  The non-classical features of quantum mechanics are reproduced using models
constructed with a classical theory - general relativity. The inability to
define complete initial data consistently and independently of future
measurements, non-locality, and the non-Boolean logical structure are
reproduced by these examples. The key feature of the models is the role of
topology change. It is the breakdown of causal structure associated with
topology change that leads to the apparently non-classical behaviour. For
geons, topology change is required to describe the interaction of particles. It
is therefore natural to regard topology change as an essential part of the
measurement process. This leads to models in which the measurement imposes
additional non-redundant boundary conditions. The initial state cannot be
described independently of the measurement and there is a causal connection
between the measurement and the initial state.
