Master Presentation: Maja Bartczak
When:Fr 17-07-2026 10.00 a.m. - 11.00 a.m.Where:Feringa Building 5612.0153
Master Presentation: Maja Bartczak
When:
17 July 2026, 10:00
Where:
Feringa Building 5612.0153
Title:
Perturbative quantum gravity
Abstract:
The quantization of gravity remains one of the central open problems in
modern theoretical physics. Although General Relativity provides a highly
successful classical description of gravitation, its geometric formulation fundamentally
differs from the quantum field theories that describe the other
fundamental interactions. A useful approach to this problem is to study gravity
in the weak-field regime, where the spacetime metric may be treated as a
small perturbation about flat Minkowski spacetime and interpreted as a massless
spin-2 field. This thesis investigates the covariant quantization of the free
massless spin–2 field associated with linearized gravity. Beginning from the
weak-field expansion of the Einstein–Hilbert action, the linearized Einstein
equations are derived and the gauge structure of the theory is analysed. The
physical particle content of the theory is then established through the representation
theory of the Poincaré group, demonstrating that a massless spin–2
field possesses only two physical helicity states. The equivalence between the
weak-field limit of General Relativity and the Fierz–Pauli theory is also discussed.
The quantum theory is developed using Gupta’s covariant quantization
procedure. The Gupta–Bleuler formalism for the electromagnetic field is
first reviewed as a prototype example of quantization in the presence of gauge
redundancy. The method is then generalized to the spin–2 field, leading
to the construction of the covariant Hilbert space, the identification of
negative-norm states, and the imposition of a subsidiary condition that isolates
the physical graviton states while preserving Lorentz covariance.
Finally, the path-integral quantization of linearized gravity
is developed through gauge fixing and the Faddeev–Popov procedure. The
perturbative non-renormalizability of quantum gravity is discussed, together
with its interpretation as an effective field theory. As an application, tree-level
scattering amplitudes and post-Minkowskian gravitational potentials are examined,
illustrating how quantum field theoretic methods reproduce classical
gravitational interactions. The resulting framework provides a mathematically
consistent and conceptually transparent treatment of the free graviton field
and offers an instructive setting in which many of the fundamental challenges
of quantum gravity can already be studied.