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A presentation on Niels Bohr.

Mayumi Watabe

on 21 August 2013

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Transcript of PHYSICS "13

Stage I: Early Years
Before we start, I can hear you asking yourselves,
"Who's Niels Bohr?
Well, Niels Henrik David Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics. Bohr was also a philosopher and a promoter of scientific research.
A Physicist, mentor, friend, husband, and father is born
On October 7 of 1885 in Copenhagen, Denmark, a baby boy was born to Christian Bohr, a professor of physiology at the University of Copenhagen, and Ellen Adler Bohr, who came from a wealthy Danish family, as the second of three. He was named as Niels Henrik David Bohr. Before him was his sister, Jenny. And after him was his brother Harald.
His early interest in Physics was sparked
His father, being a professor in physiology, brought his work home most days. And in those days, Bohr was very interested in what his father did. His father was actually glad at his interest and decided to lecture him on the basics.
First Days of School to Graduation
At the age of seven, Bohr entered the Gammelholm Latin School. In 1903, he enrolled as an undergraduate at the Copenhagen University. And, predictably, he majored in Physics. His professor was Professor Christian Christiansen. Though Niels was older, Harald received his PhD before him for the reason that Niels had a huge thesis to complete and in which his time as a student had to be extended.
Stage II: Life Beyond Physics
What lies behind the workload Bohr was known for?
Her name was Margrethe Nørlund
In Early 1910, Bohr met the charming Margrethe Nørlund, who was the sister of the mathematician Niels Erik Nørlund. Unable to resist being without her, he decided to be wed to her. On August 1st, they were married in a civil ceremony at the town hall in Slagelse.
Honey, I'm pregnant
Years later, the couple soon grew into a big family. They had a total of six children. Unfortunately, two of them died. The oldest, Christian, died in a boating accident in 1934, and the other, Harald, died from childhood meningitis. Just like their father, the rest grew on to lead successful lives. Aage Bohr became a successful physicist and was awarded a Nobel Prize. Hans Henrick, too became a physicist. Erik, a chemical engineer. And Ernest, a lawyer, who also like Harald became an Olympic athlete in field hockey.
Random yet Interesting Facts

During WWII, Bohr offered a place for Jewish Scientists to live and work.
Not only did Bohr make major contributions to theoretical physics, he was also a wonderful administrator.
During the debate about Quantum Theory with Albert Einstein, Einstein said "God does not play dice." Bohr replied by saying "Einstein, stop telling God what to do!"
Stage III: The Bohr Model
The discovery and development of the Bohr Model.
In 1911, Bohr traveled to England to meet different professors from different universities and laboratories to attend lectures. Among them were J.J Thompson, James Jeans, and Joseph Larmor. He did some research on cathode rays but failed to impress Thompson. But he had success with Ernest Rutherford whose Rutherford model of the atom had been challenged by Thompson's plum pudding model. But what really intrigued Bohr was a paper by Charles Galton Darwin on electrons. Thus his research began.
Ha! Beat that, Thompson!
In 1885, Johann Balmer had come up with his Balmer series for describing the visible spectral lines of a hydrogen atoms:

