Useful Links
Physics
General Relativity
Mathematical Formulation
Tensor Calculus
Introduction to Tensors
Definition and basic properties
Differences from vectors and scalars
Types of tensors: covariant, contravariant, mixed
Tensor algebra: addition, multiplication, contraction
Metric Tensor
Role in describing spacetime
Relationship with distance and angles in curved space
Metric signature and its implications for general relativity
Examples of common metrics: Minkowski, Schwarzschild
Riemann Curvature Tensor
Definition and interpretation
Relation to the notion of curvature in differential geometry
Calculation via the Christoffel symbols
Properties and symmetries, such as Bianchi identities
Role in determining manifold curvature
Ricci Curvature Tensor
Definition as a contraction of the Riemann tensor
Role in Einstein's Field Equations
Geometrical significance in the context of volume change
Einstein Tensor
Definition and relation to the Ricci tensor
Conservation law connections
Importance in forming the left side of Einstein's Field Equations
Einstein's Field Equations
Origin and derivation from the Einstein-Hilbert action
Explanation of the equation and its components
Physical interpretation: relationship between matter and spacetime curvature
The cosmological constant and its implications for cosmology
Linearized field equations and weak-field approximations
Equations of Motion
Geodesic Equation
Derivation using the principle of extremal aging
Role in defining freely falling paths in a gravitational field
Effects of spacetime curvature on the motion of particles
Solutions to the Field Equations
Schwarzschild Solution
Characteristics of the Schwarzschild metric
Application to non-rotating, spherically symmetric masses
Implications for black holes and event horizons
Connection with Birkhoff’s theorem
Kerr Solution
Description of rotating black holes
Introduction to the Kerr metric and its properties
Effects of angular momentum on spacetime: frame dragging
Reissner-Nordström Solution
Extension of Schwarzschild solution to include charge
Characteristics of charged black holes
Role in theoretical studies of charged black hole stability
Friedmann-Lemaître-Robertson-Walker (FLRW) Metrics
Application in cosmological models of the universe
Description of homogeneous and isotropic universes
Derivation and significance of the Friedmann equations
Role in big-bang cosmology and cosmological constant discussions
1. Overview of General Relativity
First Page
3. Key Concepts