Niels Bohr celebrated with Google doodle

Head to the Google homepage today and you'll see the usual logo altered with some head-scratching physics symbols. That's because today is the 127th birthday of Niels Bohr, Danish physicist and Nobel Prize winner.

Born (Bohrn?) on 7 October 1885, Bohr had science in his blood. His father Christian was a professor of physiology at the University of Copenhagen, and the man who named the phenomenon known as Bohr shift or Bohr effect. This is a macrobiological phenomenon relating to the relationship between blood pH, blood Co2 concentration, and haemoglobin proteins releasing oxygen. (To be honest, it's all a bit complex for a Sunday morning.)

Aged 18, Niels Bohr started studying philosophy and mathematics, receiving his doctorate in 1911. In 1912 he joined the Victoria University of Manchester, and became part of the group of eminent scientists who studied the structure of the atom.

Bohr published his model of atomic structure in 1913, in which he introduced the theory of electrons travelling in orbit around the atom's nucleus, sort of like satellites. He posited that the chemical properties of each element were largely down to the number of electrons it had in orbit.

He also came up with the idea that an electron could drop from a higher energy orbit to a lower, and while doing so would emit a photon of discrete energy. This became the basis of quantum theory, so Bohr's influence can't be overstated.

His work led to him being awarded the Nobel Prize for physics in 1922. He was honoured for services in the investigation of the structure of atoms, and of the radiation emanating from them.

Michale Frayn's 1998 play Copenhagen centred on what might have happened in a 1941 meeting between Bohr and fellow physicist Werner Heisenberg. The two are said to have held differing views concerning the use of nuclear weapons in the second world war.

Bohr died in Copenhagen in 1962 of heart failure.