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Constraints on Cosmology and Quantum Gravity from Quantum Mechanics and Quantum Field Theory

Citation

Pollack, Jason Aaron (2017) Constraints on Cosmology and Quantum Gravity from Quantum Mechanics and Quantum Field Theory. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9W093ZG. http://resolver.caltech.edu/CaltechTHESIS:05252017-171005406

Abstract

Typical cosmological states have structure, obey to very good approximation the laws of classical physics on large scales, and are far from equilibrium. Typical quantum-mechanical states have none of these properties. If the universe is described by a state in a Hilbert space, the state and its Hilbert space must therefore obey a number of constraints to describe realistic cosmological spacetimes. In particular, they must admit a quantum-to-classical transition via decoherence that allows for the emergence of classical spacetimes, and such spacetimes must obey gravitational constraints, in particular on the entanglement entropy of subsystems within them. The papers collected in this thesis are concerned with these constraints. We investigate two holographic correspondences inspired by AdS/CFT, the AdS-MERA correspondence, which suggests that anti-de~Sitter space may be given a discretized description as a tensor network, and the ER=EPR duality, which identified entangled qubits with wormholes connecting them. In the former case, we use holographic entropy bounds to severely constrain the properties of any such tensor network; in the latter case we prove a new general-relativistic area theorem which states that an area corresponding to the entanglement entropy in wormhole geometries is exactly conserved. We use information-theoretic constraints to show that under mild assumptions about the black hole interior an observer falling beyond the horizon is unable to verify the claimed cloning of information in the firewall paradox before reaching the singularity. Finally, we analyze the decoherence structures of late-time de~Sitter space and early-time slow-roll eternal inflation. We show that in the former case a universe with an infinite-dimensional Hilbert space and a positive cosmological constant inevitably reaches a maximum-entropy state from which no further branching or decoherence is possible, forbidding the existence of dynamical quantum fluctuations at late time. In the latter case, gravitational-strength interaction among inflaton modes leads to decoherence of sufficiently super-Hubble modes, which we argue backreacts to cause different histories of cosmological evolution on different branches and hence creates the conditions necessary for eternal inflation.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Cosmology; quantum gravity
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Awards:Graduate Dean's Award for Outstanding Community Service, 2017.
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Carroll, Sean M.
Group:Walter Burke Institute for Theoretical Physics, Caltech Theory
Thesis Committee:
  • Wise, Mark B. (chair)
  • Carroll, Sean M.
  • Cheung, Clifford W.
  • Weinstein, Alan Jay
Defense Date:19 May 2017
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0011632
Gordon and Betty Moore Foundation776
Record Number:CaltechTHESIS:05252017-171005406
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05252017-171005406
DOI:10.7907/Z9W093ZG
Related URLs:
URLURL TypeDescription
http://arxiv.org/abs/1504.06632arXivarXiv version of article adapted for Ch. 2
http://dx.doi.org/10.1088/0004-637X/804/2/131DOIPublished version of article adapted for Ch. 2
https://arxiv.org/abs/1506.08203arXivarXiv version of article adapted for Ch. 3
http://dx.doi.org/10.1002/prop.201500053DOIPublished version of article adapted for Ch. 3
https://arxiv.org/abs/1509.05426arXivarXiv version of article adapted for Ch. 4
http://dx.doi.org/10.1007/JHEP11(2015)126DOIPublished version of article adapted for Ch. 4
https://arxiv.org/abs/1604.08217arXivarXiv version of article adapted for Ch. 5
http://dx.doi.org/10.1007/JHEP07(2016)048DOIPublished version of article adapted for Ch. 5
https://arxiv.org/abs/1607.05141arXivarXiv version of article adapted for Ch. 6
http://dx.doi.org/10.1007/JHEP12(2016)026DOIPublished version of article adapted for Ch. 6
https://arxiv.org/abs/1405.0298arXivarXiv version of article adapted for Ch. 7
http://dx.doi.org/10.1007/s10701-016-9996-8 DOIPublished version of article adapted for Ch. 7
https://arxiv.org/abs/1612.04894arXivarXiv version of article adapted for Ch. 8
ORCID:
AuthorORCID
Pollack, Jason Aaron0000-0003-4754-4905
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10209
Collection:CaltechTHESIS
Deposited By: Jason Pollack
Deposited On:30 May 2017 23:26
Last Modified:12 Dec 2018 22:44

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