  The role played by Time in the quantum theory is still mysterious by many
aspects. In particular it is not clear today whether the distribution of decay
times of unstable particles could be described by a Time Operator. As we shall
discuss, different approaches to this problem (one could say interpretations)
can be found in the literature on the subject. As we shall show, it is possible
to conceive crucial experiments aimed at distinguishing the different
approaches, by measuring with accuracy the statistical distribution of decay
times of entangled particles. Such experiments can be realized in principle
with entangled kaon pairs.
