  The claims that the GSI time anomaly is due to the mixing of neutrinos in the
final state of the observed electron-capture processes are refuted. With the
help of an analogy with a double-slit experiment, it is shown that the standard
method of calculation of the rate of an interaction process by adding the rates
of production of all the allowed final states, regardless of a possible
coherence among them, is correct. It is a consequence of causality. It is shown
that the GSI time anomaly may be caused by quantum beats due to the existence
of two coherent energy levels of the decaying ion with an extremely small
energy splitting (about $6\times10^{-16} \text{eV}$) and relative probabilities
having a ratio of about 1/99.
