Theoretical physicist specializing in high-energy theory, string theory, quantum gravity, statistical physics, etc.
Quantum Field Theory (QFT) Overview
Objective: Develop concepts for momentum analytics for quantum dynamics of fields.
Classical dynamics (e.g., Maxwell's equations) describe electric and magnetic fields classically. However, quantum mechanics provides a different picture.
Quantum Electrodynamics (QED): Leads to the concept of photons as mediators of electromagnetic interactions.
Quantum field theory offers new physical insights different from classical theory.
Importance of Quantum Field Theory
Fundamental Interactions: Three out of four fundamental interactions in nature are described by QFT.
Quantum Gravity: While not complete, QFT techniques help understand certain quantum gravity questions.
Applications: Over the years, QFT methods have become important in other areas like condensed matter and statistical physics.
Universal Language: Essential for theoretical physics across various fields. Important for both theorists and experimentalists.
Course Structure
Course Goal: To appreciate and understand quantum electrodynamics.
Sequence: First in a series of master-level courses. This semester focuses on fundamental concepts; subsequent courses will delve into technical development.
Outline: Provided on the course website; serves as a rough roadmap subject to change.
Difficulty: QFT is often seen as difficult mainly due to conceptual challenges rather than the complexity of calculations.
Learning Approach: Emphasizes developing intuition through multiple examples.
Instructions for Students
Philosophy: Fundamental understanding and formalism should be tied to solving concrete physical problems.
Examples and Problems: Essential for developing intuition and reinforcing learning. Important to reflect on problems after solving them.
Learning Outside Class: Most learning will happen outside the classroom through problem sets (Psets) and examples.
Rotations: Notations in lectures might differ from textbooks (Peskin and Weinberg). Students need to adapt between different conventions.
Concepts and Principles
Principle of Locality
Action at a Distance: Classical Newtonian mechanics involves action at a distance (e.g., gravity, Coulomb interactions).
Locality: Principle stating that physical points in space participate in the physical process, as formulated by Faraday.
Fields as Mathematical Devices: Fields are tools to realize the principle of locality.
Field Examples: Scalar fields, vector fields (electric and magnetic fields), tensor fields, and spinor fields.
Formalism
Action Principle for Classical Fields: Derived from the principle of locality.
Field Lagrangian: Must only involve single integrals over space-time and should depend on value and first derivatives of fields.
Canonical Momentum and Hamiltonian: Can be defined for field theories similar to particle mechanics.