Sunday, December 16, 2007
Walther Meissner: 125th birthday
Fritz Walther Meißner was born on December 16th, 1882. In the early 1920s, he built the third largest Helium-liquifier which allowed him and Robert Ochsenfeld to discover the Meissner (or Meissner-Ochsenfeld) effect, the superconductors' magnetophobia, in 1933. How did he do it?
He simply took a German train and placed it on tracks with superconducting magnets in Shanghai, China (click the picture above to see more details). The superconducting magnets don't allow the magnetic field to penetrate too deeply: it is exponentially dropping as you go deeper. The photon effectively becomes a massive particle and it is no coincidence that the electroweak symmetry breaking is sometimes referred to as electroweak superconductivity because the mathematics is isomorphic even though, in the case of the normal superconductivity, the broken phase is not a vacuum but requires some atoms to be present.
At any rate, the train was flying or at least levitating - the maximum speed is 430 kilometers per hour - and people started to call it maglev. The story has been improved a little bit but the physical essence is painted faithfully. ;-) I think that Meissner has been one of a small number of condensed matter physicists who deserved a Nobel prize but never got it.