Number 159 (Story #1), January 6, 1994 by Phillip F. Schewe and Ben Stein|
NEW LAMB SHIFT MEASUREMENTS DISAGREE WITH QED , the theory of quantum electrodynamics. Ironically, QED was devised in the 1950s to explain the Lamb shift (named after Willis Lamb), the slight shift in the energy of an electron bound to a nucleus due to energy fluctuations in the vacuum, which can create electron-positron pairs or virtual photons seemingly out of nothing. Researchers at the Max Planck Institut for Quantum Optics in Garching, Germany have determined experimentally that the Lamb effect should cause the energy of an electron in the lowest energy state, the 1S state, to be shifted upward by 8172.86 Mhz for the hydrogen atom and 8184.00 MHz in the deuterium atom, values which disagree with QED's predictions of 8173.12 MHz for hydrogen and 8184.13 MHz for deuterium. In what they have called "the most stringent test of QED for a bound atom to date," the researchers employed the latest advances in laser and optical spectroscopy to make the measurements of the 1S Lamb shift, which can be measured to greater precision than the 2S and 2P Lamb shifts traditionally studied. However, the researchers do not particularly suspect that any "new physics" is at work here; they believe that a new, unpublished theoretical calculation taking into account previously ignored effects in QED should bring the results into agreement with theory. (M. Weitz et al., Physical Review Letters, 17 January 1994; contact Martin Weitz at Stanford University, 415-723-4666).