Physics and a Masters in International Development. He has over 5 years of teaching experience, teaching Physics, Math, and English classes.

This lesson will introduce you to the physicist Arthur Eddington, exploring his discoveries in the field of astrophysics and his work on general relativity as well as other scientific contributions to the field of physics.

Arthur Eddington

Arthur Eddington
Arthur Eddington

Arthur Eddington is a famous astronomer, physicist, and mathematician who made numerous contributions to the field of astrophysics and was a leading scholar on Albert Einstein's theory of general relativity. Eddington also spent most of his later life and career searching for a unified or fundamental theory of physics.

This lesson will introduce you to Eddington's numerous discoveries and scientific contributions and explain why they are so important to the scientific and physics community today.


Although Arthur Eddington dabbled in numerous areas of physics and was a mathematician as well, some of his most important contributions were in the field of astrophysics, or the physics of the stars and other celestial bodies. In 1906, Eddington became a chief assistant at the Royal Observatory in Greenwich, England. During his time there (1906-1913), Eddington led astronomical expeditions to Malta and Brazil, researched the motions of the stars, and published a significant paper about the movements of a globular stellar system.

Eddington took a position as director of the prestigious observatory at Cambridge University in 1914. That same year he published a revolutionary book about the Milky Way Galaxy called Stellar Movements and the Structure of the Universe. In 1916, during Eddington's research on stars, he determined that it is a star's thermal pressure and radiation pressure that counter its gravitational force and prevent it from collapsing.

Additionally, one of Eddington's main contributions to the field of astrophysics is his discovery of the connection between a star's mass and its luminosity. Luminosity is how bright a star is and is dependent on the energy emitted by the star. Although Eddington's discoveries and theories concerning stars were generally disregarded at that time, they were eventually seen as revolutionary, and his 1926 book, The Internal Constitution of the Stars, is now seen as a standard astrophysics text.

General Relativity

In his time, Arthur Eddington was seen as one of the leading scholars of Albert Einstein's theory of general relativity. Albert Einstein's theory of general relativity is one of the fundamental theories in physics that concerns gravity, space, time, and mass; how they interact with each other; and how the laws of physics change at speeds near the speed of light or in the presence of a massive source of gravity.

During Eddington's time, Einstein's theory of general relativity was respected but rarely understood by the majority of the scientific community. Eddington helped expand the understanding of this theory by writing the first explanation of it in the English language in 1918 called Report on the Relativity Theory of Gravitation. Eddington also led an astronomical expedition to West Africa in 1919 to observe an eclipse in the attempt to experimentally prove Einstein's theory. Eddington and his team observed that the solar eclipse had displaced the position of the stars beyond its center, a phenomenon that the theory of general relativity predicted.

Eddington's mission confirmed Einstein's fundamental and revolutionary theory only a few years after Einstein proposed it. Einstein, already relatively known at that time, became one of the few scientists to have their theories confirmed experimentally in their lifetime, instantly making him an international sensation. Moreover, Einstein himself considered Eddington's publication, The Mathematical Theory of Relativity, published in 1923, as one of the best explanations and presentations of the theory of relativity in any language.

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