A recent concept in theoretical physics, motivated in string duality and M–theory, is the notion that not all quantum theories arise from quantising a classical system. Also, a given quantum model may possess more than just one classical limit. In view of these developments, we analyse some general properties that quantum mechanics must satisfy, if it is not to be formulated as a quantisation o...

This letter briefly gives an overview of the theory proposed in quant-ph/9906130 and quant-ph/9909025 on the basis of quantum mechanics. Although quantum mechanics in twentieth century has succeeded to predict the correct results of large numbers of experiments in the process to find new fundamental particles in the nature, it seems to have left some fundamental open problems, both structural a...

An investigation is made into how the foundations of statistical mechanics are affected once we treat classical mechanics as an approximation to quantum mechanics in certain domains rather than as a theory in its own right; this is necessary if we are to understand statistical-mechanical systems in our own world. Relevant structural and dynamical differences are identified between classical and...