Hantarō Nagaoka
Hantarō Nagaoka (長岡半太郎, Hantarō Nagaoka? August 15, 1865 - December 11, 1950) was a physicist Japanese.
He studied in Germany and Austria between 1893 and 1896. In 1904 he developed a planetary model of the atom (Saturnian theory) that proposed a large sphere in the center of which there is a positive charge surrounded by the electrons that orbit it. However, the name of his theory (Saturnian theory) generated great controversy since it was believed that what Nagaoka actually proposed was an atom with a gigantic nucleus compared to its atoms, when in reality what Nagaoka raises with the sphere is the great distance between the nucleus and the electrons.
Later, he did research in the field of spectroscopy. He presided over Osaka University from 1931 to 1934.
Life
Nagaoka was born in Ōmura, Nagasaki, Japan and educated at the University of Tokyo. After graduating in 1887, he worked with the British visiting physicist Cargill Gilston Knott in the field of magnetism. In 1893 he traveled to Europe, where he continued his education at the universities of Berlin, Munich, and Vienna. He also attended, in 1900, the First International Congress of Physicists in Paris, where he heard Marie Curie's lecture on radioactivity, an event that sparked Nagaoka's interest in atomic physics. Nagaoka returned to Japan in 1901 and served as a professor of physics at the University of Tokyo until 1925. After his retirement, he was appointed chief scientist of RIKEN, and also served as the first president of Osaka University. (1931-1934).
Saturnian model of the atom
Physicists around the first decade of the twentieth century had just begun to peek into the structure of the atom. J. J. Thomson's recent discovery of negatively charged electrons (1897) implied that a neutral atom must also contain a positively charged part. In 1903 Thomson suggested that the atom was a sphere of uniformly positive electric charge, with electrons spread out within it like plums would be in a plum pudding, one of the colloquial names given to Thomson's model of the atom.
Nagaoka rejected Thomson's model, because opposite charges are impenetrable by opposite charge. Due to his non-conformity, he proposed an alternative model in which a center of positive charge was surrounded by a number of rotating electrons, similar to Saturn and its rings.
In 1904, Nagaoka developed one of the first planetary models of the atom, such as the Rutherford Atomic Model. The Nagaoka Model was based around the analogy with Saturn (planet) and with theories that explained the stability and gravitational relationships between it and its rings. The point was this: the rings are very stable because the planet they orbit is very massive. This model offered two predictions:
- A very massive core (in analogy to a very massive planet).
- Electrons rotating around the atomic nucleus, tied to that orbit by the electrostatic forces (in analogy to the rings rotating around Saturn, tied to it by its gravitational force).
Both predictions were successfully confirmed by Ernest Rutherford (who mentions Nagaoka's invaluable contribution in his 1911 text in which the atomic nucleus is proposed). However, other details of the model were incorrect. In particular, if the electrons were electrically charged rings of matter, this would cause them to be unstable due to repulsive disruption, which is not the case with Saturn's rings since they are not charged. Nagaoka himself gave up belief in the Saturnian model of the atom in 1908.
Subsequently, Ernest Rutherford and Niels Bohr presented a much more viable model, the Bohr model of the atom, in 1913.
Other jobs
Following his contribution to atomic models, Nagaoka did research in spectroscopy and other fields. In 1909, he published a text dealing with the inductance of solenoids. In March 1924, he described studies in which he succeeded in forming one milligram of gold and some platinum from mercury.
Awards and recognitions
- For a life dedicated to the scientific study, Nagaoka was awarded the Order of Culture by the Japanese government in 1937.
- The lunar crater Nagaoka bears this name in his memory.