On May 12, 1879, William Thomson (later Lord Kelvin), the first British Prime Minister to win a Nobel Prize for physics,Serie A Overview delivered a paper titled "The Motion of a Body in Space" at the São Paulo Conference on Electricity and Magnetism.
In his speech, Thomson described how he had recently discovered that the motion of a body in space could be explained by the principle of relativity, which was later known as the theory of relativity. He also presented evidence that showed that this theory could explain the motion of planets and stars in our solar system.
Thomson's breakthrough at the São Paulo Conference marked a significant advancement in the field of physics and laid the foundation for modern theories of electromagnetism and gravitation. His work has since been recognized as one of the most important contributions to science in the 19th century.