2:22

Ashtekar variables, which were a new canonical formalism of general relativity, raised new hopes for the canonical quantization of general relativity and eventually led to loop quantum gravity. Smolin and others independently discovered that there exists in fact a Lagrangian formulation of the theory by considering the self-dual formulation of the Tetradic Palatini action principle of general relativity. These proofs were given in terms of spinors. A purely tensorial proof of the new variables in terms of triads was given by Goldberg and in terms of tetrads by Henneaux et al. Here we in particular fill in details of the proof of results for self-dual variables not given in text books.

### The Palatini action

### Self-dual variables

### Derivation of main results for self-dual variables

### Derivation of Ashtekar's Formalism from the Self-dual Action