Quantum gravity remains one of the most significant problems in modern theoretical physics. To the extent that a putative quantum theory requires harmonizing the formal lessons of general relativity and quantum field theory - both of which carry a heavy structural and conceptual baggage - the search for a quantum theory of gravity is an extraordinarily fertile and dense playground. There are in fact a myriad of different proposals in tackling the problem - from the Fierz-Pauli action of the early days of the field to the more modern descriptions of string theory and loop quantum gravity - each with different mathematical structures and points of emphasis.
The purpose of this talk is to pedagogically introduce the spin-foam approach to quantum gravity - a non-perturbative and background-independent quantization of the metric field with ties to loop quantum gravity. With the goal of being pedagogical, the talk is divided into two sessions: a first session on purely classical general relativity (more suitable to a general audience), where I intend to revisit GR in a gauge formulation and discuss some less well-known nuances of the theory so as to set the stage; and a second session on spin-foams proper, where I shall work towards presenting a simple toy model and - if time permits - its correspondence to the classical theory.
Outline Session 1
17th of October: Room F42, Department of Physics, University of Coimbra
Revisiting General RelativityQuantum gravity remains one of the most significant problems in modern theoretical physics. To the extent that a putative quantum theory requires harmonizing the formal lessons of general relativity and quantum field theory - both of which carry a heavy structural and conceptual baggage - the search for a quantum theory of gravity is an extraordinarily fertile and dense playground. There are in fact a myriad of different proposals in tackling the problem - from the Fierz-Pauli action of the early days of the field to the more modern descriptions of string theory and loop quantum gravity - each with different mathematical structures and points of emphasis.
The purpose of this talk is to pedagogically introduce the spin-foam approach to quantum gravity - a non-perturbative and background-independent quantization of the metric field with ties to loop quantum gravity. With the goal of being pedagogical, the talk is divided into two sessions: a first session on purely classical general relativity (more suitable to a general audience), where I intend to revisit GR in a gauge formulation and discuss some less well-known nuances of the theory so as to set the stage; and a second session on spin-foams proper, where I shall work towards presenting a simple toy
1 - Foundational principles and first-order gauge formulation
2 - Measurements and invariance
3 - Expectations for a quantum theory
[Ideal prerequisites: general relativity and basic differential geometry]
Session 2 - Introduction to Spin-foams
18th of October: Room D10A, Department of Physics, University of Coimbra
1 - Quantizing the sphere
2 - Quantizing a polyhedron
3 - Getting our feet wet: a spin-foam for 3d Riemannian gravity
4 - The semiclassical limit
5 - Open-ended discussion on the field
[Ideal prerequisites: notions of QFT and representation theory of SU(2)]
Organized by: Catarina Cosme