Since its inception, the intricate mathematical formalism of quantum mechanics has empowered physicists to describe and predict specific physical events known as quantum processes. However, this success in probabilistic predictions has been accompanied by a profound challenge in the ontological interpretation of the theory. This interpretative complexity stems from two key aspects. Firstly, quantum mechanics is a fundamental theory that, so far, is not derivable from any more basic scientific theory. Secondly, it delves into a realm of invisible phenomena that (...) often contradicts our intuitive and commonsensical notions of matter and causality. Despite its notorious difficulties of interpretation, the most widely accepted set of views of quantum phenomena has been known as the Copenhagen interpretation since the beginning of quantum mechanics. According to these views, the correct ontological interpretation of quantum mechanics is incompatible with ontological realism in general and with philosophical materialism in particular. Anti-realist and anti-materialist interpretations of quantum matter have survived until today. This paper discusses these perspectives, arguing that materialistic interpretations of quantum mechanics are compatible with its mathematical formalism, while anti-realist and anti-materialist views are based on wrong philosophical assumptions. However, although physicalism provides a better explanation for quantum phenomena than idealism, its downward reductionism prevents it from accounting for more complex forms of matter, such as biological or sociocultural systems. Thus, the paper argues that neither physicalism nor idealism can explain the universe. I propose then a non-reductionistic form of materialism called inclusive materialism. The conclusion is that the acknowledgment of the qualitative irreducibility of ontological emergent levels above the purely physical one does not deny philosophical materialism but enriches it. (shrink)

We analyze the interrelation of quantum and classical entanglement. The latter notion is widely used in classical optic simulation of some quantum-like features of light. We criticize the common interpretation that “quantum nonlocality” is the basic factor differing quantum and classical realizations of entanglement. Instead, we point to the breakthrough Grangier et al. experiment on coincidence detection which was done in 1986 and played the crucial role in rejection of classical field models in favor of quantum mechanics. Classical entanglement sources (...) produce light beams with the coefficient of second order coherence \} \ge 1.\) This feature of classical entanglement is obscured by using intensities of signals in different channels, instead of counting clicks of photo-detectors. The interplay between intensity and clicks counting is not just a technicality. We elevate this issue to the high foundational level. (shrink)