The arrow of time in quantum mechanics and in nonlinear optics
  The direct and indirect experimental proofs of a strong time invariance violation in optics are discussed. Time noninvariance for present day becomes the only real physical base for explanation the origin of the most phenomena in nonlinear optics. This is a good cause to introduce the time asymmetry into the dynamical equations of the basic laws of physics. 
Vladimir A. Kuz'menko