P-Violation Manifested at the Molecular Level - A Simple Means for an   Absolute Definition of "Left" vs. "Right"
  P-violation of the nuclear weak force was hitherto believed to manifest itself only in asymmetric $\beta$-emission due to neutron decay. Molecules with space asymmetry (like L and D amino acids) are affected by this parity violation, yielding a parity violation energy difference (PVED) between chiral isomers in the order of $10^{-16}$ ev. In specific cases, where an autocatalytic process is combined with interaction with a selective spin isomer of H$_2$O, this tiny PVED can be amplified to a macroscopic detectable level. We describe such a system through which one can transmit a universal definition of "left" and "right." The procedure is straightforward, yielding an absolute rather than a statistical definition. The argument is illustrated by paraphrasing Feynman's celebrated thought-experiment of communicating spatial directions to an alien. 
Avshalom C. Elizur and Meir Shinitzky