# General relativity as the equation of state of spin foam

@article{Smolin2012GeneralRA, title={General relativity as the equation of state of spin foam}, author={Lee Smolin}, journal={Classical and Quantum Gravity}, year={2012}, volume={31} }

Building on recent significant results of Frodden, Ghosh and Perez (FGP) and Bianchi, I present a quantum version of Jacobsonʼs argument that the Einstein equations emerge as the equation of state of a quantum gravitational system. I give three criteria a quantum theory of gravity must satisfy if it is to allow Jacobsonʼs argument to be run. I then show that the results of FGP and Bianchi provide evidence that loop quantum gravity satisfies two of these criteria, and argue that the third should…

## 26 Citations

### Spacetime thermodynamics without hidden degrees of freedom

- Physics
- 2014

A celebrated result by Jacobson is the derivation of Einstein's equations from Unruh's temperature, the Bekenstein-Hawking entropy and the Clausius relation. This has been repeatedly taken as…

### Black holes in loop quantum gravity

- PhysicsReports on progress in physics. Physical Society
- 2017

This is a review of results on black hole physics in the context of loop quantum gravity, finding the discreteness of geometric quantities at the Planck scale predicted by this approach to quantum gravity to be key.

### The scaling of black hole entropy in loop quantum gravity

- Physics
- 2012

We discuss some general properties of black hole entropy in loop quantum gravity from the perspective of local stationary observers at distance l from the horizon. The present status of the theory…

### Twistorial structure of loop-gravity transition amplitudes

- Physics
- 2012

The spin foam formalism provides transition amplitudes for loop quantum gravity. Important aspects of the dynamics are understood, but many open questions are pressing on. In this paper we address…

### Thermodynamics of Quantum Isolated Horizons with model Hamiltonians

- Physics
- 2013

Following a recent proposal, we consider the most general structure possible for the Hamiltonian operator associated with the Quantum Isolated Horizon(QIH) with explanations of the underlying…

### Atoms of Spacetime and the Nature of Gravity

- PhysicsEntropy
- 2015

This principle implies that: (1) the metric cannot be varied in any extremum principle to obtain the field equations; and (2) the stress-tensor of matter should appear in the variational principle through the combination of $T_{ab}n^an^b$ where $n_a$ is an auxiliary null vector field, which could be varied to get the field equation.

### A Topological Extension of General Relativity to Explore the Nature of Quantum Space-time, Dark Energy and Inflation

- Physics
- 2013

General Relativity is extended into the quantum domain. A thought experiment is explored to derive a specific topological build-up for Planckian spacetime. The presented arguments are inspired by…

### O ct 2 01 2 The scaling of black hole entropy in loop quantum gravity

- Physics
- 2013

We discuss some general properties of black hole entropy in loop quantum gravity from the perspective of local stationary observers at distance l from the horizon. The present status of the theory…

### Dynamical evaporation of quantum horizons

- Physics
- 2013

We describe the black hole evaporation process driven by the dynamical evolution of the quantum gravitational degrees of freedom resident at the horizon, as identified by the loop quantum gravity…

### Temporal Relationalism

- Physics, PhilosophyBeyond Spacetime
- 2020

Because of the non-locality of quantum entanglement, realist approaches to completing quantum mechanics have implications for our conception of space. Quantum gravity also is expected to predict…

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