Conceptual Issues, Foundational Questions and Quantum Cosmology

Claus Kiefer

Babak Ghaffarzadagan

This paper introduces Reconstructive Metaphysics as a conceptual and interpretive framework addressing foundational questions in quantum mechanics and cosmological multiverse theories. Rather than proposing a new physical theory, it offers a meta-interpretive approach that reframes quantum indeterminacy, cosmological plurality, time, and consciousness as expressions of a single, dynamically reconstructing reality. The work is intended for researchers in physics, philosophy of science, cosmology, and interdisciplinary studies.

Eduard Prugovečki

J. J. Halliwell

The development of quantum cosmology, in which Stephen Hawking played a crucial role, has frequently encountered substantial conceptual and technical difficulties related to the problem of time in quantum gravity and to general issues concerning the foundations of quantum theory. In this contribution to Stephen's 60th Birthday Conference, I describe some recent work in which the decoherent histories approach to quantum theory is used to quantize simple cosmological models and perhaps shed some light on some of these difficulties.

Don Nelson Page

Huang Pengjie

This work presents a conceptual and representational framework aimed at clarifying the structural relationships among established physical theories across relativistic, quantum, and cosmological regimes. Rather than proposing new dynamical laws, particles, or experimentally testable predictions, the manuscript focuses on how existing physical descriptions may be consistently interpreted within a unified representational structure. The proposed Dual-Spacetime Projection Framework distinguishes between an underlying descriptive domain and an observed effective spacetime, connected through a scale-dependent projection. This distinction is intended as a formal and interpretative tool, not as an ontological claim about the existence of multiple physical spacetimes. Within this perspective, several foundational features of modern physics—such as Lorentz invariance, finite signal propagation, quantum uncertainty, and large-scale cosmological behavior—are discussed as consequences of representational structure rather than as independent postulates. The manuscript is positioned as a contribution to the foundations of theoretical physics, offering a coherent conceptual lens for organizing and interpreting existing theories. It is intended for readers interested in foundational questions, conceptual unification, and the representational aspects of physical law, and does not rely on experimental data or numerical simulation.