58 SOCIAL SCIENTIST in terms of underlying processes such as the action of a postulated 'pilot wave'. However, de Broglie's theory met with strong criticism. The most important criticism, which was levelled by Pauli, was that in a two-body scattering process, the model could not be applied coherently. As a result of this strong attack de Broglie abandoned his suggestion. The whole lot of leading scientists plumped for the Bohr-Heisenberg line, which later on came to be known as the Copenhagen Interpretation of Quantum Mechanics(CIQM). The CIQM has an excellent formalism which leads to results that agree with experiment with great accuracy and covers an extremely wide range of phenomena. As yet there are no experimental indications of any domain in which this theory might break down. In spite of this, as the authors maintain, "... there still remain a number of basic questions concerning its fundamental significance which are obscure and confused. Thus, for example, one of the leading physicists of our time M. Gell-Mann describes "Quantum Mechanics, (as) that mysterious confusing discipline, which none of us really understands but which we know how to use." Just what points are not clear in the conventional theory have been specified in detail throughout the book. However, a few of them have been outlined separately which we give below. 1) Though the quantum theory treats statistical ensembles in a satisfactory way and predicts the behaviour of collections of particles, e.g. electrons and neutrons, we are unable in this theory to describe individual quantum processes without bringing in unsatisfactory assumptions, such as regarding the collapse of the wave function. 2) There is the well known problem of nonlocality which has been brought out by J.S. Bell in connection with the paradox of Einstein, Podolsky-Rosen (EPR experiment). 3) There is the mysterious 'wave-particle duality' in the properties of matter which is demonstrated in a quantum interference experiment. 4) Above all, there is the inability to give a clear notion of what the reality of quantum system could be. Bohm and Hiley explain how it is necessary to move from an epistemo-logical to an ontological theory of quantum mechanics. Regarding the CIQM they make the following criticism: "All that is clear about the quantum theory is that it contains an algorithm for computing the probabilities of experimental results. But it gives no physical account of individual quantum processes. Indeed, without the measuring instruments in which the predicted results appear, the equations of quantum theory would be just pure mathematics that would have no physical meaning at all. And thus quantum theory merely gives us (generally statistical) knowledge of how our instruments will function. And from this we can make inferences that will contribute to our knowledge, for example, of how to carry out various technical processes. That is to say, it seems as indeed Bohr and Heisenberg have implied, that quantum theory is concerned