Technically, the only thing that is known not to exist is local hidden variables. There are non-local hidden variable theories which are consistent with all kno

Technically, the only thing that is known not to exist is local hidden variables. There are non-local hidden variable theories which are consistent with all known experiments. Unfortunately, they are also not distinguishable by experiment from more mainstream interpretations of QM. Here is an example of a non-local hidden variable theory: http://en.wikipedia.org/wiki/Bohm_interpretation http://en.wikipedia.org/wiki/Bohm_interpretation