On page 3 of this new paper of Gerard 't Hooft it is written: This paper was written while these facts were being discovered, so that it represents an original train of thought, which may actually be useful for the reader. Here is a paper that contemplates a deterministic basis for Quantum Mechanics and aspires to help "demystify" quantum mechanics. http://arxiv.org/abs/quant-ph/0604008 The mathematical basis for deterministic quantum mechanics Gerard 't Hooft 15 pages, 3 figures ITP-UU-06/14, SPIN-06/12 Here is a quote from the conclusions: When we attempt to regard quantum mechanics as a deterministic system, we have to face the problem of the positivity of the Hamiltonian, as was concluded earlier in Refs . There, also, the suspicion was raised that information loss is essential for the resolution of this problem. In this paper, the mathematical procedures have been worked out further, and we note that the deterministic models that we seek must have short limit cycles, obeying Eq. (7.1). Short limit cycles can easily be obtained in cellular automaton models with information loss, but the problem is to establish the addition rule (7.4), which suggests the large equivalence classes defined by Eq. (4.2). We think that the observations made in this paper are an important step towards the demystification of quantum mechanics. Here is the abstract: "If there exists a classical, i.e. deterministic theory underlying quantum mechanics, an explanation must be found of the fact that the Hamiltonian, which is defined to be the operator that generates evolution in time, is bounded from below. The mechanism that can produce exactly such a constraint is identified in this paper. It is the fact that not all classical data are registered in the quantum description. Large sets of values of these data are assumed to be indistinguishable, forming equivalence classes. It is argued that this should be attributed to information loss, such as what one might suspect to happen during the formation and annihilation of virtual black holes. The nature of the equivalence classes is further elucidated, as it follows from the positivity of the Hamiltonian. Our world is assumed to consist of a very large number of subsystems that may be regarded as approximately independent, or weakly interacting with one another. As long as two (or more) sectors of our world are treated as being independent, they all must be demanded to be restricted to positive energy states only. What follows from these considerations is a unique definition of energy in the quantum system in terms of the periodicity of the limit cycles of the deterministic model."