Niels Bohr was a Danish physicist whose work was instrumental in the understanding the structure of atoms.  Along with Einstein, he is regarded as one of the most influential quantum physicists of the twentieth century, and was also intimately involved in the top secret Manhattan Project.

Born to a well-to-do family in Copenhagen, Bohr's father was a Christian while his mother was Jewish.  As a young man, he was both a capable student as well as a talented athlete.  Although initially interested in pursuing a degree in philosophy, Bohr became interested in the sciences when he won a national science competition during his undergraduate years.  Abandoning philosophy, he dedicated himself entirely to physics and completed a doctorate in 1911.

By 1916, Bohr had accepted a teaching position at University of Copenhagen and continued research into the quantum theory.  In 1922, he was awarded the Nobel Prize in Physics and forged a friendship with Einstein which continued throughout their lives.  For most of the 20s and 30s, Bohr continued teaching at the University and served as the Director of the Institute of Theoretical Physics (which he had founded). 

In October 1943, Bohr fled to Sweden when the Nazi's advanced.  Nearly 8,000 people (approximately 99% of the nation's Jewish population) were rescued in this way, thanks to a collective effort by Danes to evacuate their friends and neighbors to Sweden. 

Fearing that the Germans were developing nuclear weapons, Bohr joined the U.S. Manhattan Project.  Later years, he would describe his involvement as an attempt to prevent the wide-scale development of nuclear weapons.  He was more concerned with establishing an international 'consortium' to regulate such technologies.  Eventually of course, Bohr's vision was realized when years later the International Atomic Energy Association was formed.

Niels Bohr died of heart failure in 1962.  His son Aage Bohr would also go on to win the Nobel Prize for Physics in 1975.