Constructing Reality: Quantum Theory and Particle Physics

C. S. Unnikrishnan

This chapter examines the nature of physical reality in the context of unavoidable unobservables in physics. One of the features of science, especially physical science, is a powerful urge to construct theories of phenomena, instead of just cataloging and classifying phenomena and their spatio-temporal patterns. The concept of fields' of various kinds dominates physical theory and modern physics, and fields are essential to both classical and quantum theories. The concept of physical reality in the context of the Einstein, Podolsky and Rosen (EPR) assertion of the incompleteness of quantum mechanics is perhaps appropriate. Quantum theory of physical systems consisting of large number of particles led to the concept of a quantum field associated with the particles, a generalisation of the wave function itself. Space and time are supreme and primary unobservables in physics, without any reality independent of matter, notwithstanding their modern status as the dynamical arena of gravitational effects as described in Einstein's general theory of relativity.

David Hodgson

Cao Tianyu

In this essay,I argue that the basic entities in the causality organized hierarchy of entities that quantum field theory describes are not particles but fields.Then I move on to discuss,from the perspective of a structural realist,in what sense and to what degree this theoretical construction of fields can be taken as an objective representation of physical reality.

Robert B. Griffiths

Mani Lal Bhaumik

Albert Einstein is considered by many physicists as the father of quantum physics in some sense. Yet there is an unshakable view that he was wrong on quantum physics. Although it may be a subject of considerable debate, the core of his allegedly wrong demurral was the insistence on finding an objective reality underlying the manifestly bizarre behavior of quantum objects. The uncanny wave-particle duality of a quantum particle is a prime example. In view of the latest developments, particularly in quantum field theory, the objections of Einstein are substantially corroborated. Careful investigation suggests that a travelling quantum particle is a holistic wave packet consisting of an assemblage of irregular disturbances in quantum fields. It acts as a particle because only the totality of all the disturbances in the wave packet yields the energy-momentum with the mass of a particle, along with its other conserved quantities such as charge and spin. Thus the wave function representing a particle is not just a fictitious mathematical construct but embodies a reality of nature as asserted by Einstein. Quanta 2015; 4: 35–42.

Bunge, Mario