  Practically measurable quantities resulting from quantum field theory are not
described by hermitian operators, contradicting one of the cornerstone axioms
of orthodox quantum theory. This could be a sign that some of the axioms of
orthodox quantum theory should be reformulated. A non-orthodox reformulation of
quantum theory based on integral curves of particle currents is advocated and
possible measurable manifestations are discussed. The consistency with particle
creation and destruction requires particles to be extended objects, which can
be viewed as a new derivation of string theory. Within this reformulation, an
indirect low-energy test of string theory is also possible.
