Regular Article - Theoretical Physics
Running of effective dimension and cosmological entropy in early universe
Key Laboratory of High-precision Computation and Application of Quantum Field Theory of Hebei Province, College of Physical Science and Technology, Hebei University, 071002, Baoding, China
2 Department of Physics and Astronomy, University of Sussex, BN1 9QH, Brighton, UK
Accepted: 6 December 2020
Published online: 14 December 2020
In this paper, we suggest that the early universe starts from a high-energetic state with a two dimensional description and the state recovers to be four dimensional when the universe evolves into the radiation dominated phase. This scenario is consistent with the recent viewpoint that quantum gravity should be effectively two dimensional in the ultraviolet and recovers to be four dimensional in the infrared. A relationship has been established between the running of effective dimension and that of the entropy inside particle horizon of the universe, i.e., as the effective dimension runs from two to four, the corresponding entropy runs from the holographic entropy to the normal entropy appropriate to radiation. These results can be generalized to higher dimensional cases.
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