The atoms of spacetime and the cosmological constant

@article{Padmanabhan2017TheAO,
  title={The atoms of spacetime and the cosmological constant},
  author={Thanu Padmanabhan},
  journal={Journal of Physics: Conference Series},
  year={2017},
  volume={880}
}
  • T. Padmanabhan
  • Published 20 February 2017
  • Physics
  • Journal of Physics: Conference Series
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… 
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References

SHOWING 1-10 OF 36 REFERENCES

The Atoms Of Space, Gravity and the Cosmological Constant

I describe an approach which connects classical gravity with the quantum microstructure of spacetime. The field equations arise from maximizing the density of states of matter plus geometry. The…

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.

Entropy density of spacetime from the zero point length

Exploring the Nature of Gravity

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…

General relativity from a thermodynamic perspective

I show that the gravitational dynamics in a bulk region of space can be connected to a thermodynamic description in the boundary of that region, thereby providing clear physical interpretations of…

Cosmic information, the cosmological constant and the amplitude of primordial perturbations

Entropy density of spacetime as a relic from quantum gravity

There is a considerable amount of evidence to suggest that the field equations of gravity have the same status as, say, the equations describing an emergent phenomenon like elasticity. In fact, it is…

Cosmological Constant from the Emergent Gravity Perspective

Observations indicate that our universe is characterized by a late-time accelerating phase, possibly driven by a cosmological constant $\Lambda$, with the dimensionless parameter $\Lambda L_P^2…

Thermodynamic structure of the Einstein tensor

We analyze the generic structure of Einstein tensor projected onto a 2D spacelike surface S defined by a unit timelike and spacelike vectors u and n, respectively, which describe an accelerated…

Action principle for the fluid-gravity correspondence and emergent gravity

It has been known for a long time that Einstein’s field equations when projected onto a black hole horizon look very similar to a Navier-Stokes equation in suitable variables. More recently, it was…