However, with the discoveries of parity and CP violation in nuetral kaon decay (weak interaction), it became a question as whether time may not be invariant for other processes. T non-Invariance has been observed only in the weak decay of neutral kaons.

The generalized formula for neutron beta decay is:

The D term is a triple product of the neutron spin, electron and antineutrino momentum. This is a T odd, P even term, thus resulting in a possible T non-Invariance effect if it is non-trivial. Else, if this term is zero, then neutron beta decay is T-Invariant.

Other techniques have been investigated to determine the value of the D term. One such technique is to mease whether or not the nuetron contains an Electric Dipole Moment (EDM). If the neutron had a permanent EDM, then upon different polarizations, the value of D would have different signs. Thus, by applying various magnetic pulses, this EDM would exhibit a precession and thus creating a measureable field of its own.