A Background Independent Algebra in Quantum Gravity

Understand

We propose an algebra of operators along an observer's worldline as a background-independent algebra in quantum gravity.

• In that context, it is natural to think of the Hartle-Hawking no boundary state as a universal state of maximum entropy, and to define entropy in terms of the relative entropy with this state.
• In the case that the only spacetimes considered correspond to de Sitter vacua with different values of the cosmological constant, this definition leads to sensible results.