Violation of parity and time -

Symmetries of the Universe have always provided theoreticians with a powerful tool in their efforts to understand and unify physics laws. Three of them have shaped physics over the last 50 years: parity (P ), charge conjugation (C), and time-reversal (T ). Today, T -violation remains the most mysterious symmetry violation as it is not understood properly and as much stronger T -violating mechanisms are required to explain the matter-antimatter in the Universe. T -violation could be potentially observed in some recently proposed and on-going experiments with atoms and molecules. In particular, T-violation could manifest itself in electric dipole moment (EDM) elemetary particles and atoms. Here I present results of three calculations in support of emerging searches for T violation: 1) A recently proposed experiment with liquid Xe at Princeton may significantly improve present limits on atomic EDM. We find that the liquid phase reduces the T -violating signal by only 40% still offering an improvement of several orders of magnitude to present limits for several sources of T -violation. 2) To guide emerging searches for electron EDMs with molecular ions, we estimate the EDM-induced energy corrections for hydrogen halide ions HBr and HI. We find that the EDM-signal for the two ions differ by an unexpectedly large factor of fifteen due to a dissimilarity in the nature of the chemical bond. We conclude HI ion may be a potentially competitive candidate for the EDM search. These observations provide guidelines for finding a even better molecular ion candidate. 3) T -violation in an atom leads to the T -odd polarizability β: a magnetic moment μ is induced by an electric field E0 applied to an atom, μ = βE0. We estimate the T violating polarizability for rare-gas atoms He through Rn. Finally, we evaluate a feasibility of setting a limit on electron EDM by measuring μ of liquid Xe. We find that such an