From Einstein and Eddington to LIGO: 100 years of gravitational light deflection


On May 29th 1919, during a total solar eclipse, Einstein's theory of general relativity was confirmed to be correct. Stars behind the obscured Sun could be seen on Earth as the light rays they emitted were deflected due to the Sun's spacetime curvature within the value of 1.75 arcseconds predicted by the theory.

The observations were carried out at the Príncipe Island, off the western equatorial coast of Central Africa, and in the city of Sobral, in Brazil. Two expeditions, carefully planned by the Astronomer Royal Frank Dyson, left England in early March 1919 and sailed to Lisbon and then Funchal where they separated. Arthur Eddington, the renowned Cambridge astrophysicist, went off with his team to Príncipe and Andrew Crommelin and Charles Davidson, Greenwich Observatory astronomers, were bound for Sobral.


This is one of the most acclaimed events in the history of science with Einstein being made instantaneously a worlwide figure. Science had demonstrated once again that people from different countries could be united in a common goal. At the time, the First World War had just ended and British and German scientists were eager to close hands looking towards a new future.

Since then, general relativity has passed a large number of other impressive tests, the most recent and notable one being the LIGO first detection of gravitational waves generated by the collision of two 30 solar mass black holes.

This conference will be held from May 26th to May 30th, 2019, precisely one hundred years after the 1919 eclipse, at Resort Bom Bom in Príncipe Island, 2.5 Km away from the site of Eddington's observations, which took place at Roça Sundy.

The main aim of the conference is to celebrate such an important date with a gathering of worldwide experts to reflect on the legacy left by Einstein and Eddington from the event itself and to discuss the subsequent startling developments in the fields of astrophysics and gravitation, namely, black holes, gravitational waves, and cosmology.

The conference also aims at drawing the attention of the local population towards the historical importance of the 1919 observations and science in general and is included as the scientific component of the Eddington@Sundy project.

Participation: Participation and presentation are by invitation only. The number of participants is limited in accordance with the capacity of the resort Bom Bom.

Scientific and Organizing Committee: José Sande Lemos, Vítor Cardoso, and Carlos Herdeiro.

Secretariat: Dulce Conceição ( and Rita Teixeira (


System network manager: Sérgio Almeida


Sponsors: CENTRA - Center for Astrophysics and Gravitation, IST, FCT (UID/FIS/0009972013 & UID/FIS/0009972019), Eddington at Sundy, Resort Bom Bom, HBD.


Credits for the text: José Sande Lemos, Vítor Cardoso, and Carlos Herdeiro.