PHYSICS: Looking for Lorentz Violations

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Science  02 Feb 2007:
Vol. 315, Issue 5812, pp. 574d-575d
DOI: 10.1126/science.315.5812.574d

Although symmetries underlie deep principles in physics (such as the conservation of momentum), ultraprecise measurements have revealed slight exceptions such as the CP (charge-parity) violation in some radioactive decays. Lorentz symmetry, which dictates that experimental measurements should not depend on whether the apparatus is moving at steady velocity or standing still, is a cornerstone of special relativity. However, some researchers believe that there may be extremely small violations of Lorentz symmetry which, if measured, could provide tests of string theory and quantum gravity.

Experiments are now underway to search for Lorentz violations by trapping antihydrogen atoms. Altschul has calculated the properties of another possible experimental test known as vacuum Embedded Imageerenkov emission. High-energy charged particles passing through matter give off light, such as the eerie blue glow of radioactive waste in a storage pool. If Lorentz symmetry is violated, particles moving through empty space may also emit Embedded Imageerenkov light. Observing such emission would be extremely difficult but could serve as a valuable complement to the antimatter experiments. — DV

Phys. Rev. Lett. 98, 041603 (2007).

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