Swedish Science First Day Cover. These stamps are celebrating 5 of the scientists whose research led to a much greater understanding of the structure of the atom, specifically, the configuration of the electrons in the atom. Each of these: Bohr, Dirac, de Broglie, Heisenberg and Schroedinger received a Nobel Prize for their research. Neils Bohr initially told us that the electron energy levels are quantized and though he said that electrons are found in Solar System style orbits (which was later shown to be incorrect), he still gave us the understanding of how light is absorbed or emitted by an atom. He said that it was due to the electrons moving between energy levels in the atom (think colors in fireworks). Paul Dirac integrated Special Relativity (Einstein) into Quantum Mechanics. Louis de Broglie showed that the electron, which is a particle, did in fact, act as a wave. He successfully diffracted electrons. Heisenberg predicted that one could never precisely determine both the momentum (think velocity) of the electron and it's location. There would always be an uncertainty between the two. Amazingly, he established a mathematical expression for this. Finally Erwin Schroedinger, brought it all together by treating the electron as a standing wave rather than a flying particle. The Schroedinger equation (H*PSI = E*PSI) fundamentally changed theoretical chemistry (ok, and Physics) by defining each electron as a wave function. Schroedinger later predicted the presence of genetic material in living systems. Both James Watson and Francis Crick acknowledge that Schroedinger's writing (What is Life?) inspired them in their search for DNA. There is a pamphlet inside that describes each scientist. Everything is in Swedish. This is the most amazing expression of science in Stamps that I have ever seen.

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