Some problems of quantum cosmology and dark matter physics
Wang, Jin
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/20571
Description
Title
Some problems of quantum cosmology and dark matter physics
Author(s)
Wang, Jin
Issue Date
1991
Doctoral Committee Chair(s)
Nanopoulos, Dimitri
Department of Study
Astronomy
Discipline
Astronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Astronomy and Astrophysics
Language
eng
Abstract
In this thesis we study the quantum cosmology of the string universe obtained by embedding the Robertson-Walker metric in the non-linear $\sigma$ model. We find that initially the universe exists in a series of metastable bound states with the scale factor taking discrete values. Then it tunnels through a barrier and comes out in an inflationary state. This tunneling (or evolution in imaginary time) also has the effect of heating up the matter field so that we have a condition of chaotic inflation. Our asymptotic solutions agree with those obtained from the classical Einstein equations.
We consider quantum cosmology of a 4 dimensional universe using the effective action of superstrings. We apply both Hartle-Hawking and Vilenkin boundary conditions to the solution of Wheeler-DeWitt equation. We find that under certain conditions (fermions added) the universe will tunnel through to the Lorentzian regime from the Euclidean regime and time is dynamically generated.
We apply Chudnovsky and Vilenkin's idea of possible existence of cosmic strings in the Sun. Stellar evolution with cosmic strings at solar age gives us a radius and luminosity of the star which are in contradiction with observation.
We study the astrophysical bound on the change of gravitational constant with time. We find that $\vert\dot G/G\vert < 10\sp{-12}yr\sp{-1}$ is the condition that has to be satisfied in order not to cause the conflict with observation.
We study the effect of axions on the steller evolution of a 10 solar mass star model. If the axion mass is larger than.1 ev the star's age is significantly different at late stages, compared to the star without axions.
We argue that if cosmions (or WIMPS) solve the solar neutrino problem, then they must also play an important role in the evolution of low mass star main sequence stars; If they do so, then a simple (long mean free path) model for the interaction of cosmions with baryons leads to changes in the structure of the nuclear-burning core which may in principle be observable.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