In the first paper of his Trilogy, Bohr was able to derive it from his model:
The Bohr Model
In a Nutshell
Stage IV: Quantum Mechanics
A gathering of the centuries.
And the Nobel Prize goes to...
The Nobel Prize are known as the highest award one can receive in literature, medicine, physics, chemistry, and peace. The Noble Prizes started after Alfred Noble passed away. He left a fund of $9,000,000 to support these prizes and be presented as awards, and the prizes averaged about $ 40,000 each. This was a lot of money when these prizes started. The first Nobel prizes were awarded on the anniversary of Nobel's death which was December 10, 1901.
Here Come The Nazis
The rise of Nazism in Germany prompted many scholars to flee their countries. Most of the refugees were Jewish, but others were opponents of the Nazi regime.
Stage V: The Manhattan Project
With the dominance of Hitler, physicists must come together to create the Atomic Bomb before he does.
Conclusion and Legacy
The mark Bohr left on the world and on the lives of many.
A Physicist, mentor, friend, husband, and father has died
Bohr died of heart failure at his home in Carlsberg on 18 November 1962. He was cremated and his ashes buried in the family plot in the Assistens Cemetery in the Nørrebro section of Copenhagen, along with those of his parents, his brother Harald, and son Christian. Years later, his wife's ashes would also be interred there.
The Legacy
Bohr received numerous honours and accolades. These include having the Bohr model's semicentennial commemorated in Denmark on 21 November 1963 with a postage stamp depicting Bohr, the hydrogen atom and the formula for the difference of any two hydrogen energy levels. An asteroid, 3948 Bohr was also named after him, as was bohrium, the chemical element with atomic number 107.
The Next Generation: Bohr
The last legacy was not a theory nor a revolutionary debate, but a handful of children to carry on the Bohr bloodline. His children grew on to tell the tale of their father, one of the most brilliant minds that have lived on this planet, a man who left his mark to benefit our lives and to expand our views of Physics.
Oh, hey Albert.
In a nutshell, Quantum Mechanics is the study of the behavior of matter and energy at the molecular, atomic, nuclear, and even smaller microscopic levels. In the early 20th century, it was discovered that the laws that govern macroscopic objects do not function the same in such small realms. While at the Seventh Solvay Conference, which was devoted to the atomic nucleus, in Brussels, Bohr and plenty other well-known physicists engaged in different discussions. Among them all, Bohr had the most good-natured arguments with Einstein.
In 1927 in Copenhagen, Bohr developed his uncertainty Bohr embraced the new principle, and in a paper he presented at the Volta Conference at Como in September 1927, he demonstrated that the uncertainty principle could be derived from classical arguments, and without quantum terminology or matrices.
The Nobel Prize in Physics
In 1922, Bohr was awarded the Nobel Award in Physics for his services in the investigation of the structure of atoms and of the radiation emanating from them.
Other Notable Awards
Aside from being awarded the Nobel Prize in Physics, he was awarded many others. Some being the Franklin Medal, which was a solar and engineering award presented by the Franklin Institute, of Philadelphia, PA, USA. The Order of the Elephant, which is the highest order of Denmark. And the Atoms for Peace Award, in which Bohr was the first ever to receive the award.
Quick Thinking
In April 1940, early in the Second World War, Nazi Germany invaded and occupied Denmark. To prevent the Germans from discovering Max von Laue's and James Franck's gold Nobel medals, Bohr had de Hevesy dissolve them in acid. In this form, they were stored on a shelf at the Institute until after the war, when the gold was precipitated and the medals re-struck by the Nobel Foundation. Bohr kept the Institute running, but all the foreign scholars soon departed.
In 1943, fearing arrest, Bohr fled to Sweden, where he persuaded King Gustav V of Sweden to make public Sweden's willingness to provide asylum. In November 1943, he was flown to Britain and joined the Tube Alloys nuclear weapons project, and was part of the British team of physicists who worked on the Manhattan Project. After the war, Bohr called for international cooperation on nuclear energy. He was involved with the establishment of CERN, and became the first chairman of the Nordic Institute for Theoretical Physics in 1957. He was also involved with the founding of the Risø DTU National Laboratory for Sustainable Energy.
Sworn to Secrecy
In 1938 many people feared that Hitler would build an atomic bomb after word spread that German scientist had split the uranium atom (fission). However, one of Hitlers mistakes was his persecution of Jewish scientists. This persecution resulted in numerous scientists seeking asylum in the United States. One such scientist was Albert Einstein. Einstein, abandoning his belief in pacifism, urged then president Franklin Roosevelt to develop an atomic bomb before Hitler did. Eventually Roosevelt agreed and the United States attempt at building the atomic bomb was codenamed The Manhattan Project. By 1945, the project had nearly 40 labratories and factories which employed approximately 200,000 people. Among these employees were some of the greatest scientist that have ever lived. Included in this lot were Albert Einstein, Enrico Fermi, Richard Feynman, J. Robert Openheimer, and Harold Urey (and this is but a hand full of the many).
On August 6, 1945 the American B-29 bomber known as the Enola Gay released the first atomic bomb to be used in warfare. The 9,000 pound bomb nicknamed "Little Boy" detonated in Hiroshima, Japan. "Little Boy's" explosion was catastrophic and resulted in 66 thousand instantanous deaths. Total vaporization from the blast measured one half a mile in diameter. Total destruction ranged one mile in diameter and serious blazes extended as far as three miles in diameter. Realizing what they've done, Einstein and a handful of other scientists involved in this project signed the Russell–Einstein Manifesto which states that no one ever recreate the Atomic Bomb ever.

England, here I come!
Reaction to the Trilogy was mixed. Many older physicists like Thomson and Rayleigh did not like it, although Emil Warburg thought highly of it, but the younger generation, including Ernest Rutherford, Albert Einstein, Max Born and Arnold Sommerfeld saw the Trilogy as a breakthrough.
Bohr said that the electrons in an atom can be found only in certain, discrete energy levels, unless they are absorbing or releasing energy as they move from one allowed state to another. According to the model, when an excited electron returns to a lower allowed state it gives off electromagnetic energy with a wavelength that is equivalent to the difference in energy between the state from which the electron came and the state where it ends up. These various wavelengths of light constitute the spectrum of an element.
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