The atoms of spacetime and the cosmological constant

Abstract

I describe an approach which relates classical gravity to the quantum microstructure of spacetime. In this approach, the field equations arise from maximizing the density of states of the matter plus geometry. The former is identified using the thermodynamics of null surfaces. The latter arises from the existence of a zero-point length in the spacetime which associates an internal degree of freedom with each event in the spacetime, in the form of a fluctuating vector of constant norm. The density of states, as well as the resulting gravitational field equations, remain invariant when a constant is added to the matter Lagrangian, which is a symmetry of the matter sector. The cosmological constant arises as an integration constant and renders the amount of cosmic information accessible to an eternal observer finite. The relation between the cosmological constant and the cosmic information allows us to determine the numerical value of cosmological constant from the information content of the quantum spacetime, within the context of cosmology.

Updated version of the plenary talk given at DICE2016 on `Spacetime - Matter - Quantum Mechanics', September 12-16, 2016, Castiglioncello (Italy); to appear in the proceedings; 1 figure; 19 pages

References in corpus (7)

• Entropy density of spacetime and the Navier-Stokes fluid dynamics of null surfaces
• Noether current from the surface term of gravitational action, Virasoro algebra and horizon entropy
• Grin of the Cheshire cat: Entropy density of spacetime as a relic from quantum gravity
• Vacuum Fluctuations and the Small Scale Structure of Spacetime
• Cosmological Constant from the Emergent Gravity Perspective
• The thermodynamic structure of Einstein tensor
• Cosmic Information, the Cosmological Constant and the Amplitude of primordial perturbations

Cited by in corpus (12)

• Quantum metric for null separated events and spacetime atoms
• Emergence of space and expansion of universe
• Euclidean Action and the Einstein tensor
• Minimum-length Ricci scalar for null separated events
• Information content and minimum-length metric: A drop of light
• Modified Measures as an Effective Theory for Causal Fermion Systems
• The cosmological constant of emergent spacetime in the Newtonian approximation
• Zero-point gravitational field equations
• Evolution of Universe as a Homogeneous System : Changes of Scale Factors with Different Dark Energy EoS-s
• The Kinetic Theory of the Mesoscopic Spacetime
• A Measure for Quantum Paths, Gravity and Spacetime Microstructure
• Hyperbolic space in the Newtonian limit: the cosmological constant