General relativity as the equation of state of spin foam

  title={General relativity as the equation of state of spin foam},
  author={Lee Smolin},
  journal={Classical and Quantum Gravity},
  • L. Smolin
  • Published 24 May 2012
  • Physics
  • Classical and Quantum Gravity
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… 

Spacetime thermodynamics without hidden degrees of freedom

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

  • A. Perez
  • Physics
    Reports 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

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

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

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

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

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

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

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

  • L. Smolin
  • Physics, Philosophy
    Beyond 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



Thermodynamics of spacetime: The Einstein equation of state.

  • Jacobson
  • Physics
    Physical review letters
  • 1995
The Einstein equation is derived from the form of black hole entropy together with the fundamental relation $\delta Q=TdS$ connecting heat, entropy, and temperature, and its validity is seen to depend on the existence of local equilibrium conditions.

Path integral representation of spin foam models of 4D gravity

We give a unified description of all recent spin foam models introduced by Engle, Livine, Pereira and Rovelli (ELPR) and by Freidel and Krasnov (FK). We show that the FK models are, for all values of

Linking topological quantum field theory and nonperturbative quantum gravity

Quantum gravity is studied nonperturbatively in the case in which space has a boundary with finite area. A natural set of boundary conditions is studied in the Euclidean signature theory in which the

Comments on "On the Origin of Gravity and the Laws of Newton", by Erik Verlinde

We argue that the relativistic Unruh temperature cannot be associated with the bits on the screen, in the form considered by Verlinde. The acceleration $a$ is a scalar quantity (the modulus of the

Zakopane lectures on loop gravity

This is a first version of the introductory lectures on loop quantum gravity that I will give at the quantum gravity school in Zakopane. The theory is presented in self-contained form, without

On the semiclassical limit of 4d spin foam models

We study the semiclassical properties of the Riemannian spin foam models with Immirzi parameter that are constructed via coherent states. We show that, in the semiclassical limit, the quantum spin

Entropy of Non-Extremal Black Holes from Loop Gravity

We compute the entropy of non-extremal black holes using the quantum dynamics of Loop Gravity. The horizon entropy is finite, scales linearly with the area A, and reproduces the Bekenstein-Hawking

A local first law for black hole thermodynamics

We first show that stationary black holes satisfy an extremely simple local form of the first law \delta E=\kappa(l) \delta A/(8 \pi) where the thermodynamical energy E=A/(8\pi l) and (local) surface

UvA-DARE ( Digital Academic Repository ) On the origin of gravity and the laws of

Starting from first principles and general assumptions we present a heuristic argument that shows that Newton’s law of gravitation naturally arises in a theory in which space emerges through a

Entropy of static spacetimes and microscopic density of states

A general ansatz for gravitational entropy can be provided using the criterion that any patch of area which acts as a horizon for a suitably defined accelerated observer must have an entropy