Pierre Curie - Research

Research

Prior to his famous doctoral studies on magnetism, he designed and perfected an extremely sensitive torsion balance for measuring magnetic coefficients. Variations on this equipment were commonly used by future workers in that area. Pierre Curie studied ferromagnetism, paramagnetism, and diamagnetism for his doctoral thesis, and discovered the effect of temperature on paramagnetism which is now known as Curie's law. The material constant in Curie's law is known as the Curie constant. He also discovered that ferromagnetic substances exhibited a critical temperature transition, above which the substances lost their ferromagnetic behavior. This is now known as the Curie point.

Pierre formulated what is now known as the Curie Dissymmetry Principle: a physical effect cannot have a dissymmetry absent from its efficient cause. For example, a random mixture of sand in zero gravity has no dissymmetry (it is isotropic). Introduce a gravitational field, then there is a dissymmetry because of the direction of the field. Then the sand grains can ‘self-sort’ with the density increasing with depth. But this new arrangement, with the directional arrangement of sand grains, actually reflects the dissymmetry of the gravitational field that causes the separation.

Pierre worked with his wife Marie Curie in isolating polonium and radium. They were the first to use the term "radioactivity", and were pioneers in its study. Their work, including Marie's celebrated doctoral work, made use of a sensitive piezoelectric electrometer constructed by Pierre and his brother Jacques.

Pierre and one of his students made the first discovery of nuclear energy, by identifying the continuous emission of heat from radium particles. He 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.

The curie is a unit of radioactivity (3.7 x 1010 decays per second or 37 gigabecquerels) originally named in honor of Curie by the Radiology Congress in 1910, after his death. Subsequently, there has been some controversy over whether the naming was in honor of Pierre, Marie, or both.

In the late years of the nineteenth century, Pierre Curie was investigating the mysteries of ordinary magnetism and simultaneously became aware of the spiritualistic experiments of other European scientists, such as Charles Richet and Camille Flammarion. Pierre Curie initially thought that systematic investigations into the paranormal would help him with some unanswered questions about magnetism (Hurwic 1995, p. 65). He wrote to his fiancée Marie, "I must admit that those spiritual phenomena intensely interest me. I think in them are questions that deal with physics" (Hurwic 1995, p. 66) Pierre Curie's notebooks from this period show he read many books on spiritualism. (Hurwic 1995, p. 68)

About some séances with Eusapia Palladino, Pierre Curie wrote to physicist Georges Gouy in a letter dated 24 July 1905 (Hurwic 1995, p. 248):

"We had at the Psychology Society a few séances with the medium Eusapia Paladino. It was very interesting, and truly those phenomena that we have witnessed seemed to us to not be some magical tricks—a table lifted four feet above the floor, movements of objects, feelings of hands that pinched you or caressed you, apparitions of light. All this in a room arranged by us, with a small number of spectators all well known and without the presence of a possible accomplice. Cheating would only be possible if the medium had extraordinary abilities as a magician. But how to explain the different phenomena when we are holding her hands and legs, and the lighting of the room is sufficient to see everything going on?"

Pierre did not go to séances as a mere spectator, and his goal certainly was not to communicate with some spirits. He saw the séances as scientific experiments, tried to monitor different parameters, took detailed notes of every observation. (Hurwic 1995, p. 247)