Discussion Overview
The discussion revolves around the quantization of the gravitational field in a weak field regime, specifically focusing on the Hamiltonian formulation of the theory of free particles, referred to as gravitons. Participants explore the relationship between the Hamiltonian of this theory and that of the free electromagnetic field, as well as the relevant literature for further study.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- One participant asserts that it is possible to quantize the gravitational field in a weak field regime, leading to a theory of free particles known as gravitons, similar to the electromagnetic field.
- Another participant suggests several references, including Donoghue's lecture notes and DeWitt's work, while cautioning that older references may not align with the effective field theory perspective.
- A participant questions whether the Hamiltonian operator for the gravitational theory is the same as that for the free electromagnetic field.
- It is noted that the field operator in linearized gravity has spin 2, indicating that the Hamiltonians cannot be the same, and a suggestion is made to start with the Lagrangian to derive the Hamiltonian through a Legendre transformation.
- One participant proposes that the Hamiltonian for the weak gravitational field should resemble that of the free Klein-Gordon field, acknowledging potential differences in constants but emphasizing a desire for a formal expression.
- Another participant suggests using the Wheeler-DeWitt equation and linearization, or starting with the linearized Lagrangian while applying gauge constraints.
Areas of Agreement / Disagreement
Participants express differing views on the relationship between the Hamiltonians of the gravitational and electromagnetic fields, with no consensus reached on whether they are the same or different. The discussion remains unresolved regarding the exact form of the Hamiltonian in this context.
Contextual Notes
Participants highlight the importance of understanding the Lagrangian for covariant quantum field theory and the potential need for gauge conditions, indicating that the discussion may depend on specific assumptions and definitions related to the theory.