Used with
permission of Maiken Naylor, University at Buffalo, Buffalo, NY, USA,
http://ublib.buffalo.edu/libraries/units/sel/exhibits/stamps
Danish physicist Niels Bohr (1885-1962) won the Nobel prize in physics for his model of the hydrogen atom, in which the electron occupied discrete energy levels, or orbits, around the nucleus, and radiated or absorbed energy only when moving between energy levels, whereas classical theory predicted that an orbiting electron (a moving charge) should radiate energy continuously. This model of circular orbits was able to account for the major series of the hydrogen spectrum, but it was left to Sommerfeld to explain its fine structure by adding elliptic orbits to the model, resulting in the Bohr- Sommerfeld atom. Bohr is commemorated with circular electron orbits on the Swedish stamp but with an elliptic orbit on the Danish stamp, which also indicates the quantized nature of the energy transition between orbits. The stamp showing Bohr and his wife on a garden bench enjoys some minor fame because the bench only has three legs.