The American Institute of Physics Bulletin of Physics News
Number 775 April 26, 2006 by Phillip F. Schewe, Ben Stein, and
Davide Castelvecchi
                
LOOKING FOR A CRACK IN THE UNIVERSE, in the form of very faint field
pervading the Cosmos, one that exerts a force on electron spin,
would be equivalent to the end of Lorentz invariance. Lorentz
invariance is the proposition that says that the laws of physics are
the same for an observer at rest on the Earth or one who is rotated
through some angle or traveling at a constant speed relative to the
observer at rest. An important ingredient in Einstein's theory of
special relativity, Lorentz invariance has been borne out in
numerous experiments. A new experiment conducted at the University
of Washington has sought such an anomalous field and not found it
even at an energy scale no larger than 10^-21 eV. This is the most
stringent search yet (by a factor of 100) for
Lorentz-invariance-violating effects involving electrons.