  I critize some of the conclusions in the paper by Danan et al, in particular
their claim that '(S)ome (of the photons) have been inside the nested
interferometer ... but they never entered and never left (it) ...'. A standard
quantum-mechanical analysis also casts doubts on their statement that '(o)nly
the description with forward and backward evolving quantum states provides a
simple and intuitive picture of pre- and postselected quantum particles.'
