de Paris) in 2015. In 1903, to honor the Curies' work, the Royal Society of London invited Pierre to present their research. Marie Curie was not permitted to give the lecture so Lord Kelvin sat beside her while Pierre spoke on their research. After this, Lord Kelvin held a luncheon for Pierre. While in London, Pierre and Marie were awarded the Davy Medal of the Royal Society of London. In the same year, Pierre and Marie Curie, as well as Henri Becquerel, were awarded a Nobel Prize in physics for their research of radioactivity. Curie and one of his students, Albert Laborde, made the first discovery of nuclear energy, by identifying the continuous emission of heat from radium particles. Curie also investigated the radiation emissions of radioactive substances, and through the use of magnetic fields was able to show that some of the emissions were positively charged, some were negative and some were neutral. These correspond to alpha, beta and gamma radiation. Spiritualism In the late nineteenth century, Pierre Curie was investigating the mysteries of ordinary magnetism when he became aware of the spiritualist experiments of other European scientists, such as Charles Richet and Camille Flammarion. Pierre Curie initially thought the systematic investigation into the paranormal could help with some unanswered questions about magnetism. He wrote to Marie, then his fiancée: "I must admit that those spiritual phenomena intensely interest me. I think they are questions that deal with physics." Pierre Curie's notebooks from this period show he read many books on spiritualism. He did not attend séances such as those of Eusapia Palladino in Paris in June 1905 as a mere spectator, and his goal certainly was not to communicate with spirits. He saw the séances as scientific experiments, tried to monitor different parameters, and took detailed notes of every observation. Despite studying spiritualism, Curie was an atheist. Family Pierre Curie's grandfather, Paul Curie (1799–1853), a doctor of medicine, was a committed Malthusian humanist and married Augustine Hofer, daughter of Jean Hofer and great-granddaughter of Jean-Henri Dollfus, great industrialists from Mulhouse in the second half of the 18th century and the first part of the 19th century. Through this paternal grandmother, Pierre Curie is also a direct descendant of the Basel scientist and mathematician Jean Bernoulli (1667–1748), as is Pierre-Gilles de Gennes, winner of the 1991 Nobel Prize in Physics. Pierre and Marie Curie's daughter, Irène, and their son-in-law,