  It is shown that the hydrodynamic interpretation of a charged quantum
particle leads to a different theoretical prediction for low energy
bremsstrahlung than does quantum electrodynamics (QED). In the calculations,
the electromagnetic fields are treated classically in the hydrodynamic case,
but are quantized in QED. Calculations show the hydrodynamic model to have a
different and more sensitive dependence on the size and shape of the radiating
particle's wave packet then does QED. In particular it is shown that
bremsstrahlung is sometimes greatly reduced when the force acting on the
particle is localized to a volume small compared to the particle's wave packet.
QED exhibits no such reduction. Therefore it is possible to test this effect
experimentally.
  An experiment is proposed. It involves an electron microscope with a Wien
filter for producing monochromatic beam electrons and an accurate energy
measurement of the particle after passing through a local force field.
