And because electrons so readily interact with photons as well, small amounts of laboratory-made orthopositronium might transform into its looking glass counterpart, mirror orthopositronium. By the same token, the mirror form would sometimes convert into the ordinary version. In 1990, researchers at the University of Michigan in Ann Arbor measured the lifetime of orthopositronium and found that it was slightly shorter than predicted by theory. In the May 14 Physics Letters B , Foot and Sergei N. Gninenko of CERN, a particle- physics laboratory in Geneva, suggest that mirror orthopositronium could explain the discrepancy. If orthopositronium decays while in its mirror form, it would go undetected, and that could account for the shorter lifetime measurements.
Extraordinary claims require extraordinary proof.
Previous experiments weren't sensitive enough to confirm or refute the mirror-matter explanation, Foot and Gninenko say. He and his colleagues would confine orthopositronium to a sensitive heat-measuring device, called a calorimeter. The device would be under a strict vacuum to isolate its contents from collisions with other matter, which could confound the findings. But that energy simply wouldn't be there if the orthopositronium had oscillated into its undetectable mirror form. The missing energy would amount to about 1 million electron volts, which is twice the rest mass of an electron, and would be a telltale signature of the mirror universe, Gninenko asserts.