A hydrogen atom is exposed to Lyman-alpha raditaion thereby exciting hte electron from the n=1 to hte n=2 level.
Now let the excited atom enter an opaque cavity which blocks out the Lyman-alpha radiation.
The electron will decay from n=2 to n=1 with the emission of Lyman-alpha radiation. Clearly we can capture this radiation so it is no longer available to re-energize the electron on exit.
Upon leaving the opaque cavity the electron will again be excited from n=1 to n=2 by the ambient Lyman-alpha radiation
The processes that occur on entry and exit of the opaque cavity by the electron are clearly independent. We are sucking energy out of hte Lyman-alpha radiation field (which of course we are providing).
Zero-Point Energy Absorption and Emission
A hydrogen atom is exposed to zero-point radiation which is everywhere and according to the Puthoff model is what maintains the ground state; i.e. it is "excited" into the lowest Bohr-orbit.
Now let the atom enter a Casimir cavity in which the zero-point radiation responsible for maintaining the ground state is suppressed.
The electron will "decay" to a sub-Bohr orbit thus emitting energy in some fashion. We proposed to capture this energy.
Upon leaving the Casimir cavity the electron will again be excited back up to the ground state.
The processes that occur on entry and exzit of the Casimiar cavity by the electron are clearly independent. We are sucking energy out of the zero-point radiation field.