  Some of the so-called imponderables and counterintuitive puzzles associated
with the Copenhagen interpretation of quantum mechanics appear to have
alternate, parallel explanations in terms of nonlinear dynamics and chaos.
These include the mocking up of exponetial decay in closed systems, possible
nonlinear extensions of Bell's inequalities, spontaneous symmetry breaking and
the existence of intrinsically preferred internal oscillation modes
(quantization) in nonlinear systems, and perhaps even the production of
diffraction-like patterns by "order in chaos." The existence of such parallel
explanations leads to an empirical, quasi-experimental approach to the question
of whether or not there might be fundamental nonlinearities underying quantum
mechanics. This will be contrasted with recent more theoretical approaches, in
which nonlinear extensions have been proposed rather as corrections to a
fundamentally linear quantum mechanics. Sources of nonlinearity, such as
special relativity and the measurement process itself, will be investigated, as
will possible implications of nonlinearities for entanglement and decoherence.
It is conceivable that in their debates both Einstein and Bohr could have been
right -- for chaos provides the fundamental determinism favored by Einstein,
yet for practical measurements it requires the probabilistic interpretation of
the Bohr school.
