Niels Henrik David Bohr

 

Niels Bohr was born on October 7, 1885, in Copenhagen, Denmark. His father was the internationally famous physiologist Professor Christian Bohr who was born in 1855 and was the son of a headmaster, later professor, H.G.C. Bohr and his wife n6e Rimestad. Christian Bohr received a medical degree in 1878, but never practiced as a doctor. Originally Christian wanted to be a zoologist, but Japetus Steenstrup convinced his to become a doctor first. He may have felt that Christian's abilities and interest lay more in the exact than in the purely descriptive scientific disciplines. At the age of 22, Christian Bohr wrote his first scientific work, and three years later, he defended his thesis for the degree of Doctor or Philosophy at the University of Copenhagen.

Niels Bohr's home was one filled with openness and refinement. He lived in the home with his parents and his younger brother, Harald, and his older sister Jenny. Niels' home was not only intellectual, but which was also among the most distinguished in outlook and humanity. Christian and Ellen Bohr were to a rare degree able to give their children an education. This education opened up the children's possibilities for success. As a child Niels was always very interested in working with his hands in practical activities. He showed interest in woodwork, which he later applied to his work with metal. Niels Bohr studied at the University of Copenhagen, starting in 1903. He won a gold metal from the Royal Danish Academy of Sciences for his theoretical analysis of the vibrations of water jets as a way to determine surface tension. He then received his Master's degree from the University of Copenhagen in 1909. He continued his work and received his doctorate in 1911 with his thesis studies on the "election theory of metals."

Bohr then went to England to study with Sir J.J. Thomson at Cambridge. He intended to spend his entire trip working with Thomson but he did not get along with Thomson, so after meeting Ernest Rutherford in Cambridge in December 1911. Bohr then moved to Manchester in 1912. While there he worked with Rutherford's group on the structure of the atom. Bohr always had an ability to see the faults in ideas. He knew that something about Rutherford's theory was incorrect so he set out to discover what was wrong. Using quantum ideas due to Planck and Dinstein, Bohr concluded that an atom could exist only in a discrete set of stable energy states. Bohr used Rutherford's findings that an atom is made up of a positively charged nucleus surrounded by negatively charged electrons and proposed that electrons travel in orbits, with the outer orbits holding more electrons than the inner ones. He found that the outer orbits determine the atom's chemical properties. Atoms were known to emit radiation. Bohr suggested an electron jumping from an outer orbit to an inner one caused this, emitting a light. Later other physicists expanded his theory into quantum mechanics.

Bohr returned to Copenhagen, in 1912 and continued to develop his theory of the atom. He completed his work in 1913. That same year he published three papers of great importance on the theory of the atom that influenced Einstein and other scientists. The first paper was on the hydrogen atom. The next two papers were on the structure of atoms that were heavier than hydrogen. During World War II, the Nazis occupied Denmark. Bohr was of Jewish origins so he escaped with his family by taking a fishing boat to Sweden in 1943. From there he went to England and began working on the nuclear fission bomb. Later he went to the US where he continued to work on it. Niels married Margrethe Norlund in 1912. They had a very happy marriage. They had their first child, Christian, in 1916. In the 1920s they had four more sons, Hans, Erik, Aage, and Ernest. Niels was a great father and a great person.

After being a lecturer in Copenhagen, then in Manchester, Bohr was appointed to chair of theoretical physics at the University of Copenhagen in 1916. The Institute of Theoretical Physics was created for him, and he served as its director until he died in 1962.

Bohr is best known for his investigations of the atomic structure and also for his work on radiation, for which he won the Nobel Prize in 1922. Bohr's view of quantum theory was the theory that was eventually accepted. Other contributions that Bohr made included his theoretical description of the periodic table of elements around in 1920, his theory of the atomic nucleus being a compound structure in 1936, and his ideas of uranium fission in terms of the isotope 235 in 1939. In 1943 he began to work on the project to make a nuclear fission bomb.

Niels Bohr contributed greatly to physics and chemistry, making many things possible by increasing the understanding of atoms. He was an honest man who cared deeply not only for the people close to him, but all of the people of the world. I look up to Niels Bohr not only for his accomplishments in science, but also for being a great humanitarian.

 

Bibliography

 

Blaedel, Niels. Harmony and Unity - Wisconsin: Science Tech Publishers, ©1988.

INTERNET REFERENCE ADDRESS

http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Bohr_Niels.html

 

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