MARXISM AND QUANTUM MECHANICS 35 from J M Jauch at the Varenna Conference of 1970: ... It is a most remarkable fact, with no parallel in the history of science, that although quantum mechanics has become the indispensable basic theory for all of microphysics and for much of macrophy-sics as well, its interpretation has remained a source of conflict from its inception in the late twenties until today. The epistemological questions associated with the so-called Copenhagen interpretation are so profound and revolutionary that many of the founders of this theory (among them Einstein, De Broglie and Schrodinger) have rejected this interpretation and for many thoughtful physicists of a more practical bend of mind it has remained a kind of 'skeleton in the closet' . . . Such familiar concepts as the physical system, causality and determinism, are all put in question or have acquired a new meaning . . . Most of all,, as has been particularly emphasized by Einstein it is the notion of'objective reality'of the physical world, the cornerstone of all classical physics, which has become practically obliterated in the new physics. Although it is not clear what exactly is meant by ^physi-cal reality9 it is conceivable that the underlying idea of this term could be made precise by physics. The analysis of Einstein, Podo-Isky and Rosen together with Bohr's reply has made it clear that quantum mechanics is precisely not capable of doing that and according to one's point of view one may find comfort or a source of concern in that situation.2 This crisis which is a reflection of the general crisis in science "arises from the fact that the very discoveries of science, the deepening of knowledge of the laws of motion of matter, have proved incompatible with the metaphysical ways of thinking and mechanist categories which were the armoury of science at an earlier stage of its development.??R It is the aim of this essay to explain in non-technical language the nature of the basic contradictions of quantum theory, to show how they arise from. the mechanistic world outlook and to demonstrate how the dialectical materialist approach points a way out of the present situation. II Waves and particles signify two different ways of transporting energy from one point to another: a floating piece of cork can be made to move either by throwing stones at it or by producing waves in the water which will travel to the cork. Since waves and particles have historically represented a basic dualism in physics let us consider some of their properties. Typical properties of particles arc mass, position, velocity, momentum (mass into velocity) and energy. For waves we have frequency (number of oscillations a second), wave length (distance from one crest to the next) amplitude and speed of propagation. For a fixed speed of propagation if we increase the frequency the wave length becomes less. If we produce