Category: Physics

(This article was adapted from the book What is Radioactivity? The Basics)

It would be difficult–perhaps impossible–to write about the development of atomic science without mentioning the contributions of Niels Bohr and Lise Meitner.

While Ernest Rutherford is credited with describing the nucleus of an atom, it’s Bohr who gave him the clue as to how electrons are arranged on the outer shell of the atom.

Niels Bohr collaborated with many of the most important physicists of the 20th century. In the picture above, he is shown with Albert Einstein. Not only did the work of both men contribute to the development of the atomic bomb, but both were refugees from Nazi ideology. In fact, if it hadn’t been for the Nazis in Germany and Hitler’s genocidal policies, these two scientists probably never would have added their voices to the chorus that urged the bomb be built.

Bohr was born in Denmark. When Germany invaded Denmark, Bohr fled to Sweden and, when Sweden became unsafe he fled with his family to England.  In the race to unlock the power of the atom, Niels Bohr played a critical role, but he was only one of several people who were responsible for understanding how nuclear fission worked. Energy derived from nuclear fission–splitting the atom–powered the atomic bomb.

It was a colleague of Bohr’s, Otto Frisch, who came up with the term ‘nuclear fission’.  Before 1938, the two words ‘nuclear’ and ‘fission’ had never been put together.

Frisch worked in Bohr’s Copenhagen laboratory.  His aunt, Lise Meitner, was  a remarkable physicist who, before 1938, was working with German scientists. These physicists and chemists were trying to split the atom and unlock the enormous energy contained within.  However, Meitner was forced to flee from Germany in ’38.  It was then that she met up with her nephew, Otto, in Stockholm and told him about the work her German colleagues were doing.

Frisch was excited. He and his aunt discussed the issues that prevented the Germans from making progress.  Together, Frisch and Meitner came up with a solution. They discovered a way to unleash the power of the atom.

Frisch contacted Bohr, who was in the US at the time.  Bohr told American scientists about the German efforts to make a bomb and about the progress Frisch and Meitner had made toward splitting the atom.  This information was the final push that led to the American and British determination to build a bomb. The feeling was,  if Germany was so close to owning the weapon, the world was in danger.  The scientists, and the governments who hired them, believed the US and Britain needed to get the bomb before Germany did.

Ironically, Germany never did make an atomic bomb, despite the progress Meitner had witnessed when she worked there. Germany’s failure, many believe, was the result of Nazi ideology.  All the Jewish scientists, including Meitner, Einstein and Frisch, had to leave the country. And, many excellent scientists who might have helped to build the bomb were ordered instead to join the military.  This ‘brain drain’ likely resulted in the failure of Germany’s nuclear program.

Once the US and British governments made the commitment to build a bomb most of the brightest nuclear scientists aided in the effort.  One who did not, who refused to build such a weapon, was Lise Meitner.  As a matter of fact, to the end of her life she expressed regret for the contribution she made to physics which enabled the bomb to be built.