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Gravity Informed


Chatwin-Davies, Aidan Émile (2018) Gravity Informed. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ZD4W-4C63.


Formulating a universally satisfactory theory of quantum gravity is a long-standing open problem in theoretical physics. Relatively recently, the use of techniques from quantum information has emerged as a powerful tool for analyzing phenomena that lie at the intersection of quantum theory and gravitation. This thesis describes several advances and novel proposals that were made regarding information theoretic aspects of quantum gravity in three broad areas: holography, cosmology, and the black hole information problem.

Regarding holography, we first assess the differences between typical holographic states and fully random states. Next, we show that determining Ryu-Takayanagi surfaces in AdS3/CFT2 is computationally easy from a complexity-theoretic standpoint. Finally, we identify precise consistency conditions that constrain the validity of an early tensor network model for the AdS/CFT correspondence that uses the Multiscale Entanglement Renormalization Ansatz (MERA).

Regarding cosmology, we propose an alternative interpretation of the MERA as a discretization of de Sitter spacetime. Next, we return to holographic ideas and show that an appropriately-defined Generalized Second Law implies a cosmic no-hair theorem for certain classes of cosmological spacetimes. Finally, we advance an information-theoretic proposal for calculating the signature of a quantum gravity-motivated, fully covariant, natural ultraviolet cutoff in the spectrum of inflationary perturbations.

Regarding the black hole information problem, we begin by exhibiting a simple protocol which, under highly specific circumstances, allows one to retrieve a single qubit from a black hole. Next, we propose an operational resolution of the black hole information problem in which observers who enter the black hole could never detect an inconsistency between their experiences and quantum mechanics due to the finite amount of time available before reaching the central singularity. Finally, we discuss a proposal to understand the emergence of an ensemble of definite geometries during the process of black hole evaporation as a decoherence process, as well as its implications for the black hole information problem.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Quantum Gravity; Quantum Information; Holography; Cosmology; Black Holes
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Carroll, Sean M.
Group:Walter Burke Institute for Theoretical Physics
Thesis Committee:
  • Cheung, Clifford W. (chair)
  • Preskill, John P.
  • Weinstein, Alan Jay
  • Carroll, Sean M.
Defense Date:17 May 2018
Funding AgencyGrant Number
Gordon and Betty Moore Foundation776
Caltech Department of PhysicsBeatrice and Sai-Wai Fu Fellowship
Record Number:CaltechTHESIS:05282018-130631568
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Ch. 2 adapted for Ch. 3 adapted for Ch. 4 adapted for Ch. 5 adapted for Ch. 6 adapted for Ch. 7 adapted for Ch. 9 adapted for Ch. 10 adapted for Ch. 11
Chatwin-Davies, Aidan Émile0000-0003-1406-9271
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10954
Deposited By: Aidan Chatwin Davies
Deposited On:29 May 2018 21:46
Last Modified:26 Oct 2021 17:49

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