Discussion Overview
The discussion revolves around the concept of boundaries in spinfoams and spin networks within Loop Quantum Gravity (LQG) theory. Participants explore definitions, relationships between bulk and boundary, and the significance of these boundaries in the context of LQG.
Discussion Character
- Exploratory
- Technical explanation
- Conceptual clarification
Main Points Raised
- One participant questions whether the boundary of a spinfoam is indeed a spin network and seeks definitions for boundaries in both spinfoams and spin networks.
- Another participant suggests consulting a specific book that discusses classical discretization of General Relativity and the connection between bulk and boundary, particularly in the context of 3D and 4D spacetime.
- A third participant references a research paper that defines the notion of a boundary and discusses the spin network basis for the boundary Hilbert space.
- One participant proposes that in a spin network, a boundary consists of a minimal set of edges that connect two vertices, provided there is no alternative path that avoids these edges.
- There are technical issues noted regarding the accessibility of the book's draft version, with participants discussing the functionality of the provided link.
Areas of Agreement / Disagreement
Participants express varying interpretations of what constitutes a boundary in spinfoams and spin networks, indicating that multiple competing views remain. The discussion does not reach a consensus on definitions or the nature of boundaries.
Contextual Notes
Some definitions and assumptions regarding boundaries in spinfoams and spin networks remain unresolved, and there are references to specific sections in literature that may clarify these concepts further.