  When a quantum object -- a particle as we call it in a non-rigorous way -- is
described by a multi-branched wave- function, with the corresponding
wave-packets occupying separated regions of the time-space, a frequently asked
question is whether the quantum object is actually contained in only one of
these wave-packets. If the answer is positive, then the other wave-packets are
called in literature empty waves. The wave-packet containing the object is
called a full wave, and is the only one that would produce a recording in a
detector. A question immediately arising is whether the empty waves may also
have an observable effect. Different works were dedicated to the elucidation of
this question. None of them proved that the hypothesis of full/empty waves is
correct - it may be that the Nature is indeed non-deterministic and the quantum
object is not confined to one region of the space-time. All the works that
proved that the empty waves have an effect, in fact, proved that if there exist
full and empty waves, then the latter may have an observable effect. This is
also the purpose and the limitation of the present work. What is shown here is
that if the hypothesis is true, the empty waves have an influence. An
experiment is indicated which reveals this influence. The analysis of the
experiment is according to the quantum formalism. This experiment has the
advantage of being more intuitive and practically more feasible than a previous
proposal also in agreement with the quantum formalism. However, the presently
proposed experiment also shows that the quantum theory is not in favor of the
above hypothesis.

Quantum Physics