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Gravity and is Thermodynamics


Affiliations
1 Inter-University Centre for Astronomy and Astrophysics, Pune University Campus, Ganeshkhind, Pune 411 007, India
 

The equations of motion describing all physical systems, excluding gravity, remain invariant if a constant is added to the Lagrangian. In the conventional approach, gravitational theories break this symmetry exhibited by all other physical systems. Restoring this symmetry to gravity and demanding that gravitational field equations should also remain invariant under the addition of a constant to a Lagrangian, leads to the interpretation of gravity as the thermodynamic limit of the kinetic theory of atoms of space. This approach selects, in a very natural fashion, Einstein's general relativity in d = 4. Developing this paradigm at a deeper level, one can obtain the distribution function for the atoms of space and connect it up with the thermodynamic description of spacetime. This extension relies on a curious fact that the quantum spacetime endows each event with a finite area but zero volume. This approach allows us determine the numerical value of the cosmological constant and suggests a new perspective on cosmology.

Keywords

Emergent Gravity, Horizon Thermodynamics, Quantum Gravity, Spacetime Entropy.
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  • Gravity and is Thermodynamics

Abstract Views: 379  |  PDF Views: 130

Authors

T. Padmanabhan
Inter-University Centre for Astronomy and Astrophysics, Pune University Campus, Ganeshkhind, Pune 411 007, India

Abstract


The equations of motion describing all physical systems, excluding gravity, remain invariant if a constant is added to the Lagrangian. In the conventional approach, gravitational theories break this symmetry exhibited by all other physical systems. Restoring this symmetry to gravity and demanding that gravitational field equations should also remain invariant under the addition of a constant to a Lagrangian, leads to the interpretation of gravity as the thermodynamic limit of the kinetic theory of atoms of space. This approach selects, in a very natural fashion, Einstein's general relativity in d = 4. Developing this paradigm at a deeper level, one can obtain the distribution function for the atoms of space and connect it up with the thermodynamic description of spacetime. This extension relies on a curious fact that the quantum spacetime endows each event with a finite area but zero volume. This approach allows us determine the numerical value of the cosmological constant and suggests a new perspective on cosmology.

Keywords


Emergent Gravity, Horizon Thermodynamics, Quantum Gravity, Spacetime Entropy.

References





DOI: https://doi.org/10.18520/cs%2Fv109%2Fi12%2F2236-2242