Next Article in Journal
Estimating a Repeatable Statistical Law by Requiring Its Stability During Observation
Next Article in Special Issue
Entropy and Quantum Gravity
Previous Article in Journal
Extension of the Improved Bounce-Back Scheme for Electrokinetic Flow in the Lattice Boltzmann Method
Previous Article in Special Issue
Thermal BEC Black Holes
Article Menu

Export Article

Open AccessReview
Entropy 2015, 17(11), 7420-7452; doi:10.3390/e17117420

Distribution Function of the Atoms of Spacetime and the Nature of Gravity

IUCAA, Pune University Campus, Ganeshkhind, Pune 411007, India
Academic Editor: Raúl Alcaraz Martínez
Received: 3 September 2015 / Revised: 16 October 2015 / Accepted: 20 October 2015 / Published: 28 October 2015
(This article belongs to the Special Issue Entropy in Quantum Gravity and Quantum Cosmology)
View Full-Text   |   Download PDF [343 KB, uploaded 28 October 2015]

Abstract

The fact that the equations of motion for matter remain invariant when a constant is added to the Lagrangian suggests postulating that the field equations of gravity should also respect this symmetry. 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 Tabnanb where na is an auxiliary null vector field, which could be varied to get the field equations. This procedure uniquely selects the Lanczos–Lovelock models of gravity in D-dimensions and Einstein’s theory in D = 4. Identifying na with the normals to the null surfaces in the spacetime in the macroscopic limit leads to a thermodynamic interpretation for gravity. Several geometrical variables and the equation describing the spacetime evolution acquire a thermodynamic interpretation. Extending these ideas one level deeper, we can obtain this variational principle from a distribution function for the “atoms of spacetime”, which counts the number of microscopic degrees of freedom of the geometry. This is based on the curious fact that the renormalized spacetime endows each event with zero volume, but finite area! View Full-Text
Keywords: spacetime entropy; emergent gravity; cosmological constant; horizon entropy; quantum gravity; zero-point length; horizon thermodynamics spacetime entropy; emergent gravity; cosmological constant; horizon entropy; quantum gravity; zero-point length; horizon thermodynamics
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Padmanabhan, T. Distribution Function of the Atoms of Spacetime and the Nature of Gravity. Entropy 2015, 17, 7420-7452.

Show more citation formats Show less citations formats

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Entropy EISSN 1099-4300 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top