# Thermodynamics of quantum spacetime histories

@article{Smolin2015ThermodynamicsOQ, title={Thermodynamics of quantum spacetime histories}, author={Lee Smolin}, journal={Physical Review D}, year={2015}, volume={96}, pages={104042} }

We show that the simplicity constraints, which define the dynamics of spin foam models, imply, and are implied by, the first law of thermodynamics, when the latter is applied to causal diamonds in the quantum spacetime. This result reveals an intimate connection between the holographic nature of gravity, as reflected by the Bekenstein entropy, and the fact that general relativity and other gravitational theories can be understood as constrained topological field theories. To state and derive…

## 10 Citations

### Atoms of Spacetime and the Nature of Gravity

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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.

### Exploring the Nature of Gravity

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I clarify the differences between various approaches in the literature which attempt to link gravity and thermodynamics. I then describe a new perspective based on the following features: (1) As in…

### Temporal Relationalism

- Physics, PhilosophyBeyond Spacetime
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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…

### Optical and thermodynamic properties of a rotating dyonic black hole spacetime in N = 2 , U ( 1 ) 2 gauged supergravity

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The null geodesics and the distance of closest approach for photon around a rotating dyonic black hole in N = 2 , U ( 1 ) 2 gauged supergravity is studied. The phenomenon of black hole shadows with…

### Optical and thermodynamic properties of a rotating dyonic black hole spacetime in $${\mathcal {N}} = 2, U(1)^2$$ gauged supergravity

- Physics
- 2021

The null geodesics and the distance of closest approach for photon around a rotating dyonic black hole in N = 2, U(1) gauged supergravity is studied. The phenomenon of black hole shadows with various…

### The KBC void and Hubble tension contradict ΛCDM on a Gpc scale − Milgromian dynamics as a possible solution

- PhysicsMonthly Notices of the Royal Astronomical Society
- 2020

The KBC void is a local underdensity with the observed relative density contrast δ ≡ 1 − ρ/ρ0 = 0.46 ± 0.06 between 40 and 300 Mpc around the Local Group. If mass is conserved in the Universe, such…

### The Star Formation History and Dynamics of the Ultra-diffuse Galaxy Dragonfly 44 in MOND and MOG

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The observed line-of-sight velocity dispersion σlos of the ultra-diffuse galaxy Dragonfly 44 (DF44) requires a Newtonian dynamical mass-to-light ratio of solar units. This is well outside the…

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Some reflections are presented on the state of the search for a quantum theory of gravity. I discuss diverse regimes of possible quantum gravitational phenomenon, some well explored, some novel.

### Holographic relations in loop quantum gravity

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- 2016

It is shown that a relation between entropy and minimal area holds in loop quantum gravity, reminiscent of the Ryu-Takayanagi relation.

### Applied Scientific Demiurgy I – Entrance Examination Information Sheet

- EducationJournal of Humanistic Mathematics
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This document provides all the required information needed by aspiring demiurges to sit the entrance examination for the foundation course Applied Scientific Demiurgy I in the scientific stream of…

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