His theories combined classical and quantum physics to make a new model of the atom.
This model solved the mystery of the emission spectrum of different chemical elements. It is still the basis for many modern theories.
Niels Bohr's discoveries were so groundbreaking that he was awarded the Nobel Prize in Physics in 1922.
He continued to work on revolutionary theories and eventually teamed up with Werner Heisenberg to develop the principle of quantum mechanics.
He even went on to apply the concept to philosophical reasoning, believing that the evolving concepts of physics had profound implications on human perspectives.
After the World War II, Niels Bohr returned to Copenhagen where he received the Order of the Elephant, Denmark's highest award.
He also served in a number of public roles, including president of the Royal Danish Academy from 1939 until 1962.
His youngest son, Aage Niels Bohr, later became a famous physicist and won the Nobel Prize for Physics in 1975.